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A Combination of Green Tea Extract and L-Theanine Improves Memory and Attention in Subjects with Mild Cognitive Impairment: A Double-Blind Placebo-Controlled Study

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Abstract

A combination of green tea extract and l-theanine (LGNC-07) has been reported to have beneficial effects on cognition in animal studies. In this randomized, double-blind, placebo-controlled study, the effect of LGNC-07 on memory and attention in subjects with mild cognitive impairment (MCI) was investigated. Ninety-one MCI subjects whose Mini Mental State Examination-K (MMSE-K) scores were between 21 and 26 and who were in either stage 2 or 3 on the Global Deterioration Scale were enrolled in this study. The treatment group (13 men, 32 women; 57.58 ± 9.45 years) took 1,680 mg of LGNC-07, and the placebo group (12 men, 34 women; 56.28 ± 9.92 years) received an equivalent amount of maltodextrin and lactose for 16 weeks. Neuropsychological tests (Rey-Kim memory test and Stroop color-word test) and electroencephalography were conducted to evaluate the effect of LGNC-07 on memory and attention. Further analyses were stratified by baseline severity to evaluate treatment response on the degree of impairment (MMSE-K 21-23 and 24-26). LGNC-07 led to improvements in memory by marginally increasing delayed recognition in the Rey-Kim memory test (P = .0572). Stratified analyses showed that LGNC-07 improved memory and selective attention by significantly increasing the Rey-Kim memory quotient and word reading in the subjects with MMSE-K scores of 21-23 (LGNC-07, n = 11; placebo, n = 9). Electroencephalograms were recorded in 24 randomly selected subjects hourly for 3 hours in eye-open, eye-closed, and reading states after a single dose of LGNC-07 (LGNC-07, n = 12; placebo, n = 12). Brain theta waves, an indicator of cognitive alertness, were increased significantly in the temporal, frontal, parietal, and occipital areas after 3 hours in the eye-open and reading states. Therefore, this study suggests that LGNC-07 has potential as an intervention for cognitive improvement.

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... Three experimental studies (Borgwardt et al., 2012;Park et al., 2011;Schmidt et al., 2014) investigated the effects of green tea or green tea extract: two the acute effects in healthy participants, one the chronic effects in patients with mild cognitive impairment (Park et al., 2011). ...
... Three experimental studies (Borgwardt et al., 2012;Park et al., 2011;Schmidt et al., 2014) investigated the effects of green tea or green tea extract: two the acute effects in healthy participants, one the chronic effects in patients with mild cognitive impairment (Park et al., 2011). ...
... Thus, no cognitive benefit was demonstrated, as this study only measured brain activation. Park et al. (2011) showed that combined administration of GTE and L-theanine was beneficial to a more affected subgroup (Mini Mental State Examination (MMSE) 21-23) of their sample of participants suffering from mild cognitive impairment (MMSE 21-26), in that it increased verbal and visuospatial memory and attention. Twenty-three (23) random EEGs, equally divided between intervention and control, showed that this treatment significantly enhanced theta waves during the states "eyes open" and "reading" (but not in "eyes closed" ). ...
Article
Background: Green tea (Camellia sinensis) is a beverage consumed for thousands of years. Numerous claims about the benefits of its consumption were stated and investigated. As green tea is experiencing a surge in popularity in Western culture and as millions of people all over the world drink it every day, it is relevant to understand its effects on the human brain. Purpose: To assess the current state of knowledge in the literature regarding the effects of green tea or green tea extracts, l-theanine and epigallocatechin gallate both components of green tea-on general neuropsychology, on the sub-category cognition and on brain functions in humans. Methods: We systematically searched on PubMed database and selected studies by predefined eligibility criteria. We then assessed their quality and extracted data. We structured our effort according to the PRISMA statement. Outcome: We reviewed and assessed 21 studies, 4 of which were randomised controlled trials, 12 cross-over studies (both assessed with an adapted version of the DELPHI-list), 4 were cross-sectional studies and one was a cohort study (both assessed with an adapted version of the Newcastle-Ottawa assessment scale). The average study quality as appraised by means of the DELPHI-list was good (8.06/9); the studies evaluated with the Newcastle-Ottawa-scale were also good (6.7/9). Conclusions: The reviewed studies presented evidence that green tea influences psychopathological symptoms (e.g. reduction of anxiety), cognition (e.g. benefits in memory and attention) and brain function (e.g. activation of working memory seen in functional MRI). The effects of green tea cannot be attributed to a single constituent of the beverage. This is exemplified in the finding that beneficial green tea effects on cognition are observed under the combined influence of both caffeine and l-theanine, whereas separate administration of either substance was found to have a lesser impact.
... Gomez-Ramirez et al. (2007) reported that an increase of task-related α-activity and a decrease of background-related α-brainwave activity result in an improvement of selective attention [116]. Moreover, the enhancement of cognitive performance was explained by the increase in monoamines, by the neuroprotective effects of glutamate [12] and by the increase of brain theta waves [118]. However, it should be noted that the majority of studies measures brain activity rather than behavioral effects such as attention, reaction time, and alertness [5]. ...
... Effects on cognitive performance, in particular on attention, memory, and information processing have been found at much lower doses between 60 mg and 250 mg [116,118,172]. All of the studies, which found significant effects on mood or psychological well-being, in particular subjective stress, anxiety, and relaxation, applied doses ranging from 200 mg to 400 mg [119,121,173]. ...
... Furthermore, it was suggested that L-theanine might only selectively influence certain brain regions [172]. Park et al. (2011) treated participants with mild cognitive impairment (Mini Mental State Examination (MMSE) score 21 -26) with 360 mg green tea extract in combination with 60 mg Ltheanine. L-theanine increased theta activity during active mental states suggesting that L-theanine beneficially influences cognitive function such as memory and attention. ...
Article
Background: Green tea is traditionally known to induce mental clarity, cognitive function, physical activation and relaxation. Recently, a special green tea, matcha tea, is rapidly gaining popularity throughout the world and is frequently referred to as a mood- and brain food. Matcha tea consumption leads to much higher intake of green tea phytochemicals compared to regular green tea. Previous research on tea constituents caffeine, L-theanine, and epigallocatechin gallate (EGCG) repeatedly demonstrated benefits on mood and cognitive performance. These effects were observed when these phytochemicals were consumed separately and in combination. Methods: A review was conducted on 49 human intervention studies to summarize the research on acute psychoactive effects of caffeine, L-theanine, and EGCG on different dimensions of mood and cognitive performance. Conclusions: Caffeine was found to mainly improve performance on demanding long-duration cognitive tasks and self-reported alertness, arousal, and vigor. Significant effects already occurred at low doses of 40 mg. L-theanine alone improved self-reported relaxation, tension, and calmness starting at 200 mg. L-theanine and caffeine combined were found to particularly improve performance in attention-switching tasks and alertness, but to a lesser extent than caffeine alone. No conclusive evidence relating to effects induced by EGCG could be given since the amount of intervention studies was limited. These studies provided reliable evidence showing that L-theanine and caffeine have clear beneficial effects on sustained attention, memory, and suppression of distraction. Moreover, L-theanine was found to lead to relaxation by reducing caffeine induced arousal.
... Несколько исследований [47][48][49] были посвящены изу чению влияния теанина в сочетании с катехинами зеленого чая на пациентов с когнитивными расстройствами. Во всех случаях наблюдалось улучшение когнитивных показателей, в том числе памяти и внимания. ...
... Для всех этих заболеваний также характерно снижение уровня BDNF [63]. Способность теанина подавлять эксайтотоксичность глутамата, дофаминовую нейротоксичность и активировать антиоксидантную систему клеток служит дополнительным теоретическим обоснованием для его возможного применения при этих заболеваниях, тем более что имеется позитивный клинический опыт применения теанина при когнитивных расстройствах [47][48][49]. ...
Article
Theanine is an analog of glutamate and the major aminoacid in green tea. It has received growing attention in recent years because of its beneficial effects on the central nervous system. Theanine was shown to increase levels of brain-derived neurotrophic factor and to stimulate neurogenesis. Anti-stress and calming effects of theanine are the most apparent and well-studied. A number of studies showed neuroprotective effects of theanine after an ischemic cerebral injury or the exposure to toxic chemicals. It also improved cognitive function including attention, memory and learning. Recent studies demonstrated a promising role of theanine in augmentation therapy for major depressive disorder and schizophrenia. Theoretical grounds for using theanine in treatment of bipolar disorder, anxiety disorder and some neurodegenerative disorders are discussed.
... Tea is understood to have overall health benefits, including that of reduced cognitive decline and improved MCI (Ng et al., 2008;Park et al., 2011). Green tea is found to be associated with lower rates of cognitive impairment (Kuriyama et al., 2006;Ng et al., 2008), and black fermented and semifermented tea (oolong) have both been shown to significantly reduce cognitive decline in old age (Ng et al., 2008). ...
... Green tea is found to be associated with lower rates of cognitive impairment (Kuriyama et al., 2006;Ng et al., 2008), and black fermented and semifermented tea (oolong) have both been shown to significantly reduce cognitive decline in old age (Ng et al., 2008). This is possibly due to naturally occurring chemical compounds such as theanine in both black and green tea (Ng et al., 2008;Park et al., 2011). Natural compounds found in various types of tea reduce acetylcholinesterase activity and protect β-amyloid driven affects on cognition (Ng et al., 2008). ...
Article
There are many factors that strongly influence the aetiology, development, and progression of cognitive decline in old age, mild cognitive impairment (MCI), and Alzheimer’s disease (AD). These factors include not only different personality traits and moods but also lifestyle patterns (e.g. exercise and diet) and awareness levels that lead to cognitive decline in old age. In this review, we discuss how personality traits, mood states, and lifestyle impact brain and behaviour in older adults. Specifically, our review shows that these lifestyle and personality factors affect several brain regions, including the hippocampus, a region key for memory that is affected by cognitive decline in old age as well as AD. Accordingly, appropriate recommendations are presented in this review to assist individuals in decreasing chances of MCI, dementia, AD, and associated symptoms.
... The results of human studies investigating the effects of green tea on cognition have been mixed, but there are indications of promise [52][53][54]. Some epidemiological studies have detected a negative correlation between consumption and cognitive dysfunction [55], while others have failed to find any association [56]. ...
... This finding was replicated more recently in a study that found increased EEG activity 1 h after green tea consumption [58]. A long-term intervention study found that consumption of a mixture of green tea extract and the amino acid l-theanine for 16 weeks was associated with increased theta wave EEG activity and improved memory and selective attention in participants with MCI [53]. In a small acute-intervention clinical study, green tea intake was dose-dependently associated with increased activation of the dorsolateral prefrontal cortex as measured by fMRI [59]. ...
Article
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Purpose of review: Evidence suggests that flavonoids, polyphenolic compounds found in many plant-derived foods, such as berries, may allay cognitive impairment. We review recent research exploring the protective effects of flavonoids on age-related cognitive decline and neurodegenerative disorders in humans and animals. We also address the mechanisms by which flavonoids may exert their effects and promising avenues of future research. Recent findings: Flavonoids have been found to decrease neuroinflammation, reduce oxidative stress, and mediate neuroplasticity in animal models of neurodegeneration and aging. Injecting flavonoids encased in metal nanoparticles may further enhance the efficacy of flavonoids. Animal studies also demonstrate that flavonoid supplementation may alleviate neurodegenerative cognitive and memory impairments. Limited human studies, however, demonstrate the need for further clinical research investigating flavonoids. Flavonoid supplementation, as well as dietary modification to include whole foods high in flavonoids, may provide therapeutic potential for aging individuals experiencing cognitive deficits resulting from neurodegeneration.
... All the other parameters, including PCV and blood cells, total protein, and albumin, remain unchanged except for little change ( Figure 5). The Prednisolone administration in healthy doges with different dosage changes in blood pressure, body weight, adrenal gland size, and blood serum (Park et al., 2011). The dose rate 2 mg/kg/d for 2 wk, 1 mg/kg/d for 4 wk and 0.4 mg/kg/d in 3 wk. ...
... The change was mild but not significantly different from baseline values. They show some minimal effect with a low dosage of prednisolone (Park et al., 2011). The study indicates that some steroids modulate the temperature of the body. ...
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Hematology and serum biochemistry study may provide antique knowledge about the physical status of individuals, making them a valuable tool to differentiate healthy animals from affected animals. We aimed to investigate Steroid safety levels in birds through ex-situ studies at regular therapeutic doses. A total of 100 birds were used for hematology and serum biochemistry. This study was designed into two trials over the summer and winter, each comprised five, ten, fifteen, and twenty days. Each study group was based on five control group birds and 20 experimental group birds. A sum of two groups representing two different Steroids trial groups was treated with therapeutic doses t the stretch of five, ten, fifteen, and twenty days each season. A therapeutic dose of each of the Steroids was given at the rate of three drops two times a day to each bird. Analysis of data reveals that Steroids had severe effects on bird's (Coturnix coturnix) hematological parameters. In most trials, the hematological effects of Bromocriptine as mesylate showed an increase in Red blood cell count and White blood cell count. On the other hand, steroid Estradiol Valerate showed a decrease in these parameters. Effect of steroids on serum biochemistry profile indicate acute damage to vital organs, especially to liver and kidney, indicating an increase in cholesterol, total protein, albumin, urea, and uric acid. The overall effect of steroids on the bird's serum and biochemistry of quails were nearly similar but different only in their intensity.
... All the other parameters, including PCV and blood cells, total protein, and albumin, remain unchanged except for little change ( Figure 5). The Prednisolone administration in healthy doges with different dosage changes in blood pressure, body weight, adrenal gland size, and blood serum (Park et al., 2011). The dose rate 2 mg/kg/d for 2 wk, 1 mg/kg/d for 4 wk and 0.4 mg/kg/d in 3 wk. ...
... The change was mild but not significantly different from baseline values. They show some minimal effect with a low dosage of prednisolone (Park et al., 2011). The study indicates that some steroids modulate the temperature of the body. ...
Article
Full-text available
Hematology and serum biochemistry study may provide antique knowledge about the physical status of individuals, making them a valuable tool to differentiate healthy animals from affected animals. We aimed to investigate Steroid safety levels in birds through ex-situ studies at regular therapeutic doses. A total of 100 birds were used for hematology and serum biochemistry. This study was designed into two trials over the summer and winter, each comprised five, ten, fifteen, and twenty days. Each study group was based on five control group birds and 20 experimental group birds. A sum of two groups representing two different Steroids trial groups was treated with therapeutic doses t the stretch of five, ten, fifteen, and twenty days each season. A therapeutic dose of each of the Steroids was given at the rate of three drops two times a day to each bird. Analysis of data reveals that Steroids had severe effects on bird's (Coturnix coturnix) hematological parameters. In most trials, the hematological effects of Bromocriptine as mesylate showed an increase in Red blood cell count and White blood cell count. On the other hand, steroid Estradiol Valerate showed a decrease in these parameters. Effect of steroids on serum biochemistry profile indicate acute damage to vital organs, especially to liver and kidney, indicating an increase in cholesterol, total protein, albumin, urea, and uric acid. The overall effect of steroids on the bird's serum and biochemistry of quails were nearly similar but different only in their intensity.
... Green tea extract has been reported to reduce neuroblastoma cell death induced by amyloid β [206]. LGNC-07, which is a combination of green tea extract and L-theanine, is noticed to improve memory and learning in cognition impairment human model, tested by electroencephalography and neuropsychological tests [207]. Increase in theta brain waves upon green tea consumption were observed, which is an indicator of increased brain activity [208]. ...
Article
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Green tea (Camellia sinensis) is a famous herb, and its extract has been extensively used in traditional Chinese medicinal system. In this context, several studies have revealed its health benefits and medicinal potentialities for several ailments. With ever increasing scientific knowledge, search for safer, potential and novel type of health-related supplements quest, scientists are re-directing their research interests to explore natural resources i.e. medicinal herbs/plant derived compounds. Green tea consumption has gained a special attention and popularity in the modern era of changing lifestyle. The present review is aimed to extend the current knowledge by highlighting the importance and beneficial applications of green tea in humans for safeguarding various health issues. Herein, we have extensively reviewed, analyzed, and compiled salient information on green tea from the authentic published literature available in PubMed and other scientific databases. Scientific literature evidenced that owing to the bioactive constituents including caffeine, L-theanine, polyphenols/ flavonoids and other potent molecules, green tea has many pharmacological and physiological functions. It possesses multi-beneficial applications in treating various disorders of humans. This review also provides in-depth insights on the medicinal values of green tea which will be useful for researchers, medical professionals, veterinarians, nutritionists, pharmacists and pharmaceutical industry. Future research emphasis and promotional avenues are needed to explore its potential therapeutic applications for designing appropriate pharmaceuticals, complementary medicines, and effective drugs as well as popularize and propagate its multidimensional health benefits.
... Green tea extract has been studied for its effects on metabolism (minor fat reducing effect) and cognition. Of note, a meta-analysis on the effects of green tea on body weight concluded that consuming green tea will not increase weight loss [51]. When studying its effect on cognition, a double-blind placebo study done on 45 subjects with mild cognitive impairment showed some beneficial effect [52]. ...
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The current demanding and busy lifestyle has spawned the development of supplements that are marketed as energy and concentration boosters. Energy shots are one of the most popular such supplements due to their small volume and efficient packaging. The components of energy shots have very limited evidence supporting their effects, and their efficacy is not consistently proven. This literature review from the past 40 years utilized PubMed, MEDLINE, SCOPUS and EMBASE, using the following keywords: ‘energy beverage’, ‘energy drink’, ‘energy shot’, ‘power shot’, ‘power energy’, ‘exercise’, ‘caffeine’, ‘glucose’, ‘ginseng’, ‘guarana’, ‘l-tyrosine’, ‘green tea extract’, ‘quercetin’, ‘garcinia cambogia extract’, ‘yerba mate’, and ‘taurine’. The effects of each ingredient individually, as well as of energy shots in general, were summarized, and recommendations on use and safety of energy shots are provided.
... These neuroprotective effects are generally attributed mainly to its antioxidant capacity but may also be related to its anti-inflammatory action, PKC activation, inhibition of acetylcholinesterase, and effects on other pathways (Ide and Yamada, 2015). Furthermore, epidemiological research shows that daily consumption of green tea provides benefits for cognitive function (Ide et al., 2014;Park et al., 2011;Wightman et al., 2012). Our data show that green tea consumption, for a short period, could prevent deficits into short-and long-term recognition memory in rats submitted to two different types of stroke, consistent with the idea that the compounds in green tea produced beneficial changes in cognitive function. ...
Article
This study investigate the effect of green tea (GT) on short and long term declarative memory and oxidative damage induced by transient ischemia-reperfusion (IR) and intracerebral hemorrhage (ICH) in rats. Male Wistar rats were divided into 8 groups of 10 according the stroke type induced were used: Sham IR, Sham IR + GT, IR, IR + GT, Sham ICH, Sham ICH + GT, ICH, ICH + GT. Supplementation with GT was initiated 10 days before stroke surgery and continuous for 6 days after (GT dose 400 mg/kg). Short (STM) and long term memory (LTM) we evaluated with object recognition task (OR) and hippocampus were used to evaluate parameters related to oxidative stress (ROS, lipid peroxidation and total antioxidant capacity). The rats subjected to IR and ICH showed STM and LTM deficits and GT intervention prevents it in both stroke models. IR and ICH induced increase on ROS levels in hippocampus. ICH increased the lipid peroxidation in hippocampus and the GT supplementation avoids it. IR induced decrease on total antioxidant capacity and GT prevent it. These results reveal that GT supplementation presented a neuroprotective role, attenuates redox imbalance and might be a beneficial impact on cognitive function after stroke.
... In addition, neuropsychological evaluations confirmed the beneficial effects of the supplement in cognitive impairment. The tolerability of this natural remedy was confirmed and no sign of adverse effect was observed in this study (Park et al., 2011). ...
Article
Over the past decade, a wide range of scientific investigations have been performed to reveal neuropathological aspects of cognitive disorders; however, only limited therapeutic approaches currently exist. The failures of conventional therapeutic options as well as the predicted dramatic rise in the prevalence of cognitive decline in the coming future show the necessity for novel therapeutic agents. Recently, a wide range of research has focused on pharmacological activities of green tea catechins worldwide. Current investigations have clarified mechanistic effects of the catechins in inflammatory cascades, oxidative damages, different cellular transcription as well as transduction pathway in various body systems. It has been demonstrated that green tea polyphenols prevent age‐related neurodegeneration through improvement of endogenous antioxidant defense mechanisms, modulation of neural growth factors, attenuation of neuroinflammatory pathway, and regulation of apoptosis. The catechins exhibited beneficial effects in cellular and animal models of neurodegenerative diseases including Alzheimer’s disease, MS, and Parkinson’s disease. The present review discusses the current pharmacological targets, which can be involved in the treatment of cognitive decline and addresses the action of catechin derivatives elicited from green tea on the multiple neural targets.
... Park et al. reported on the effects of the supplement (LGNC-07), which included 1440 mg/day green tea extract [81]. Ninety-one individuals with mild cognitive impairment (MCI) participated in the study and took the supplement for 16 weeks. ...
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Alzheimer’s disease (AD) is one of the most common neurodegenerative disorders worldwide. Its incidence is gradually increasing because of an aging demographic. Therefore, AD prevention and modification is important to improve the health status of older adults. Oxidative stress is a component of the pathological mechanisms underlying AD. It is caused by a disruption of the balance between reactive oxygen species and antioxidant molecules. This imbalance also causes neuroinflammation. Catechins, which are bioactive components of tea, have antioxidative and anti-inflammatory effects. Moreover, other potential properties related to AD prevention and modification have been reported in in vitro and in vivo studies. Several clinical studies have also been conducted to date. The current review summarizes recent updates and perspectives of the effects of catechins on AD based on the molecular mechanisms and related clinical studies.
... Amongst the treatments used in trying to manage MCI and/or delay progression to dementia are: acetylcholinesterase -inhibitors (rivastigmine, galantamine, donepezil), antioxidants (Vitamine E, selegiline, Ginko Biloba), dopamine receptor agonists (piribedil), sex steroid hormones (testosterone injections for men and conjugated equine oestrogen for women), antiinflamatory agents (refecoxib) (12), peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists (rosiglitazone and pioglitazone) (13), vitamin B complex (folic acid, cyanocobalamin and pyridoxine) (14), acetyl-L-carnitine (15), intranasal insulin (16), transdermal nicotine (17), melatonin (18), fluoxetine (19), combination of green tea extract and l-theanine (20), Yamabushitake mushroom (21)thought to have compounds which enhance nerve growth factor synthesis and acupuncture (22). Of the ones mentioned, only fluoxetine showed some promising results as discussed below. ...
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Mild cognitive impairment, also considered a "pre-dementia" stage, has a prevalence of 10-20% in people aged 65 or more. The risk increases with age and is higher in the male gender. Nearly 10% to 15% of MCI patients progress to a diagnosis of probable AD each year, relative to only 1% to 2% of the general elderly population. The importance of successfully treatment of this early illness phases cannot be overstated. At the moment there is no solid pharmacological evidence of a drug that can improve symptoms of mild cognitive impairment or delay its progress to dementia. The current treatment options include: reducing cardiovascular risk factors and prevention of stroke. Social engagement, aerobic exercise, mental activity may help reduce further cognitive decline. In this review we take a closer look at the impact of nonpharmacological treatment on symptom reduction and progression of mild cognitive impairment to dementia.
... In our study, after excluding confounding variables such as age, gender, height, body weight, and BMI, we revealed that caffeine and tea polyphenols in plasma at T 0 and T 1 and in CSF were significantly associated with habitual tea consumption, which was consistent with our common knowledge about patients who had frequent tea consumption. Previous studies have confirmed that caffeine and tea polyphenols play important roles in prevention and intervention for cognitive decline (Ide et al., 2014;Park et al., 2011). Then, how does habitual tea consumption exert impact on neurodegenerative diseases such as POD? ...
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Purpose: To clarify the effects of habitual tea consumption on postoperative delirium (POD) in elderly patients undergoing total hip/knee arthroplasty. Patients and methods: A prospective cohort study was carried out at Qingdao Municipal Hospital Affiliated to Qingdao University between June 2020 and June 2021. A total of 332 patients aged 65-85 years undergoing total hip/knee arthroplasty under combined spinal and epidural anesthesia were enrolled from the Perioperative Neurocognitive Disorder and Biomarker Lifestyle (PNDABLE) study in the final analysis, consisting of 168 patients with habitual tea consumption and 164 patients with infrequent tea consumption. The primary endpoint was the effects of habitual tea consumption on POD and the incidence of POD, which was assessed by the Confusion Assessment Method (CAM) twice daily during the first 7 postoperative days, and POD severity was measured by the Memorial Delirium Assessment Scale (MDAS). The secondary endpoints were the concentrations of caffeine and tea polyphenols in plasma and cerebrospinal fluid (CSF), which were detected by the enzyme-linked immunosorbent assay. Results: POD occurred in 61 of 332 patients (18.37%), among whom 19 had habitual tea consumption (5.72%) and 42 had infrequent tea consumption (12.65%). Habitual tea consumption (odds ratio [OR] = 0.370, 95% confidence interval [CI]: 0.205-0.670, P = .001) was significantly associated with POD in the logistic analysis, and then after adjusting for age and American Society of Anesthesiologists (ASA) physical status (OR = 0.353, 95% CI: 0.190-0.655, P = .001). Furthermore, caffeine in T0 plasma (OR = 0.834, 95% CI: 0.752-0.924, P = .001), T1 plasma (OR = 0.818, 95% CI: 0.738-0.908, P < .001), and CSF (OR = 0.899, 95% CI: 0.820-0.984, P = .022) and tea polyphenols in T0 plasma (OR = 0.541, 95% CI: 0.416-0.704, P < .001), T1 plasma (OR = 0.477, 95% CI: 0.359-0.633, P < .001), and CSF (OR = 0.526, 95% CI: 0.397-0.696, P < .001) were associated with POD after adjusting for age and ASA physical status. Conclusion: Habitual tea consumption may be associated with a lower incidence of POD in elderly patients.
... 23 A randomized, double-blind, placebo-controlled study using a combination of GTE and l-theanine demonstrated improved memory and attention in subjects with mild cognitive impairment. 24 A double-blind, placebo-controlled trial demonstrated that GTE significantly increased visual recognition memory in young adults with Down syndrome. 25 Mechanistically, GTE induction of neuronal plasticity resulted in cognitive improvement. ...
... Two cups of green tea per day was associated with 54% lower risk for cognitive impairment in adults over 70 years old, whereas effects were not evident for black/oolong tea or coffee (7). In subjects with mild cognitive impairment (MCI), consumption of 1.68 g green tea extract daily for four months significantly improved memory and attention (8). ...
Article
Objectives: This study aimed to examine the effects of green tea extract on working memory in healthy younger (21 - 29 y) and older (50 - 63 y) women. Design: A single-blind, placebo-controlled, crossover design was used. Setting: A university laboratory. Participants: Twenty non-smoking Caucasian women were recruited in the younger (10) and older (10) age group. Intervention: Subjects received 5.4 g green tea extract (at least 45% epigallocatechin-3-gallate) or placebo (cornstarch) within a 24-hour period. Measurements: Working memory was measured by reading span and N-back task paradigm. Blood sample (20 mL) was collected and measured for plasma malondialdehyde (MDA) and total antioxidant capacity (TEAC) concentration. A 24-hour recall was conducted for each treatment period to ensure similar dietary patterns. Results: Green tea extract significantly improved reading span performance in older women, indicated by higher absolute and partial scores of reading span. No significant changes were observed in the younger group. N-back latencies and accuracies were not significantly different after green tea treatment in either age group. Plasma concentration of MDA and TEAC were not different after green tea extract in either group. Conclusion: Acute supplementation of decaffeinated green tea extract may enhance working memory capacity of women between 50 to 63 years of age. This study provides preliminary evidence that consumption of green tea extract may enhance the cognitive performance in older adults and thus provide potential chemopreventive benefits in this group. The mechanism should be explored in future research.
... In a rat model of repeated cerebral ischemia, theanine was administered intraperitoneally after the first ischemic insult which reversed the impairment of spatial memory caused by the ischemic event (33). A study evaluated the effect of the combination of green tea and L-Th on patients with mild cognitive impairment and found that the green tea/L-Th combination significantly increased memory and attention of these patients (57). PTSD is a very complex disorder, many rodent PTSD models showed that trauma induced behavioral and memory deficits can occur both immediately and weeks after the traumatic events (58,59). ...
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Post-traumatic stress disorder (PTSD) continues to be one of the most common mental health disorders in the United States and may occur in response to traumatic experiences. Currently, there are no interventions that prevent the development of PTSD. L-Theanine (L-Th), a major compound in green tea has been found to decrease anxiety and prevent memory impairment and may have potential effects in the prevention of PTSD. Sixty rats were divided into six experimental groups: control vehicle, control L-Th, control naïve, PTSD vehicle, PTSD Pre-L-Th (prophylactic), PTSD Post-L-Th (non-prophylactic). PTSD was induced by a 3-day restraint/tail shock stress model. The effects of L-Th on neurobehavior were evaluated by Elevated Plus-Maze (EPM), Morris Water Maze (MWM), and Forced Swim Test (FST). Our study found that the total food intake weight of PTSD Pre-L-Th (prophylactic) rats were significantly increased compared to that of PTSD vehicle rats (p = .04). Administration of L-Th 24 hours before the initial PTSD event or for 10 days following the last PTSD stress event did not statistically improve mean open arm exploration on the EPM, spatial memory, and learning in the MWM or behavioral despair measured by the FST (p > 0.05). Although the 3-day restraint/tail shock stress model caused stress in the rodents, it did not produce reported PTSD-like anxiety and depression or spatial memory loss. The effect of Pre-L-Th or Post-L-Th treatment, on the neurobehavioral functions could not be effectively evaluated. However, this study provides a foundation for future studies to try different rodent PTSD models to induce PTSD-like neurobehavioral impairments to explore dosage, frequency, as well as the duration of L-Th administration before and/or after the post-traumatic event. The 3-day restraint/tail shock stress model caused stress in the rodents, Pre-L-Theanine treatment preconditioned the PTSD rats to endure stress.
... Phenolic compounds are the secondary metabolites of plants found in a wide range of foods, particularly in red wine, olive oil, green tea, and blueberries (80). In both in vitro and in vivo models, phenolic compounds directly regulate amyloidosis, neuroinflammation, and tau aggregation (80)(81)(82)(83)(84). Several clinical trials have observed the positive cognitive effects of phenolic supplementation in cognitively healthy older adults (85)(86)(87)(88)(89)(90)(91) and those presenting mild to moderate dementia (92)(93)(94)(95)(96)(97). Other trials, however, have failed to demonstrate these beneficial effects in the elderly (98)(99)(100)(101)(102)(103). ...
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Longer life expectancy has led to an increase in the prevalence of age-related cognitive decline and dementia worldwide. Due to the current lack of effective treatment for these conditions, preventive strategies represent a research priority. A large body of evidence suggests that nutrition is involved in the pathogenesis of age-related cognitive decline, but also that it may play a critical role in slowing down its progression. At a population level, healthy dietary patterns interventions, such as the Mediterranean and the MIND diets, have been associated with improved cognitive performance and a decreased risk of neurodegenerative disease development. In the era of evidence-based medicine and patient-centered healthcare, personalized nutritional recommendations would offer a considerable opportunity in preventing cognitive decline progression. N-of-1 clinical trials have emerged as a fundamental design in evidence-based medicine. They consider each individual as the only unit of observation and intervention. The aggregation of series of N-of-1 clinical trials also enables population-level conclusions. This review provides a general view of the current scientific evidence regarding nutrition and cognitive decline, and critically states its limitations when translating results into the clinical practice. Furthermore, we suggest methodological strategies to develop N-of-1 clinical trials focused on nutrition and cognition in an older population. Finally, we evaluate the potential challenges that researchers may face when performing studies in precision nutrition and cognition.
... In the search for a natural anti-AD functional agent, green tea extract (GTE) has been widely reported to have beneficial effects on cognitive function. According to human cohort studies, interventions with GTE showed positive effects on the cognitive function of healthy volunteers and MCI patients [5][6][7]. In addition, the consumption of green tea was closely related to a reduced risk of MCI and dementia [8][9][10]. ...
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Green tea intake is generally recognized as an effective supplement that promotes mental clarity and cognitive function. These health benefits of green tea have been attributed mainly to its effective component, epigallocatechin gallate (EGCG). Because various catechin derivatives potently enhance these health benefits, we manipulated the extraction process with a high-temperature intervention. High-temperature-processed green tea extract (HTP-GTE) showed an elevated proportion of gallocatechin gallate (GCG) content. To investigate the preventive effects of HTP-GTE on cognitive decline, we found its neuroprotective effects against amyloid β (Aβ)-induced neurotoxicity in neurons and clarified that GCG significantly inhibited Aβ aggregation in vitro. Moreover, we showed that HTP-GTE intake attenuated several cognitive-decline phenotypes in a model mouse of Alzheimer’s disease. These beneficial effects of HTP-GTE against cognitive decline were due to the distinctive composition of the extract and suggest the possibility that HTP-GTE supplementation could attenuate cognitive decline of Alzheimer’s disease.
... In a cross-sectional study involving 1003 elderly Japanese subjects, green tea consumption was associated with attenuated cognitive impairment Kuriyama et al., 2006; In an elderly population with clinical mild cognitive impairment, 16 weeks of treatment with a combination of green tea extract with L-theanine, a protein found in green tea, improved memory and selective attention associated with elevated brain theta waves, which is an indicator of cognitive alertness Park et al., 2011 One study involving 27 elderly subjects showed that 2 g/day of green tea powder containing 220.2 mg of catechins did not impact cognitive impairment, despite having a positive effect on oxidative stress Ide et al., 2016 central (CNS) nervous systems, neuroendocrine connections, humoral pathways, cytokines, neuropeptides and other signaling molecules derived from the gut microbiota itself or produced by the enterochromaffin cells in the gut epithelium in response to the gut microbiota (Mayer et al., 2014). There are several independent and distinct pathways that contribute to the GBA's bidirectional signaling including inflammatory mediators, metabolic signaling, oxidative stress markers, stress modulators, neurohormone factors and direct neuronal communication through the vagus nerve (Kohler et al., 2016;Westfall et al., 2017). ...
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The pathophysiology of depression is multifactorial yet generally aggravated by stress and its associated physiological consequences. To effectively treat these diverse risk factors, a broad acting strategy is required and is has been suggested that gut-brain-axis signaling may play a pinnacle role in promoting resilience to several of these stress-induced changes including pathogenic load, inflammation, HPA-axis activation, oxidative stress and neurotransmitter imbalances. The gut microbiota also manages the bioaccessibility of phenolic metabolites from dietary polyphenols whose multiple beneficial properties have known therapeutic efficacy against depression. Although several potential therapeutic mechanisms of dietary polyphenols toward establishing cognitive resilience to neuropsychiatric disorders have been established, only a handful of studies have systematically identified how the interaction of the gut microbiota with dietary polyphenols can synergistically alleviate the biological signatures of depression. The current review investigates several of these potential mechanisms and how synbiotics, that combine probiotics with dietary polyphenols, may provide a novel therapeutic strategy for depression. In particular, synbiotics have the potential to alleviate neuroinflammation by modulating microglial and inflammasome activation, reduce oxidative stress and balance serotonin metabolism therefore simultaneously targeting several of the major pathological risk factors of depression. Overall, synbiotics may act as a novel therapeutic paradigm for neuropsychiatric disorders and further understanding the fundamental mechanisms of gut-brain-axis signaling will allow full utilization of the gut microbiota’s as a therapeutic tool.
... 17,18 It has been demonstrated that green tea has a beneficial role in cognitive functions, specifically in alertness, attention, and memory retention. 19,20 A higher consumption of green tea was not only significantly related to reduced cognitive impairments both in Alzheimer transgenic mice and older adults but also led to higher cognitive performances in healthy subjects. 12,[21][22][23] Recent research indicated that the beneficial impact of green tea on cognition is related to altered brain activity or connections. ...
Article
Background and objectives: Green tea is reported to have wide benefits on psychological states and cognitive functions. Studies that focus on the underlying neural mechanisms of green tea are limited to its single composition while people usually benefit from green tea water that contains various composition. In this study, we examined the human brain activity changes after drinking natural green tea by using regional homogeneity and functional connectivity based on the resting-state functional MRI technique. Methods and study design: Fifteen healthy volunteers participated in two imaging sessions: a control (water) session and a green tea session, each session comprised a predrinking, drinking, and postdrinking section, during the drinking section, the subject consumed 200 mL of green tea infusion or water in 3 to 5 minutes. Then the post-tea and post-water imaging data were selected for regional homogeneity and functional connectivity analysis. Results: Our results revealed that, compared with the control group, the green tea group exhibited an increased regional homogeneity in the frontal, parietal, and occipital areas of the brain, decreased regional homogeneity values in the left cuneus and left lingual gyrus, mainly a decreased functional connectivity in the default mode network, somatosensory, visual cortex, and parieto-frontal areas and enhanced functional connectivity in brain regions associated with memory. Conclusions: This result indicates that green tea consumption impacts the brain activity during resting state.
... Certainly, the effectiveness of such activity is influenced by the duration of treatment, as well as the dosage and form in which antioxidants are administered. In a study by Park et al. [194], 91 persons received diet supplements containing 1440 mg of green tea extract for 16 weeks. The study did not reveal any differences between subjects receiving the supplement or the placebo in terms of memory or selective attention; possibly, the results would be more apparent in a longer supplementation period. ...
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Neurodegenerative diseases are progressive diseases of the nervous system that lead to neuron loss or functional disorders. Neurodegenerative diseases require long-term, sometimes life-long pharmacological treatment, which increases the risk of adverse effects and a negative impact of pharmaceuticals on the patients’ general condition. One of the main problems related to the treatment of this type of condition is the limited ability to deliver drugs to the brain due to their poor solubility, low bioavailability, and the effects of the blood-brain barrier. Given the above, one of the main objectives of contemporary scientific research focuses on the prevention of neurodegenerative diseases. As disorders related to the competence of the antioxidative system are a marker in all diseases of this type, the primary prophylactics should entail the use of exogenous antioxidants, particularly ones that can be used over extended periods, regardless of the patient’s age, and that are easily available, e.g., as part of a diet or as diet supplements. The paper analyzes the significance of the oxidoreductive balance in the pathogenesis of neurodegenerative diseases. Based on information published globally in the last 10 years, an analysis is also provided with regard to the impact of exogenous antioxidants on brain functions with respect to the prevention of this type of diseases.
... Thirdly, ltheanine, a specific amino acid extracted from tea leaves, was suggested to be an intervention for cognitive improvement [46]. In a randomized controlled trial (RCT) study, electroencephalograms showed that participants treated by l-theanine had higher levels of theta waves, interpreted to be an indicator of cognitive alertness, in the temporal, frontal, parietal, and occipital lobes after 3 h of reading compared with the placebo group [47]. Noteworthily, since the beneficial compounds in tea are small, they could cross the blood-brain barrier to reach the brain parenchyma [48,49]. ...
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As a widely consumed beverage, tea boasts diverse health benefits. Herein, we aimed to investigate the association between tea consumption and dementia risk. We conducted a prospective cohort study with 377 592 UK Biobank participants during a 9-year follow-up. Cox regression models adjusted for age, sex, ethnicity, Townsend deprivation index, education, body mass index, lifestyle factors, dietary factors and apolipoprotein E4 status were used to examine the association of tea consumption with dementia risk. Subgroup analyses stratified by age, sex and forms of dementia (Alzheimer’s disease [AD] and vascular dementia [VD]) were performed. Moreover, the restricted cubic splines were used to calculate the nonlinear relationship between daily dosage of tea and dementia risk. After adjustment for all covariates, tea drinkers were 16% (95% confidence interval: 8–23) less likely to develop dementia compared with non-drinkers. Moderate consumption (1–6 cups/day) of tea exerted significant protective effects. Subgroup analyses showed that mid-aged participants or males benefited more from tea consumption. Moreover, moderate drinkers had a 16–19% lower hazard of AD and a 25–29% lower hazard of VD. Furthermore, a U-shaped association between tea consumption and dementia risk was shown (Pnon-linearity = 7E⁻⁰⁴), and the consumption of around three cups per day showed the strongest protective effect. Within 3 cups/day, drinking one extra cup of tea per day brought a 6% reduction of incidence. In conclusion, moderate consumption of tea was significantly associated with a reduced risk of dementia, suggesting that tea consumption could be a modifiable lifestyle factor for dementia.
... A standardized extract containing green tea combined with L-theanine from the tea plant Camellia sinensis (L.) (LGNC-07) has also been shown to improve memory and selective attention. This enhancement was accompanied by an increase in brain theta waves in multiple brain areas (the temporal, frontal, parietal, and occipital areas), which has been related to improved cognitive alertness (Park et al. 2011). Magnetic resonance imaging has also shown changes in short-term plasticity in parietal-frontal brain synergies, accompanied by increased working memory processing in a population that had experimentally consumed a whey-based soft drink containing green tea extract (Schmidt et al. 2014). ...
Article
Substances with modulatory capabilities on certain aspects of human cognition have been revered as nootropics from the dawn of time. The plant kingdom provides most of the currently available nootropics of natural origin. Here, in this systematic review, we aim to provide state-of-the-art information regarding proven and unproven effects of plant-derived nootropics (PDNs) on human cognition in conditions of health and disease. Six independent searches, one for each neurocognitive domain (NCD), were performed in parallel using three independent scientific library databases: PubMed, Cochrane and Scopus. Only scientific studies and systematic reviews with humans published between January 2000 and November 2021 were reviewed, and 256 papers were included. Ginkgo biloba was the most relevant nootropic regarding perceptual and motor functions. Bacopa monnieri improves language, learning and memory. Withania somnifera (Ashwagandha) modulates anxiety and social-related cognitions. Caffeine enhances attention and executive functions. Together, the results from the compiled studies highlight the nootropic effects and the inconsistencies regarding PDNs that require further research.
... Despite the growing evidence from epidemiological (Kakutani, Watanabe, & Murayama, 2019;Mancini et al., 2017) and preclinical studies (Pervin, Unno, Takagaki, Isemura, & Nakamura, 2019;Xicota, Rodriguez-Morato, Dierssen, & de la Torre, 2017), clinical studies on green tea polyphenols on cognitive outcomes are rather scarce. Only two studies have been conducted so far to examine its potential effects on cognitive health, although reporting contrasting results (Ide et al., 2016;Park et al., 2011). A study investigated the effects of a combination of green tea extract and l-theanine on cognition. ...
Article
Dietary polyphenols have been the focus of major interest for their potential benefits on human health. Several preclinical studies have been conducted to provide a rationale for their potential use as therapeutic agents in preventing or ameliorating cognitive decline. However, results from human studies are scarce and poorly documented. The aim of this review was to discuss the potential mechanisms involved in age-related cognitive decline or early stage cognitive impairment and current evidence from clinical human studies conducted on polyphenols and the aforementioned outcomes. The evidence published so far is encouraging but contrasting findings are to be taken into account. Most studies on anthocyanins showed a consistent positive effect on various cognitive aspects related to aging or early stages of cognitive impairment. Studies on cocoa flavanols, resveratrol, and isoflavones provided substantial contrasting results and further research is needed to clarify the therapeutic potential of these compounds. Results from other studies on quercetin, green tea flavanols, hydroxycinnamic acids (such as chlorogenic acid), curcumin, and olive oil tyrosol and derivatives are rather promising but still too few to provide any real conclusions. Future translational studies are needed to address issues related to dosage, optimal formulations to improve bioavailability, as well as better control for the overall diet, and correct target population.
... Enhanced cognition: Park et al, 2011Sedation: Unno et al, 2013Yoto, Motoki, Murao, & Yokogoshi, 2012;Lyon, Kapoor, & Juneja, 2011;Ristner et al, 2010;Nobre, Rao, & Owen, 2008;Lu et al, 2004;Juneja, Chu, Okubo, Nagato, & Yokogoshi, 1999 Suggested daily dose: 50-400 mg Tyrosine Activation: Neri et al, 1995;Mouret et al, 1988;Gelenberg, Wojcik, Gibson, & Wurtman, 1983;Gelenberg, Wojcik, Growdon, Sved, & Wurtman, 1980 Decreased reward-seeking behavior: Blum et al, 1988 Enhanced cognition: Mahoney, Castellani, Kramer, Young, & Lieberman, 2007;Deijen, Wientjes, Vullinghs, Cloin, & Langefeld, 1999;Neri et al, 1995;Deijen & Orlebeke, 1994;Shurtleff, Thomas, Schrot, Kowalski, & Harford, 1994;Reimherr, Wender, Wood, & Ward, 1987;Wood, Reimherr, & Wender, 1984 Psychomotor slowing: Reimherr, Wender, Wood, & Ward, 1987;Wood, Reimherr, & Wender, 1984Sedation: Dollins, Krock, Storm, Wurtman, & Lieberman, 1995Banderet & Lieberman, 1989 Suggested daily dose: 30-150 mg/kg ...
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The author presents the perspective that orthomolecular treatments possess psychoactive effects that result in potentially desirable physiological changes (e.g., sedation, psychomotor slowing, activation, and/or altered sense perception). The psychoactive effects of a broad range of commonly-recommended orthomolecular interventions are listed. This perspective can be integrated into a more expansive understanding of how orthomolecular interventions work, without claiming specific biochemical alterations. Lastly, several key advantages are delineated to support the use of orthomolecular interventions for their psychoactive effects.
... Green tea-derived catechins do not only enhance memory formation, but also rescue impaired cognitive functions due to environmental stressors. Catechin-rich foods have been considered to improve various aspects of cognitive functions in rodents and humans, and some reports suggest that it has positive effects on mild cognitive impairment [69][70][71]. EpiC administration improves spatial memory in mice via an increase in cerebral angiogenesis or a direct effect on neural elements [8]. In Lymnaea, there are some reports for the recovery effect of EpiC on impaired function by environmental stressor [5,38]. ...
Chapter
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Green tea has been used as a medicine in East Asia for thousands of years. Plant-derived compounds called flavanols, which are included in green tea, may have potentials to help maintain healthy brain function. In this chapter, we review the effects of flavanols, e.g. epicatechin (EpiC), on cognitive ability in the pond snail, Lymnaea stagnalis. In this decade, the Lukowiak’s group has tested the effects of EpiC on cognition ability in Lymnaea. In a Lymnaea model system, they showed that EpiC and EpiC-containing foods have a rapid and activity-dependent effect enhancing the formation of long-term memory (LTM) following operant conditioning of aerial respiratory behavior. In the last part of this chapter, we also introduce our study for the effects of EpiC on LTM formation in another model system in Lymnaea. This study showed that EpiC increases the persistence of LTM formed by classical conditioning of feeding behavior, and suggested that EpiC alters some electrophysiological properties of a neuron in the feeding system.
... Most of the polyphenols found in green tea are catechins, mainly epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG) [2,56]. Health benefits of green tea as a drink, or in the form of extract, include improvement in cardiometabolic health [57,58], weight reduction [56] and improved cognitive function [59,60]. Results from this study show that while at baseline the detection of 10 plasma polyphenols was similar across the intervention groups, in polyphenols that significantly differed between groups at the end of the intervention, the MED groups showed higher detection compared with the group actively receiving the least polyphenols. ...
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Background: Polyphenols are secondary metabolites produced by plants to defend themselves from environmental stressors. We explored the effect of Wolffia globosa 'Mankai', a novel cultivated strain of a polyphenol-rich aquatic plant, on the metabolomic-gut clinical axis in vitro, in-vivo and in a clinical trial. Methods: We used mass-spectrometry-based metabolomics methods from three laboratories to detect Mankai phenolic metabolites and examined predicted functional pathways in a Mankai artificial-gut bioreactor. Plasma and urine polyphenols were assessed among the 294 DIRECT-PLUS 18-month trial participants, comparing the effect of a polyphenol-rich green-Mediterranean diet (+1240 mg/polyphenols/day, provided by Mankai, green tea and walnuts) to a walnuts-enriched (+440 mg/polyphenols/day) Mediterranean diet and a healthy controlled diet. Results: Approximately 200 different phenolic compounds were specifically detected in the Mankai plant. The Mankai-supplemented bioreactor artificial gut displayed a significantly higher relative-abundance of 16S-rRNA bacterial gene sequences encoding for enzymes involved in phenolic compound degradation. In humans, several Mankai-related plasma and urine polyphenols were differentially elevated in the green Mediterranean group compared with the other groups (p < 0.05) after six and 18 months of intervention (e.g., urine hydroxy-phenyl-acetic-acid and urolithin-A; plasma Naringenin and 2,5-diOH-benzoic-acid). Specific polyphenols, such as urolithin-A and 4-ethylphenol, were directly involved with clinical weight-related changes. Conclusions: The Mankai new plant is rich in various unique potent polyphenols, potentially affecting the metabolomic-gut-clinical axis.
... 28 Another randomized controlled trial based on 91 older persons with pre-existing mild cognitive impairment indicated that a combination of green tea extract and L-theanine marginally improved the Rey Auditory Verbal Learning Test score. 29 Although these studies were not based on incident dementia as an outcome, these results also suggested a preventive effect of green tea against incident dementia. Further clinical trials are necessary to confirm this preventive effect of green tea extract. ...
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Objective: Biologic studies have shown that certain components of green tea may have protective effects on neurocognition. However, because of the lack of human epidemiologic studies, the impact of green tea consumption on the incidence of dementia has never been confirmed. The objective of this cohort study was to clarify the association between green tea consumption and incident dementia. Methods: In this 5.7-year prospective cohort study, using a questionnaire, information on daily green tea consumption and other lifestyle factors was collected from elderly Japanese individuals aged 65 years or more. Data on incident dementia were retrieved from the public Long-term Care Insurance Database. Results: Among 13,645 participants, the 5.7-year rate of incident dementia was 8.7%. More frequent green tea consumption was associated with a lower risk of incident dementia (hazard ratio for ≥5 cups/day versus <1 cup/day: 0.73; 95% confidence interval: 0.61-0.87). The lower risk of incident dementia was consistent even after selecting participants who did not have subjective memory complaints at the baseline. Conclusion: Green tea consumption is significantly associated with a lower risk of incident dementia.
... On the 4th day of the LH protocol, the rats were tested for escape behavior to evaluate the induction of helplessness. Rats showing more than 20 escape failures during the course of 30 trials were referred to be "helpless" 36,37 . As shown in Fig. S2a-c, the shock protocol effectively induced LH with an incidence rate of 84.2% in vehicle-fed OVX rats ( Fig. S2f-g). ...
Article
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Post-menopausal depression (PMD) is a common psychological disorder accompanied by a cognitive deficit, which is caused by a series of uncontrolled emotional disruptions by strong environmental stressors during menopause. To overcome PMD-induced cognitive deficit, Green tea has been suggested as a dietary supplement because of its ameliorating effect on cognitive dysfunction induced by normal aging or neurodegenerative syndromes; however, its clinical use to improve PMD-accompanied cognitive deficit is still limited due to the controversy for the active ingredients and ambiguous mechanism of its action. Here, we developed modified high-temperature-processed green tea extract (HTP-GTE), which showed lower neuronal toxicity than the conventional green tea extract (GTE). We also demonstrated that HTP-GTE administration prevented the development of learned helplessness (LH) in a rat post-menopausal model. Additionally, HTP-GTE improved LH-induced cognitive impairments simultaneously with rescued the long-term synaptic plasticity. This occurred via the restoration of silent synapse formation by increasing the hippocampal BDNF-tyrosine receptor kinase B pathway in the helpless ovariectomized (OVX) rats. Likewise, we also identified that (−)-gallocatechin gallate was the main contributor of the HTP-GTE effect. Our findings suggested that HTP-GTE has a potential as a preventive nutritional supplement to ameliorate cognitive dysfunctions associated with PMD.
... In a Korean 16-week randomized, double-blind, placebo-controlled trial, the effect of a combination of green tea extract and l-theanine (LGNC-07) on memory and attention in subjects with mild cognitive impairment was investigated in 91 subjects with mild cognitive impairment. 11 The treatment group took 1,680 mg of LGNC-07 and was compared with the placebo group. ...
... 20 Human intervention studies also showed benefits of EGCG. In a randomized, double-blind, placebocontrolled study, 21 the effect of green tea extract (720 mg, twice daily) was studied in 91 mild cognitive impairment (MCI) subjects for 16 weeks. This study showed that green tea extract improved memory and selective attention in subjects with Mini Mental State Examination-Korea scores of 21−23. ...
Article
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Deposition of Aβ42 aggregates in the form of amyloid plaques is a pathological hallmark of Alzheimer’s disease. A desired avenue of intervention is the inhibition of Aβ42 aggregation. Epigallocatechin gallate (EGCG), the main polyphenol in green tea, has been generally considered an inhibitor of Aβ aggregation. However, previous experiments focused on the reduction of the amount of Aβ42 aggregates, while the effect of EGCG on the rate of Aβ42 aggregation was not critically analyzed. Here we performed an experimental evaluation of Aβ42 aggregation kinetics in the absence and presence of EGCG at a wide range of concentrations. We found that EGCG reduced thioflavin T fluorescence in an EGCG concentration-dependent manner, suggesting that EGCG reduced the amount of Aβ42 fibrils. The effect of EGCG on the rate of Aβ42 aggregation appears to be bimodal. We found that higher EGCG-to-Aβ42 ratios promoted the rate of Aβ42 aggregation, while lower EGCG-to-Aβ42 ratios inhibited the aggregation rate. To confirm that the reduction of thioflavin T fluorescence is due to the lowered aggregate quantity, but not due to perturbation of thioflavin T binding to Aβ42 fibrils, we probed the effect of EGCG on Aβ42 aggregation using site-directed spin labeling. Electron paramagnetic resonance of spin-labeled Aβ42 aggregates suggests that high EGCG-to-Aβ42 ratios led to a greatly reduced amount of Aβ42 fibrils, and these aggregates adopt similar structures as the fibrils in the no-EGCG sample. Potential implications of this work in designing prevention or therapeutic strategies using EGCG are discussed.
... Of these, 20 studies were excluded, because the outcomes were not cognitive disorders considered in this metaanalysis [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Another 11 studies were excluded due to no available estimates or the data for calculating the estimates [21][22][23][24][25][26][27][28][29][30][31]. Additional 5 studies were excluded by reason of unevaluated effect of tea with the influence of other food like coffee or vegetables [32][33][34][35][36]. ...
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The reasons for exclusion of the 42 full-text reviewed studies. (PDF)
... L-теанин -аминокислота, аналог глутамина и глутамата, первоначально найденная в экстрактах зеленого чая. Теанин может пересекать гематоэнцефалический барьер и характеризуется психоактивными свойствами [52], способствуя снижению умственного и физического стресса [53], депрессивной симптоматики и улучшая когнитивные способности [54]. Теанин характеризуется слабым сродством к рецепторам глутамата [55] и может частично блокировать избыточную активацию глутаматных рецепторов. ...
Article
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Aim: A complex study of pharmacological properties of magnesium pyroglutamate using the modern methods of chemoinformatics and bioinformatics. Material and methods: Pharmacological properties of magnesium pyroglutamate were studied using chemoinformatic and bioinformatic analyses. Results: Neurotropic effects of magnesium pyroglutamate are due to an influence on the synthesis of neuropeptides containing pyroglutamate (orexin, thyroliberin, neurotensin etc) and due to the similarity between pyroglutamate-anion with some neuroactive components (L-theanine, 2-pirrolydinone, piracetam). Conclusion: The results of the study suggest neuroprotective, sedative and antidepressive properties of magnesium pyroglutamate which are realized by pyroglutamate-anion in the synergism with magnesium cation.
... Two double-blind, randomized, placebo-controlled human clinical trials which studied the effect of black tea on attention using tasks measuring ability to switch and the intersensoryattention test reported that black tea significantly enhance accuracy on switching (study 1, p < 0.002; study 2, p = 0.007) and self-reported alertness [96]. In support of this, a small randomized, double-blind, placebo-controlled study also reported beneficial effects on cognition in mild cognitive impairment [162]. Although these mechanisms are still unclear, polyphenols within tea may have a therapeutic potential for AD [145]. ...
Chapter
Reactive oxygen species (ROS), when excessively produced in the brain, lead to oxidative stress and result in neurotoxicity. The brain in particular is prone to this oxidative stress phenomenon. Impairments in memory and cognition are hallmarks of progressive neurodegenerative diseases. Though numerous researchers round the world are trying to find effective therapeutic options and elucidate the molecular events involved in different neurodegenerative disorders, nevertheless an extensive knowledge about the therapeutic targets involved in the pathogenesis of such neurodegenerative disorders is still limited. In this book chapter, we aim to offer a detailed discussion on the neuroprotective effects of different classes of naturally occurring antioxidants (flavonoid and non-flavonoid polyphenols, phenolic acids, organosulfur compounds, etc.) against various neurological disorders, especially cognitive and movement disorders. Oxidative stress (elevation of intracellular ROS level) is a major cause in the development and progression of neurological diseases such as neurodegenerative diseases, movement disorders, and so on. Therefore, targeting these diseases with antioxidants may be expected to be a fruitful solution. Many scientific reports suggest that the use of natural compounds is beneficial in the treatment of neurodegenerative disorders if the relationship between neuroprotective functions and their potential therapeutic importance can be figured out. These natural therapeutic molecules can, therefore, serve as conventional and unconventional medicine in the clinical outlook. Herein we try to give an overall idea about the prospects of several nutraceuticals in the field of neurological diseases.
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Green tea (Camellia sinensis L.) has been famous as a beverage and natural medicine. It contains a broad range of primary and secondary metabolites i.e. polyphenols. Nuclear Magnetic Resonance (NMR) has been widely used for metabolic profiling in medicinal plants. It provides a very fast and detailed analysis of the biomolecular composition of crude extracts. Moreover, an NMR spectrum is a physical characteristic of a compound and thus highly reproducible. Therefore, this study aims to profile metabolites of three different varieties of green tea C. Sinensis grown in Kemuning, Middle Java. Three varieties of green tea collected on Kemuning (TR1 2025, Gambung 4/5, and Chiaruan 143) were used in this study. 1H-NMR spectra were recorded at 230C on a 400 MHz Agilent WB (Widebore). The analysis was performed on dried green tea leaves and analyzed by 1H-NMR, 2D-J-resolved and 1H-1H correlated spectroscopy (COSY). MestRenova version 11.0.0 applied to identify metabolites in samples. A ¹H-NMR spectrum of tea showed amino acids and organic acids signal at the area δ 0.8–4.0. These were theanine, alanine, threonine, succinic acid, aspartic acid, lactic acid. Anomeric protons of carbohydrate were shown by the region of β-glucose, α-glucose, fructose and sucrose. The phenolic region was depicted at area δ 5.5-8.5. Epigallocatechin derivates and caffeine were detected in the tea leaves. The detail compound identification was observed and discussed in the text.
Article
Dementia and diabetes mellitus are prevalent disorders in the elderly population. While recognized as two distinct diseases, diabetes has more recently recognized as a significant contributor to risk for developing dementia, and some studies make reference to type 3 diabetes, a condition resulting from insulin resistance in the brain. Alzheimer's disease, the most common form of dementia, and diabetes, interestingly, share underlying pathological processes, commonality in risk factors, and, importantly, pathways for intervention. Tea has been suggested to possess potent antioxidant properties rich in phytochemicals including, flavonoids, tannins, caffeine, polyphenols, boheic acid, theophylline, theobromine, anthocyanins, gallic acid, and finally epigallocatechin-3-gallate, considered the most potent active ingredient. Flavonoid phytochemicals, known as catechins, within tea offer potential benefits for reducing the risk of diabetes and Alzheimer's disease by targeting common risk factors, including obesity, hyperlipidemia, hypertension, cardiovascular disease, and stroke. Studies also show that catechins may prevent the formation of amyloid-β plaques and enhance cognitive functions, and thus may be useful in treating patients who have Alzheimer's disease or dementia. Furthermore, other phytochemicals found within tea offer important antioxidant properties along with innate properties capable of modulating intracellular neuronal signal transduction pathways and mitochondrial function.
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The ASN Board of Directors appointed the Nutrition Research Task Force to develop a report on scientific methods used in nutrition science to advance discovery, interpretation, and application of knowledge in the field. The genesis of this report was growing concern about the tone of discourse among nutrition professionals and the implications of acrimony on the productive study and translation of nutrition science. Too often, honest differences of opinion are cast as conflicts instead of areas of needed collaboration. Recognition of the value (and limitations) of contributions from well-executed nutrition science derived from the various approaches used in the discipline, as well as appreciation of how their layering will yield the strongest evidence base, will provide a basis for greater productivity and impact. Greater collaborative efforts within the field of nutrition science will require an understanding that each method or approach has a place and function that should be valued and used together to create the nutrition evidence base. Precision nutrition was identified as an important emerging nutrition topic by the preponderance of task force members, and this theme was adopted for the report because it lent itself to integration of many approaches in nutrition science. Although the primary audience for this report is nutrition researchers and other nutrition professionals, a secondary aim is to develop a document useful for the various audiences that translate nutrition research, including journalists, clinicians, and policymakers. The intent is to promote accurate, transparent, verifiable evidence-based communication about nutrition science. This will facilitate reasoned interpretation and application of emerging findings and, thereby, improve understanding and trust in nutrition science and appropriate characterization, development, and adoption of recommendations.
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Dementia is a common and debilitating syndrome with enormous impact on individuals and societies. Preventing disease onset or progression would translate to public health and societal benefits. In this review, we discuss the latest evidence on interventions that may show promise for the prevention of cognitive decline. We appraise existing evidence primarily drawn from randomized controlled trials, systematic reviews, and meta-analyses, but also highlight observational studies in humans and relevant work in model organisms. Overall, there is currently limited evidence to support a cause–effect relationship between any preventive strategy and the development or progression of dementia. However, studies to date suggest that a multifactorial intervention comprising regular exercise and healthy diet, along with the amelioration of vascular risk factors, psychosocial stress, and major depressive episodes may be most promising for the prevention of cognitive decline. We discuss the challenges, future directions, and implications of this line of research.
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Objectives: To assess the effects of a combination of omega 3 essential fatty acids, green tea catechins, and ginsenosides on cognition and brain functioning in healthy older adults. Design: Double-blind, placebo-controlled, crossover design randomized controlled trial with 26-day intervention phases and a 30-day washout period. Setting: The Institute for Dementia Research and Prevention at the Pennington Biomedical Research Center. Participants: Ten independently-living, cognitively-healthy older adults (mean age: 67.3 + 2.01 years). Intervention: Daily consumption of an investigational product (trade name "Cerbella TM") consisting of an emulsified liquid combination of standardized fish oil, panax ginseng extract, and green tea catechins in a flavored base of lecithin phospholipids optimized to maximize bioavailability of the active ingredients. Measurements: Before and after supplementation with the investigational product or placebo, participants completed cognitive tests including the Mini Mental State Exam (MMSE), Stroop test, Digit Symbol Substitution Test (DSST), and Immediate and Delayed Recall tests, as well as functional magnetic resonance imaging (fMRI) during a standard cognitive task switching paradigm. Results: Performance on the MMSE, Stroop test, and DSST increased significantly over one month of supplementation with the investigational product (one-sample t tests, p<.05) although differences between these changes and corresponding changes during supplementation with placebo were not significant (two-sample t tests, p>.05). During supplementation with the investigational product, brain activation during task performance increased significantly more than during supplementation with placebo in brain regions known to be activated by this task (anterior and posterior cingulate cortex). Functional connectivity during task execution between task regions (middle frontal gyrus and anterior cingulate cortex) increased significantly during supplementation with the investigational product, relative to placebo. Functional connectivity during rest between task regions (precentral gyrus and middle frontal gyrus) and default mode network regions (medial frontal gyrus and precuneus) decreased during supplementation with the investigational product relative to placebo, suggesting greater segregation of task and rest related brain activity. Conclusion: One-month supplementation with a combination of omega 3 essential fatty acids, green tea catechins, and ginsenosides was associated with suggestive changes in cognitive functioning as well as modification of brain activation and brain functional connectivity in cognitively healthy older adults.
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Functional tea beverages have emerged as a novel approach to achieving health benefits associated with tea. The use of metabolomics may improve the evaluation of their consumption and their effects. The current study aimed to explore the urinary signature of the exposure to a functional high-catechin tea (HCT) using untargeted NMR-based metabolomics. Ten volunteers participated in a crossover intervention study. Individuals consumed an HCT or a control beverage over a period of 28 days. Multilevel partial least squares discriminant analysis (ML-PLS-DA) was used for paired comparisons. A further crossover model was performed to assess the significant changes. The consumption of the HCT resulted in the excretion of theanine, epicatechin, pyrogallol sulfate, higher levels of 3-methyl-2-oxovalerate and succinate, as well as unknown compounds. In conclusion, the present work established novel urinary signatures of a functional drink. Such signatures may be potential biomarkers and/or reflect certain benefits of functional tea beverages.
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Meta-analyses of tea consumption and reduced risk of Parkinson's disease have thrown light in the pathway of exploring beneficial properties of tea components. On the basis of dry mass, a typical black or green tea beverage contains approximately 6% of free amino acids, which impart high quality, taste and distinctive aroma to the tea infusion. L-theanine (chemically known as γ-glutamylethylamide) is a non-proteinogenic amino acid of tea that takes part in the biosynthesis of its polyphenols. Recently discovered neuroprotective effects of L-theanine can be attributed to its structural analogy with glutamate, the principal excitatory neurotransmitter in brain. This unique amino acid also bears a potential to ameliorate the pathophysiological changes associated with Parkinson's disease as it displays antioxidant and anti-inflammatory properties, improves motor behavioral abnormalities, increases dopamine availability and may cause a favorable downshift in neurodegeneration due to glutamate excitotoxicity. To gain an explicit understanding of the role of L-theanine, this review article is the first one to focus on its mechanism of neuromodulatory action and to critically evaluate the possibilities of employing this bioactive amide in the forage of anti-Parkinsonian medication. We also hypothesize the idea of L-theanine being a potent natural agent against L-DOPA induced dyskinesia, since long-term reliance on dopamine replacement therapy is linked with elevation in glutamate receptor activity.
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Matcha is a popular nutritious food ingredient with strong health benefits. The interplay between matcha and gluten is essential for developing high-quality matcha-noodles. Herein, the effects of matcha and its active components, l-theanine and tea polyphenol, on the structural and rheological properties of gluten had been investigated. The results showed that matcha weakened the dough strength by reducing disulfide bonds and hindering the formation of gluten network. However, l-theanine enhanced the ductility of dough by forming extra β-sheets and disulfide bonds, whereas tea polyphenol increased its toughness by forming numerous intermolecular hydrogen bonds with gluten to stabilize the “grid” structure. The underlying intermolecular mechanisms between gluten and l-theanine or tea polyphenol were clearly established. This study has provided valuable reference to produce nutritious noodles products with matcha or its active components.
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This book covers all areas of agricultural sciences and other related fields. The contributions by the authors include tomatoes, genetic transformation, GUS gene, tea, Camellia sinensis, flower, honey, biopesticides, efficacy, food production, neem, pesticides, banana, postharvest life, green tea, Hausa potato, roots, hydroponics, leaf scald, smut, pokkah boeng, agro-ecology, erosion, soil conservation, abiotic stress, root system, Saccharum spp., Zucchini, attacked fruits, coastal forests, forest ecosystem, nitrogen load, nutrient etc. This book contains various materials suitable for students, researchers and academicians in the field of agricultural sciences.
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Chronic adolescent exposure to Δ-9-Tetrahydrocannabinol (THC) is linked to elevated neuropsychiatric risk and induces neuronal, molecular and behavioural abnormalities resembling neuropsychiatric endophenotypes. Previous evidence has revealed that the mesocorticolimbic circuitry, including the prefrontal cortex (PFC) and mesolimbic dopamine (DA) pathway are particularly susceptible to THC-induced pathological alterations, including dysregulation of DAergic activity states, loss of PFC GABAergic inhibitory control and affective and cognitive abnormalities. There are currently limited pharmacological intervention strategies capable of preventing THC-induced neuropathological adaptations. L-theanine is an amino acid analogue of L-glutamate and L-glutamine derived from various plant sources, including green tea leaves. L-theanine has previously been shown to modulate levels of GABA, DA and glutamate in various neural regions and to possess neuroprotective properties. Using a pre-clinical model of adolescent THC exposure in male rats, we report that L-theanine pre-treatment prior to adolescent THC exposure is capable of preventing long-term, THC-induced dysregulation of both PFC and VTA DAergic activity states, a neuroprotective effect which persists into adulthood. In addition, pre-treatment with L-theanine blocked THC-induced downregulation of local GSK-3 and Akt signaling pathways directly in the PFC, two biomarkers previously associated with cannabis-related psychiatric risk and sub-cortical DAergic dysregulation. Finally, L-theanine powerfully blocked the development of both affective and cognitive abnormalities commonly associated with adolescent THC exposure, further demonstrating functional and long-term neuroprotective effects of L-theanine in the mesocorticolimbic system.SIGNIFICANCE STATEMENTWith the increasing trend of cannabis legalization and consumption during adolescence, it is essential to expand knowledge on the potential effects of adolescent cannabis exposure on brain development and identify potential pharmacological strategies to minimize THC-induced neuropathology. Previous evidence demonstrates that adolescent THC exposure induces long-lasting affective and cognitive abnormalities, mesocorticolimbic dysregulation and schizophrenia-like molecular biomarkers that persist into adulthood. We demonstrate for the first time that L-theanine, an amino acid analogue of L-glutamate and L-glutamine, is capable of preventing long-term THC side-effects. L-theanine prevented development of THC-induced behavioral aberrations, blocked cortical downregulation of local GSK-3 and Akt signaling pathways and normalized dysregulation of both PFC and VTA DAergic activity, demonstrating powerful and functional neuroprotective effects against THC-induced developmental neuropathology.
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Background and purpose: Patients with pulmonary arterial hypertension (PAH) frequently present with anxiety, depression, autonomic, and cognitive deterioration, which may indicate brain changes in regions that control these functions. However, the precise regional brain-injury in sites that regulate cognitive, autonomic, and mood functions in PAH remains unclear. We examined the shifts in regional gray matter (GM) volume, using high-resolution T1-weighted images, and brain tissue alterations, using T2-relaxometry procedures, in PAH compared to healthy subjects. Methods: We collected two high-resolution T1-weighted series, and proton-density and T2-weighted images using a 3.0-Tesla magnetic resonance imaging scanner from 9 PAH and 19 healthy subjects. Both high-resolution T1-weighted images were realigned and averaged, partitioned to GM tissue type, normalized to a common space, and smoothed. Using proton-density and T2-weighted images, T2-relaxation maps were calculated, normalized to a common space, and smoothed. Whole-brain GM volume and T2-relaxation maps were compared between PAH and controls using analysis of covariance (covariates, age, sex, and total-brain-volume; false discover rate corrections). Results: Significantly decreased GM volumes, indicating tissue injury, emerged in multiple brain regions, including the hippocampus, insula, cerebellum, parahippocampus, temporal, frontal, and occipital gyri, cingulate, amygdala, and thalamus. Higher T2-relaxation values, suggesting tissue damage, appeared in the cerebellum, hippocampus, parahippocampus, frontal, lingual, and temporal and occipital gyri, and cingulate areas in PAH compared to healthy subjects. Conclusions: PAH patients showed significant GM injury and brain tissue changes in sites that regulate cognition, autonomic, and mood functions. These findings indicate a brain structural basis for functional deficits in PAH patients.
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Tea is the most consumed beverage worldwide, and l-theanine in tea leaves significantly affects their flavor and market quality. We have developed and validated a fast and reliable gas chromatographic method with flame ionization detection (GC-FID) to quantify l-theanine after its extraction from Camellia sinensis (tea plant) and derivatization. The procedure was completed in 40 min, from extraction to chromatographic analysis, with a recovery rate of more than 93% and allowing a high sample throughput. The GC-FID intraday precision was within 0.57-2.28%, while the interday precision ranged from 1.57 to 13.48%. The intraday accuracy ranged from -6.84 to 5.26%, while the interday accuracy ranged from -1.08 to 3.12%. The limit of detection was 2.28 μg/mL, and the limit of quantification was 6.47 μg/mL. The GC-FID method was validated by high-performance liquid chromatography with UV detection (HPLC-UV) and was used to investigate the biosynthesis and regulation of l-theanine in tea plants. We found that plants fed with ethylamine significantly increased l-theanine concentrations in roots, while exogenous supplementation of glutamic acid, carbamide, and glutamine did not significantly affect the l-theanine level in roots. Our results also indicated that roots were not indispensable for the biosynthesis of l-theanine, which was detected in undifferentiated embryonic calluses in concentrations (g/100 g dry weight) as high as in leaves of whole plants (1.67 and 1.57%, respectively) and without any exogenous theanine precursor supplementation.
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Objective: l-theanine, an amino acid uniquely contained in green tea (Camellia sinensis), has been suggested to have various psychotropic effects. This study aimed to examine whether l-theanine is effective for patients with major depressive disorder (MDD) in an open-label clinical trial. Methods: Subjects were 20 patients with MDD (four males; mean age: 41.0±14.1 years, 16 females; 42.9±12.0 years). l-theanine (250 mg/day) was added to the current medication of each participant for 8 weeks. Symptoms and cognitive functions were assessed at baseline, 4, and 8 weeks after l-theanine administration by the 21-item version of the Hamilton Depression Rating Scale (HAMD-21), State-Trait Anxiety Inventory (STAI), Pittsburgh Sleep Quality Index (PSQI), Stroop test, and Brief Assessment of Cognition in Schizophrenia (BACS). Results: HAMD-21 score was reduced after l-theanine administration (p=0.007). This reduction was observed in unremitted patients (HAMD-21>7; p=0.004) at baseline. Anxiety-trait scores decreased after l-theanine administration (p=0.012) in the STAI test. PSQI scores also decreased after l-theanine administration (p=0.030) in the unremitted patients at baseline. Regarding cognitive functions, response latency (p=0.001) and error rate (p=0.036) decreased in the Stroop test, and verbal memory (p=0.005) and executive function (p=0.016) were enhanced in the BACS test after l-theanine administration. Conclusion: Our study suggests that chronic (8-week) l-theanine administration is safe and has multiple beneficial effects on depressive symptoms, anxiety, sleep disturbance and cognitive impairments in patients with MDD. However, since this is an open-label study, placebo-controlled studies are required to consolidate the effects.
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Recent neuropharmacological research has suggested that certain constituents of tea may have modulatory effects on brain state. The bulk of this research has focused on either L-theanine or caffeine ingested alone (mostly the latter) and has been limited to behavioral testing, subjective rating, or neurophysiological assessments during resting. Here, we investigated the effects of both L-theanine and caffeine, ingested separately or together, on behavioral and electrophysiological indices of tonic (background) and phasic (event-related) visuospatial attentional deployment. Subjects underwent 4 d of testing, ingesting either placebo, 100 mg of L-theanine, 50 mg of caffeine, or these treatments combined. The task involved cued shifts of attention to the left or right visual hemifield in anticipation of an imperative stimulus requiring discrimination. In addition to behavioral measures, we examined overall, tonic attentional focus as well as phasic, cue-dependent anticipatory attentional biasing, as indexed by scalp-recorded alpha-band (8-14 Hz) activity. We found an increase in hit rate and target discriminability (d') for the combined treatment relative to placebo, and an increase in d' but not hit rate for caffeine alone, whereas no effects were detected for L-theanine alone. Electrophysiological results did not show increased differential biasing in phasic alpha across hemifields but showed lower overall tonic alpha power in the combined treatment, similar to previous findings at a larger dosage of L-theanine alone. This may signify a more generalized tonic deployment of attentional resources to the visual modality and may underlie the facilitated behavioral performance on the combined ingestion of these 2 major constituents of tea.
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It has been reported that brain factor-7 (BF-7) extracted from Bombyx mori improves cognitive functions in normal juveniles and adults as well as cognitively impaired patients. Clinical studies with normal children evaluated the role of BF-7 on brain function in these patients. The objective of this study was to improve cognitive functions of normal schoolchildren with BF-7. Forty-six normal healthy children were divided into two treatment groups: BF-7 (9.9 +/- 1.18 years old; 9 boys, 14 girls) and placebo (9.8 +/- 1.03 years old; 10 boys, 13 girls). The Color Trails Making Test was used to measure the efficacy of BF-7 on cognition and attention. Results showed that BF-7 reduced the response time by an average of 23% for the Color Trails Making Test. Moreover, BF-7 improved the accuracy of the task around twofold. The results reveal that BF-7 improves brain function for attention and cognitive flexibility in children.
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Of a representative, racially mixed community sample of older adults in North Carolina, 59% of Whites and 49% of African Americans reported worsening memory. The complaint about memory was positively correlated with age, depressive symptomatology, and physical function but not with level of cognitive function as measured by the Short Portable Mental Status Questionnaire (SPMSQ) at baseline. In a controlled analysis of longitudinal data, initial SPMSQ score, age, African American race, lower education, depressive symptomatology, and physical deficits at baseline, but not memory complaint, predicted a decline in cognitive function as measured by the SPMSQ 3 years later. Whereas African Americans were less likely to complain of deterioration in memory, actual decline as measured by the SPMSQ was greater for African Americans than for Whites.
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Subjects with a mild cognitive impairment (MCI) have a memory impairment beyond that expected for age and education yet are not demented. These subjects are becoming the focus of many prediction studies and early intervention trials. To characterize clinically subjects with MCI cross-sectionally and longitudinally. A prospective, longitudinal inception cohort. General community clinic. A sample of 76 consecutively evaluated subjects with MCI were compared with 234 healthy control subjects and 106 patients with mild Alzheimer disease (AD), all from a community setting as part of the Mayo Clinic Alzheimer's Disease Center/Alzheimer's Disease Patient Registry, Rochester, Minn. The 3 groups of individuals were compared on demographic factors and measures of cognitive function including the Mini-Mental State Examination, Wechsler Adult Intelligence Scale-Revised, Wechsler Memory Scale-Revised, Dementia Rating Scale, Free and Cued Selective Reminding Test, and Auditory Verbal Learning Test. Clinical classifications of dementia and AD were determined according to the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition and the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria, respectively. The primary distinction between control subjects and subjects with MCI was in the area of memory, while other cognitive functions were comparable. However, when the subjects with MCI were compared with the patients with very mild AD, memory performance was similar, but patients with AD were more impaired in other cognitive domains as well. Longitudinal performance demonstrated that the subjects with MCI declined at a rate greater than that of the controls but less rapidly than the patients with mild AD. Patients who meet the criteria for MCI can be differentiated from healthy control subjects and those with very mild AD. They appear to constitute a clinical entity that can be characterized for treatment interventions.
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Results of previous studies suggest that memory complaints may predict cognitive decline and dementia among elderly people in whom cognitive impairment is already apparent. However, cognitive decline is often a gradual process, and elderly people may notice that their memory deteriorates before mental status tests are able to detect any change in cognitive functioning. Therefore, the authors hypothesized that memory complaints would predict incident Alzheimer's disease in elderly subjects with no signs of cognitive impairment. In the community-based Amsterdam Study of the Elderly, a sample of 3,778 nondemented persons, 65 to 84 years old, was selected and divided into two cognitive categories: normal (Mini-Mental State scores of 26-30) and borderline and impaired (Mini-Mental State scores less than 26). At baseline, the presence or absence of memory complaints was assessed. At follow-up, incident cases of Alzheimer's disease were diagnosed in a two-step procedure. After an average of 3.2 years, 2,169 persons were reevaluated, of whom 77 had incident Alzheimer's disease. Multivariate logistic regression analyses showed that memory complaints were associated with incident Alzheimer's disease in subjects with normal baseline cognition but not in subjects with impaired baseline cognition. The findings of this study suggest that memory complaints are a relatively strong predictor of incident Alzheimer's disease in older persons in whom cognitive impairment is not yet apparent. Furthermore, they suggest that older persons may be aware of a decline in cognition at a time when mental status tests are still unable to detect a decline from premorbid functioning.
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Mild cognitive impairment (MCI) is considered to be a transitional stage between aging and Alzheimer disease (AD). To determine whether MCI represents early-stage AD by examining its natural history and neuropathologic basis. A prospective clinical and psychometric study of community-living elderly volunteers, both nondemented and minimally cognitively impaired, followed up for up to 9.5 years. Neuropathologic examinations were performed on participants who had undergone autopsy. An AD research center. All participants enrolled between July 1990 and June 1997 with Clinical Dementia Rating (CDR) scores of 0 (cognitively healthy; n = 177; mean age, 78.9 years) or 0.5 (equivalent to MCI; n = 277; mean age, 76.9 years). Based on the degree of clinical confidence that MCI represented dementia of the Alzheimer type (DAT), 3 subgroups of individuals with CDR scores of 0.5 were identified: CDR 0.5/DAT, CDR 0.5/incipient DAT, and CDR 0.5/uncertain dementia. Progression to the stage of CDR 1, which characterizes mild definite DAT. Survival analysis showed that 100% of CDR 0.5/DAT participants progressed to greater dementia severity over a 9.5-year period. At 5 years, rates of progression to a score of CDR 1 (or greater) for DAT were 60.5% (95% confidence interval [CI], 50.2%-70.8%) for the CDR 0.5/DAT group, 35.7% (95% CI, 21.0%-50.3%) for the CDR 0.5/incipient DAT group, 19.9% (95% CI, 8.0%-31.8%) for the CDR 0.5/uncertain dementia group, and 6.8% (95% CI, 2.2%-11.3%) for CDR 0/controls. Progression to greater dementia severity correlated with degree of cognitive impairment at baseline. Twenty-four of the 25 participants with scores of CDR 0.5 had a neuropathologic dementing disorder, which was AD in 21 (84%). Individuals currently characterized as having MCI progress steadily to greater stages of dementia severity at rates dependent on the level of cognitive impairment at entry and they almost always have the neuropathologic features of AD. We conclude that MCI generally represents early-stage AD.
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Ginkgo biloba extract (EGb) from the world's oldest living tree has been reputed to ameliorate cognitive decline in the elderly and slow cognitive deterioration in patients with dementia of the Alzheimer's type. EGb remains as one of the most popular plant extracts to alleviate symptoms associated with a range of cognitive disorders such as Alzheimer's disease, vascular dementia and age-related amnesic conditions. EGb is known to contain a range of chemically active components that have antagonistic effects on platelet-activating factor, free-radical scavenging activity and direct effects on the cholinergic neurotransmitter system. Recently there has been much speculation, that EGb may act as a 'smart drug' or nootropic agent in the healthy young to improve intelligence. We conducted a 30-d randomized, double-blind, placebo-controlled clinical trial in which 61 participants were administered a battery of validated neuropsychological tests before and after treatment. Statistical analysis indicated significant improvements in speed of information processing working memory and executive processing attributable to the EGb.
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The field of aging and dementia is focusing on the characterization of the earliest stages of cognitive impairment. Recent research has identified a transitional state between the cognitive changes of normal aging and Alzheimer's disease (AD), known as mild cognitive impairment (MCI). Mild cognitive impairment refers to the clinical condition between normal aging and AD in which persons experience memory loss to a greater extent than one would expect for age, yet they do not meet currently accepted criteria for clinically probable AD. When these persons are observed longitudinally, they progress to clinically probable AD at a considerably accelerated rate compared with healthy age-matched individuals. Consequently, this condition has been recognized as suitable for possible therapeutic intervention, and several multicenter international treatment trials are under way. Because this is a topic of intense interest, a group of experts on aging and MCI from around the world in the fields of neurology, psychiatry, geriatrics, neuropsychology, neuroimaging, neuropathology, clinical trials, and ethics was convened to summarize the current state of the field of MCI. Participants reviewed the world scientific literature on aging and MCI and summarized the various topics with respect to available evidence on MCI. Diagnostic criteria and clinical outcomes of these subjects are available in the literature. Mild cognitive impairment is believed to be a high-risk condition for the development of clinically probable AD. Heterogeneity in the use of the term was recognized, and subclassifications were suggested. While no treatments are recommended for MCI currently, clinical trials regarding potential therapies are under way. Recommendations concerning ethical issues in the diagnosis and the management of subjects with MCI were made.
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Postmenopausal estrogen therapy has been posited to have some beneficial effects on aging processes, but its use has risks. Isoflavones, estrogenlike compounds naturally occurring in plant foods, might confer positive effects with fewer adverse effects. To investigate whether soy protein with isoflavones improves cognitive function, bone mineral density, and plasma lipids in postmenopausal women. Double-blind, randomized, placebo-controlled trial of 202 healthy postmenopausal women aged 60 to 75 years, recruited from a population-based sample in the Netherlands, conducted between April 2000 and September 2001. Participants were randomly assigned to receive 25.6 g of soy protein containing 99 mg of isoflavones (52 mg genistein, 41 mg daidzein, and 6 mg glycetein or total milk protein as a powder on a daily basis for 12 months. Cognitive function was assessed using the following instruments: dementia, Mini-Mental State Examination; memory, Rey Auditory Verbal Learning Test, immediate recall, delayed recall, and recognition, the Digit Span forward and reversed, and the Doors test; complex attention tasks, Digit Symbol Substitution and Trailmaking, A1, A2, and B; and verbal skills, Verbal Fluency A and N, animals and occupations, and the Boston Naming Task. Bone mineral density of the hip and lumbar spine was assessed using dual-energy x-ray absorptiometry scanning. Lipid assessment included lipoprotein(a), total cholesterol, low-density lipoprotein, high-density lipoprotein, and triglycerides. A total of 175 women completed the baseline and at least 1 postintervention analysis and were included in the modified intent-to-treat analysis. Adherence was good (median plasma genistein levels, 17.2 and 615.1 nmol/L for placebo and soy group, respectively). Cognitive function, bone mineral density, or plasma lipids did not differ significantly between the groups after a year. This double-blind randomized trial does not support the hypothesis that the use of soy protein supplement containing isoflavones improves cognitive function, bone mineral density, or plasma lipids in healthy postmenopausal women when started at the age of 60 years or later.
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L-Theanine (delta-glutamylethylamide) is one of the predominant amino acids ordinarily found in green tea, and historically has been used as a relaxing agent. The current study examined the acute effects of L-theanine in comparison with a standard benzodiazepine anxiolytic, alprazolam and placebo on behavioural measures of anxiety in healthy human subjects using the model of anticipatory anxiety (AA). Sixteen healthy volunteers received alprazolam (1 mg), L-theanine (200 mg) or placebo in a double-blind placebo-controlled repeated measures design. The acute effects of alprazolam and L-theanine were assessed under a relaxed and experimentally induced anxiety condition. Subjective self-reports of anxiety including BAI, VAMS, STAI state anxiety, were obtained during both task conditions at pre- and post-drug administrations. The results showed some evidence for relaxing effects of L-theanine during the baseline condition on the tranquil-troubled subscale of the VAMS. Alprazolam did not exert any anxiolytic effects in comparison with the placebo on any of the measures during the relaxed state. Neither L-theanine nor alprazalam had any significant anxiolytic effects during the experimentally induced anxiety state. The findings suggest that while L-theanine may have some relaxing effects under resting conditions, neither L-theanine not alprazolam demonstrate any acute anxiolytic effects under conditions of increased anxiety in the AA model.
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Previous research has found that depression is a major cause of memory complaints. However, there is evidence that memory complaints also weakly predict cognitive decline and dementia. The present study examined a range of possible determinants of memory complaints, covering psychiatric and personality factors, medical history, cognitive test performance, and biological risk factors for dementia (APOE genotype, hippocampus and amygdala volumes, and white-matter hyperintensities). A community survey was carried out with 2546 persons aged 60-64 years living in Canberra and Queanbeyan, Australia. Participants were asked about memory problems which interfered with daily life and whether medical help had been sought. A randomly selected subsample of 476 persons was given a brain MRI scan. Participants with memory complaints were found to have poorer memory test performance, more depression and anxiety symptoms, have higher scores on personality traits involving negative affect, and to have worse physical health. Multivariate analyses showed that measures of cognitive performance did not make a unique contribution to the prediction of memory complaints above that of the other categories of predictors. Those with memory complaints did not differ on any of the biological risk factors for dementia. In a community sample aged 60-64 years, memory complaints were most closely related to psychiatric symptoms, personality characteristics and poor physical health. There was no evidence of brain changes indicating early dementia.
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Yukmijihwang-tang (YMJ), also known as Luweidihuang-tang in China, has been widely used as a general herbal tonic for hundreds of years in many Asian countries. This study examines whether YMJ derivatives (YMJd) enhance cognitive ability in normal human subjects and discusses its potential as treatment for dementia patients with deficient cognitive ability. Subjects were divided into two groups, the placebo-treated group (n = 15) and the YMJd-treated group (n = 20). K-WAIS tests, a Korean version of an individual intelligence quotient (IQ) test, and a P300 latency assessment of event-related potential (ERP) were conducted in order to measure changes in cognitive ability before and after 6 weeks of YMJd treatment. The K-WAIS mean scores of the group treated with YMJd were significantly higher than those of the placebo group (p < 0.05), and their mean P300 latency was substantially shorter (p < 0.005). These results suggest that YMJd treatment accelerates the speed of information processing and enhances cognitive ability. YMJd treatment may help dementia patients or the elderly recover from cognition deficiencies or degeneration in clinic.
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Laboratory research suggests that tea has potential neurocognitive protective effects, but this is not established in humans. We aimed to examine the relation between tea intake and cognitive impairment and decline. Among community-living Chinese adults aged > or = 55 y in the Singapore Longitudinal Ageing Studies cohort, we measured tea consumption at baseline and administered the Mini-Mental State Examination (MMSE) at baseline and 1-2 y later. Cognitive impairment was defined as an MMSE score < or = 23 and cognitive decline as a drop in MMSE score of > or = 1 point. We performed cross-sectional analysis of baseline data from 2501 participants and longitudinal analysis of data from 1438 cognitively intact participants. Odds ratios (ORs) of association were calculated in logistic regression models that adjusted for potential confounders. Total tea intake was significantly associated with a lower prevalence of cognitive impairment, independent of other risk factors. Compared with the ORs for rare or no tea intake, the ORs for low, medium, and high levels of tea intake were 0.56 (95% CI: 0.40, 0.78), 0.45 (95% CI: 0.27, 0.72), and 0.37 (95% CI: 0.14, 0.98), respectively (P for trend < 0.001). For cognitive decline, the corresponding ORs were 0.74 (95% CI: 0.54, 1.00), 0.78 (95% CI: 0.55, 1.11), and 0.57 (95% CI: 0.32, 1.03), respectively (P for trend = 0.042). These effects were most evident for black (fermented) and oolong (semi-fermented) teas, the predominant types consumed by this population. In contrast, no association between coffee intake and cognitive status was found. Regular tea consumption was associated with lower risks of cognitive impairment and decline.
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The Mini-Mental State Examination was modified for use in a non-western elderly population and named the Korean Version of the Mini-Mental State Examination (MMSE-K). Study subjects were a group of normal subjects and a group of patients with functional mental disorders. Among the variables of age, sex, residence, education and diagnosis, education was the only factor found to influence total MMSE-K scores. Among the component parts of the MMSE-K, orientation in time, orientation in place, concentration/calculation and language function were significantly influenced by education. After adding one point to scores of orientation in time, two to scores of concentration/calculation and one to scores of language function in non-educated individuals, differences between total scores and scores of the three items corrected lost statistical significance between the educated and non-educated elderly groups. Cutoff points for cognitive impairment and their diagnostic validity are not presented in this article.
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Forty patients diagnosed as suffering from senile dementia of the Alzheimer type received either 80 mg Ginkgo biloba special extract (GBE)* or matching placebo t.i.d. for three months in a randomized, double blind study of the efficacy and tolerance of GBE. The patients were assessed using a test battery at baseline and at 1, 2 and 3 months. The test battery included the SKT (a brief test of cognitive function, memory and attention), the Sandoz Clinical Assessment Geriatric Scale, choice reaction time, saccadic eye movements and EEG. Memory and attention, as measured by the SKT, improved significantly in the active treatment group after one month, as did psychopathology, psychomotor performance, functional dynamics and neurophysiology as measured by the above tests. The drug was well tolerated and no adverse drug reactions were recorded during the trial.
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The occurrence of frontal midline theta activity (4-7 Hz) was studied in a simulated driving task during consecutive phases of goal-directed behaviour. Electrical activity of the forebrain (Fz) was analysed in a simulated traffic situation in which the subject had to find the correct way to drive a car through a set of roads in a computer game. The occurrence of theta activity was analysed during seven consecutive sections of the game. The results showed that the occurrence of theta activity increased during learning--successful behaviour produced more theta than unsuccessful behaviour. In some sections of the game the percentage of theta was larger than in others. It is suggested that the theta activity reflects relaxed concentration after mastering the game.
Article
Some elderly individuals exhibit significant memory deficits but do not have dementia because their general intellect is preserved and they have no impairments in everyday activities. These symptoms are often a precursor to Alzheimer disease (AD), but sometimes dementia does not occur, even after many years of observation. There is currently no reliable way to distinguish between these 2 possible outcomes in an individual patient. We hypothesized that clear impairments in at least 1 cognitive domain in addition to memory would help identify those who will progress to AD. To determine whether nondemented patients with impairments in memory and other domains are more likely than those with memory impairment alone to develop AD. In a retrospective study, we evaluated 48 nondemented, nondepressed patients with clinical and psychometric evidence of memory impairment who were followed up for 2 or more years. Age-adjusted normative criteria were used to identify whether additional impairments were present in language, attention, motor visuospatial function, and verbal fluency at this initial evaluation. The presence or absence of dementia after 2 years and at the most recent neurological evaluation was compared in subjects with normal scores in all 4 of these cognitive areas apart from memory (M-) and those with impairment in 1 or more of these areas (M+). Outcomes were adjusted for age, intelligence at initial evaluation, and years of education. Of the 48 nondemented patients with memory loss, 17 met M- criteria, leaving 31 in the M+ group. Deficits in block design were the most frequent abnormality other than memory loss. At the 2-year follow-up, 1 M- subject (6%) had progressed to AD, whereas 15 (48%) of the M+ group had progressed to AD (P =.003). At the most recent follow-up (mean +/- SD, 4.0 +/- 2.0 years), 4 (24%) of the M- patients progressed to AD compared with 24 (77%) of the M+ patients (P<.001). Among nondemented elderly patients, memory loss alone rarely progresses to dementia in the subsequent 2 years. However, the risk of dementia is significantly increased among patients with clear cognitive impairments beyond memory loss. Further study is needed to determine whether patients with impairments limited to memory loss have a distinctive clinical course or pathophysiology.
Article
Recent theoretical work has suggested that brain oscillations in the theta band are involved in active maintenance and recall of working memory representations. To test this theoretical framework we recorded neuromagnetic responses from 10 subjects performing the Sternberg task. Subjects were required to retain a list of 1, 3, 5 or 7 visually presented digits during a 3-s retention period. During the retention period we observed ongoing frontal theta activity in the 7-8.5-Hz band recorded by sensors over frontal brain areas. The activity in the theta band increased parametrically with the number of items retained in working memory. A time-frequency analysis revealed that the task-dependent theta was present during the retention period and during memory scanning. Following the memory task the theta activity was reduced. These results suggest that theta oscillations generated in frontal brain regions play an active role in memory maintenance.
Article
To estimate the age-specific incidence rate of mild cognitive impairment (MCI) according to sex and educational level and to explore the course of MCI, particularly its progression to AD, in a population-based cohort. A community-based cohort of nondemented elderly people (Personnes Agées QUID [PAQUID]) was followed longitudinally for 5 years. MCI was defined as memory complaints with objective memory impairment, without dementia, impairment of general cognitive functioning, or disability in activities of daily living. Incidence rates were calculated using the person-years method. A descriptive analysis at the different follow-up times was performed to study the course of MCI. At baseline, there were 58 prevalent cases of MCI (2.8% of the sample). During a 5-year follow-up, 40 incident cases of MCI occurred in 1,265 subjects at risk. The global incidence rate of MCI was 9.9/1,000 person-years. MCI was a good predictor of AD with an annual conversion rate of 8.3% and a good specificity, but it was very unstable over time: Within 2 to 3 years, only 6% of the subjects continued to have MCI, whereas >40% reverted to normal. Conventionally defined MCI has reasonable predictive value and specificity for AD. However, MCI was very unstable across time in this study. Furthermore, the definition of MCI seems to be too restrictive and should probably be extended to other categories of individuals also at high risk of developing AD.
Article
The primary target of licensed drugs for the treatment of Alzheimer's disease is the inhibition of the enzyme acetylcholinesterase, although preventing beta-amyloidosis is a prime target for drugs in development. The in vitro dual anti-cholinesterase and beta-secretase activities of Camellia sinensis L. extract (tea) is reported. Green and black tea inhibited human acetylcholinesterase (AChE) with IC(50) values of 0.03 mg/mL and 0.06 mg/mL respectively, and human butyrylcholinesterase (BuChE) with IC(50) values 0.05 mg/mL. Green tea at a final assay concentration of 0.03 mg/mL inhibited beta-secretase by 38%. These novel findings suggest that tea infusions contain biologically active principles, perhaps acting synergistically, that may be used to retard the progression of the disease assuming that these principles, yet to be identified, reach the brain.
Article
The risk of developing dementia by elderly patients with only subjective memory complaints (SMC) is unclear. Our objective was to assess the prognosis of such patients regarding subsequent development of dementia. From 1992 to 1996, 211 consecutive patients (age 67.4 +/- 9.4 years, mean +/- SD) were diagnosed as having SMC. These patients were followed for 3 years or to the time they were diagnosed with dementia, whichever came first. A survival analysis was performed for occurrence of dementia within 3 years. The duration of memory decline was shorter among patients who developed dementia than among those who did not (32.6 vs. 49.9 months, F = 3.3, p = 0.07). Patients who developed dementia tended to be older at the reported onset of memory decline (71 vs. 66.2 years, F = 3.2, p = 0.07). Lower risk of dementia was associated with higher cognitive performance at entry [odds ratio (OR) = 0.74 (0.59-0.92)] and longer time from onset of memory decline to referral [OR = 0.91 (0.85-0.98)]. Subjects with SMC have an increased risk of developing dementia, particularly those with lower cognitive status at entry and with older age at onset of memory complaints, and shorter duration of their memory complaints.
Article
Beta-amyloid peptide (Abeta) is considered responsible for the pathogenesis of Alzheimer's disease (AD). Several lines of evidence support that Abeta-induced cytotoxicity is mediated through the generation of reactive oxygen species (ROS). Thus, agents that scavenge ROS level may usefully impede the development or progress of AD. Green tea extract has been known to have such antioxidant properties. Our previous studies demonstrate that green tea extract protected ischemia/reperfusion-induced brain cell death by scavenging oxidative damages of macromolecules. In this study, we investigated the effects of green tea extract on Abeta-induced oxidative cell death in cultured rat pheochromocytoma (PC12) cells. PC12 cells treated with Abeta25-35 (10-50 microM) showed intracellular ROS elevation, the formation of 8-oxodG (an oxidized form of DNA), and underwent apoptotic cell death in a dose-dependent manner. Abeta(25-35) treatment upregulated pro-apoptotic p53 at the gene level, and Bax and caspase-3 at the protein level, but downregulated anti-apoptotic Bcl-2 protein. Interestingly, co-treated green tea extract (10-50 microg/ml) dose-dependently attenuated Abeta(25-35) (50 microM)-induced cell death, intracellular ROS levels, and 8-oxodG formation, in addition to p53, Bax, and caspase-3 expression, but upregulated Bcl-2. Furthermore, green tea extract prevented the Abeta(25-35)-induced activations of the NF-kappaB and ERK and p38 MAP kinase pathways. Our study suggests that green tea extract may usefully prevent or retard the development and progression of AD.
Article
Studies of memory retrieval have identified electroencephalographic (EEG) correlates of a test item's old-new status, reaction time, and memory load. In the current study, we used a multivariate analysis to disentangle the effects of these correlated variables. During retrieval, power of left-parietal theta (4-8 Hz) oscillations increased in proportion to how well a test item was remembered, and theta in central regions correlated with decision making. We also studied how these oscillatory dynamics complemented event-related potentials. These findings are the first to demonstrate that distinct patterns of theta oscillations can simultaneously relate to different aspects of behavior.
Article
L-Theanine is an amino acid contained in green tea leaves which is known to block the binding of L-glutamic acid to glutamate receptors in the brain. Because the characteristics of L-Theanine suggest that it may influence psychological and physiological states under stress, the present study examined these possible effects in a laboratory setting using a mental arithmetic task as an acute stressor. Twelve participants underwent four separate trials: one in which they took L-Theanine at the start of an experimental procedure, one in which they took L-Theanine midway, and two control trials in which they either took a placebo or nothing. The experimental sessions were performed by double-blind, and the order of them was counterbalanced. The results showed that L-Theanine intake resulted in a reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition. Moreover, analyses of heart rate variability indicated that the reductions in HR and s-IgA were likely attributable to an attenuation of sympathetic nervous activation. Thus, it was suggested that the oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.
Article
Functional food products should provide scientifically proven beneficial effects in healthy subjects. The highly sensitive method of EEG recording from healthy human volunteers was used in a randomized, placebo controlled crossover study to investigate the effects of a change in physiological parameters after ingestion of a total of 750 ml of a softdrink containing 0.232 g of ginseng and 2 g of ginkgo extract, both produced by water extraction. Application of a random, placebo controlled crossover design was done with 10 healthy male volunteers. EEG recordings were performed 1, 2, 3 and 4 h under the conditions of 10 min eyes open, 5 min eyes closed and 5 min reading short stories. Auditory P300 potentials were recorded every hour in addition to the EEG recordings. Source density analysis of the data revealed an attenuation of circadian induced electrical delta power decreases under the condition of eyes open and closed recording from centro-parieto-occipital electrode positions. During a reading test even absolute increases of delta power were observed at these electrode sites. These changes were statistically significant at p < 2% for the second hour (eyes open and reading) and are interpreted to indicate a higher degree of emotional well-being. Decreases in latency (from 333.9 to 321.3 ms) as well as increases of amplitude (from 2.07 to 3.95 microV) of the auditory P300 potential at the electrode position Pz point to a possible improvement of attention, however, the difference did not reach statistical significance.
Article
Subjective memory complaint (SMC) in normal individuals may predict future cognitive decline. The goal of this study was to examine whether the probability of decline increases with growing intensity of complaint. Normal subjects over the age of 50 years were included in a longitudinal retrospective study (mean follow-up time = 8 years). All subjects (n = 230) underwent cognitive and medical examination at baseline. The presence of SMC was determined based on Global Deterioration Scale staging. A subgroup of 83 participants also received baseline assessment for the intensity of SMC. Logistic regression was used to predict outcome from baseline variables. Three outcome groups were established at the final visit: nondeclining, declining and diagnostically unstable (i.e. the diagnosis changed over time: from normal to mild cognitive impairment, then back to normal). The presence of SMC was a predictor of future decline but also increased the likelihood of the unstable diagnosis. Increasing intensity of SMC did not further raise the risk for decline. High intensity of complaints and more pronounced affective symptoms predicted the unstable clinical diagnosis. The presence of SMC contributes to the risk of future decline, however, the increasing intensity of the perceived impairment does not further enhance the risk.
Article
Source density analysis of EEG recordings from 12 healthy human volunteers was used in a randomized, placebo controlled cross over study to investigate the change in physiological parameters after ingestion of a soft drink containing green tea extract enriched with L-theanine and theogallin. EEG was recorded 1, 2, 3 and 4 h after ingestion during different recording conditions. Visually evoked P300 potentials were recorded every hour in addition to the EEG recordings. Analysis of the data revealed a general attenuation of electrical delta power under the condition of eyes open during the first hour (statistically significant at p < 0.01). During a reading test increases of delta and theta power were observed at frontal electrode sites starting with the second hour after administration, significant at the third and fourth hour (p < 0.04) in comparison to placebo. These changes indicate a higher level of mental performance. Increases of beta 1 power starting with the second hour indicated a higher degree of relaxation. However, no statistical significance was reached. Analysis of visually evoked P300 waves revealed a decrease in latency at the last hour (statistical significance p < 0.04) as well as increases of amplitudes at the electrode position Cz (from the first to the third hour, statistically not significant). This type of result in general suggests an improvement of attention. Thus, decaffeinated extract of green tea still has a stimulating effect despite the lack of caffeine presumably due to its high content in L-theanine and theogallin as found in preclinical experiments.
Article
To study the effects of green tea extract administration on age-related cognition in young and old male Wistar rats. Young and old rats were orally administered 0.5% green tea extract for a period of eight weeks and were evaluated by passive avoidance, elevated maze plus paradigm and changes in acetylcholinesterase activity. Treatment of young and old rats with the extract resulted in no significant difference in performance on the rota rod treadmill test/righting reflex time. Green tea extract significantly improved learning and memory in older rats, with increased retention latency to enter difference in passive avoidance test. In the elevated maze test, green tea treatment resulted in significantly more number of entries in the enclosed arm by the young and old rats. Decline in acetylcholinesterase activity was observed in the cerebrum of green tea treated old rats in comparison to the green tea treated young rats. Green tea extract administration is effective in enhancing learning and memory in aged rats, and hence, may serve useful in reversing age-related deficits.
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Im-provement of memory impairment by l-theanine through inhi-bition of acetylcholinesterase activi