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ABSTRACT: This study aimed to examine the acute and sub-chronic effects of cocoa polyphenols on cognition and mood. In a randomized, double-blind study, healthy middle-aged participants received a dark chocolate drink mix standardized to contain 500 mg, 250 mg or 0 mg of polyphenols (placebo) in a parallel-groups design. Participants consumed their assigned treatment once daily for 30 days. Cognition was measured with the Cognitive Drug Research system and self-rated mood with the Bond-Lader Visual Analogue Scale. Participants were tested at baseline, at 1, 2.5 and 4 h after a single acute dose and again after receiving 30 days of treatment. In total, 72 participants completed the trial. After 30 days, the high dose of treatment significantly increased self-rated calmness and contentedness relative to placebo. Mood was unchanged by treatment acutely while cognition was unaffected by treatment at all time points. This randomized controlled trial is perhaps the first to demonstrate the positive effects of cocoa polyphenols on mood in healthy participants. This provides a rationale for exploring whether cocoa polyphenols can ameliorate the symptoms associated with clinical anxiety or depression.
Journal of Psychopharmacology 01/2013; · 3.04 Impact Factor
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ABSTRACT: BACKGROUND: Multivitamins are the most commonly used supplement in the developed world. Recent epidemiologic findings suggest that multivitamin use increases the risk of mortality. OBJECTIVE: We aimed to determine whether multivitamin-multimineral treatment, used for primary or secondary prevention, increases the risk of mortality in independently living adults.Methods: We performed a meta-analysis of randomized controlled trials. Multiple electronic databases were systematically searched from March to October 2012. Randomized controlled primary or secondary prevention trials were considered for inclusion. Eligible trials investigated daily multivitamin-multimineral supplementation for ≥1 y. Cohorts described as institutionalized or as having terminal illness (tertiary prevention) were excluded. The number of deaths and the sample size of each study arm were extracted independently by 2 researchers. Twenty-one articles were included in the analysis, which generated a total pooled sample of 91,074 people and 8794 deaths. These trials were pooled in a meta-analysis, and the outcomes were expressed as RRs and 95% CIs. RESULTS: The average age of the pooled sample was 62 y, and the average duration of supplementation was 43 mo. Across all studies, no effect of multivitamin-multimineral treatment on all-cause mortality (RR: 0.98; 95% CI: 0.94, 1.02) was observed. There was a trend for a reduced risk of all-cause mortality across primary prevention trials (RR: 0.94; 95% CI: 0.89, 1.00). Multivitamin-multimineral treatment had no effect on mortality due to vascular causes (RR: 1.01; 95% CI: 0.93, 1.09) or cancer (RR: 0.96; 95% CI: 0.88, 1.04). No statistical evidence of heterogeneity or publication bias was observed. CONCLUSION: Multivitamin-multimineral treatment has no effect on mortality risk.
American Journal of Clinical Nutrition 12/2012; · 6.67 Impact Factor
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ABSTRACT: BACKGROUND: While many randomised controlled trials have been conducted on multivitamins, to our knowledge no qualitative research exploring the subjective experience of taking a multivitamin during a clinical trial has been reported. METHODS: Semi-structured and open-ended written questions were incorporated into a 16-week double-blind, randomised, placebo-controlled, parallel groups trial of once-daily multivitamin administration. At the final study visit (week 16), three open-ended questions were posed to elucidate any positive, negative or unusual experiences from taking either the multivitamin or matched placebo. Qualitative thematic analysis was undertaken by researchers who were blind as to treatment condition of participants, and triangulation (independent analysis from three researchers) was employed to ensure methodological rigour. Participant's experiences were categorised as "positive" or "negative" and a Chi Square analysis was then applied to each of the experiential themes, to compare experiences between the multivitamin and placebo groups, (subdividing the groups by gender). Usual experiences were categorised and discussed separately. RESULTS: Of the 182 participants enrolled, 116 completed the study and qualitative data were available from 114 participants. Thematic analysis revealed significant effects in favour of the multivitamin over placebo for participants experiencing increased energy levels (p=.022) and enhanced mood (p=.027). The beneficial effect on energy levels was particularly evident among female participants. A trend was found for participants reporting better sleep in the multivitamin over placebo. The multivitamin and placebo groups did not significantly differ in perceived positive or negative effects in areas relating to other aspects of mental function or physical health. No significant negative effects were revealed, although there was a non-significant trend for more people in the multivitamin group having minor digestive complaints. CONCLUSION: This represents the first documented qualitative investigation of participants' experience of chronic administration of a multivitamin. Results uncovered a range of subjective beneficial effects that are consistent with quantitative data from previously published randomised controlled trials examining the effects of multivitamins and B vitamin complexes on mood and well-being.Trial registration: Prior to commencement this trial was registered with the Australian New Zealand Clinical Trials Registry (www.anzctr.org.au) ACTRN12611000092998.
Nutrition Journal 12/2012; 11(1):110. · 2.48 Impact Factor
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ABSTRACT: OBJECTIVE: Growing evidence suggests that dietary supplementation with selected micronutrients and nutraceuticals may have the potential to improve cognition in older adults. Fewer studies have investigated the effects of these substances on brain activity. METHODS: This study was a randomised, double-blind, placebo-controlled trial, conducted to explore the effects of 16weeks supplementation with a combined multivitamin, mineral and herbal formula on the steady state visually evoked potential (SSVEP) measure of brain electrical activity. Participants were elderly women aged between 64 and 79years, with subjective memory complaints. Baseline and post-treatment SSVEP data was obtained for 22 participants in the multivitamin group and 19 in the placebo group. A spatial working memory delayed response task (DRT) was performed during the recording of the SSVEP. RESULTS: The results revealed that when compared to placebo, multivitamin supplementation delayed SSVEP latency during retrieval, interpreted as an increase in inhibitory neural processes. Behavioural performance on the DRT was not improved by the multivitamin, however improved performance accuracy was associated with increased midline central SSVEP latency. There were no multivitamin-related effects on SSVEP amplitude. CONCLUSION: These findings indicate that in the elderly, multivitamin supplementation may enhance neural efficiency during memory retrieval.
Physiology & Behavior 08/2012; 107(3):346-354. · 2.87 Impact Factor
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ABSTRACT: Cardiovascular disease risk predicts cognitive decline although the mechanisms underpinning this association remain unclear. Increasing cardiovascular risk may impair cerebral blood flow predisposing to cerebrovascular damage, cognitive decline, and dementia.
This study examined the association between the Framingham General Cardiovascular Risk Profile and cerebral blood flow velocity in 160 healthy middle-aged adults. Blood flow velocity was assessed in both the common carotid and middle cerebral arteries using Doppler.
In adjusted linear regression models, cardiovascular risk predicted higher pulsatile (common carotid artery β=0.56, ΔR(2)=0.19, P<0.001; middle cerebral artery β=0.40, ΔR(2)=0.09, P<0.001) and lower mean flow velocity (common carotid artery β=-0.49, ΔR(2)=0.14, P<0.001; middle cerebral artery β=-0.27, ΔR(2)=0.04, P<0.05). Cardiovascular risk predicted common carotid artery mean and pulsatile flow over and above the effects of age (ΔR(2)=0.11-0.19, P<0.001) and sex (ΔR(2)=0.03-0.03, P<0.05). In contrast, cardiovascular risk remained a significant predictor of middle cerebral artery pulsatile, but not mean flow velocity, when controlling for age (ΔR(2)=0.05, P<0.05) and sex (ΔR(2)=0.06, P<0.01).
Cardiovascular risk has divergent effects on mean and pulsatile blood flow velocity, each of which may independently contribute to cerebral pathology and cognitive impairment.
Stroke 08/2012; 43(10):2803-5. · 5.73 Impact Factor
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ABSTRACT: Nutritional and vitamin status may be related to cognitive function and decline in older adults. The aim of this study was to investigate the effects of nutritional supplementation on cognition in older men.
The current study was an 8-week, placebo-controlled, double-blind investigation into the effects of a multivitamin, mineral and herbal supplement (Swisse Men's Ultivite®, Swisse Vitamins Pty Ltd, Melbourne, Australia) on cognitive performance in older men. Participants were 51 male individuals aged between 50 and 74 years, with a sedentary lifestyle. Cognitive performance was assessed at baseline and post-treatment using a computerised battery of cognitive tasks, enabling the measurement of a range of attentional and memory processes. Blood measures of vitamin B(12) , folate and homocysteine were collected prior to and after supplementation.
The results of this study revealed that contextual recognition memory performance was significantly improved following multivitamin supplementation (p < 0.05). Performance on other cognitive tasks did not change. Levels of vitamin B(12) and folate were significantly increased with a concomitant decrease in homocysteine, indicating that relatively short-term supplementation with a multivitamin can benefit these risk factors for cognitive decline.
Findings from this study indicate that daily multivitamin supplementation may improve episodic memory in older men at risk of cognitive decline.
Human Psychopharmacology Clinical and Experimental 06/2012; 27(4):370-7. · 2.48 Impact Factor
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Con K Stough,
Matthew P Pase,
Vanessa Cropley,
Stephen Myers,
Karen Nolidin,
Rebecca King,
David Camfield,
Keith Wesnes, Andrew Pipingas,
Kevin Croft,
Dennis Chang,
Andrew B Scholey
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ABSTRACT: BACKGROUND: One of the major challenges associated with our ageing population is the increasing incidence of age-associated cognitive decline, which has significant implications for an individual's ability to lead a productive and fulfilling life. In pure economic terms the costs of ageing reflects decreased productivity and engagement with the workforce. The maintenance of brain health underpinning intact cognition is a key factor to maintaining a positive, engaged, and productive lifestyle. In light of this, the role of diet, including supplementation with nutritional and even pharmacological interventions capable of ameliorating the neurocognitive changes that occur with age constitute vital areas of research. METHODS: In order to reduce cognitive ageing, the ARC longevity intervention (ARCLI) was developed to examine the effects of two promising natural pharmacologically active supplements on cognitive performance. ARCLI is a randomized, placebo-controlled, double-blind, 3-arm clinical trial in which 465 participants will be randomized to receive an extract of Bacopa monnieri (CDRI08 300 mg/day), Pycnogenol (150 mg/day), or placebo daily for 12 months. Participants will be tested at baseline and then at 3, 6 and 12 months post-randomization on a wide battery of cognitive, neuropsychological and mood measures, cardiovascular (brachial and aortic systolic and diastolic blood pressures as well as arterial stiffness), biochemical (assays to measure inflammation, oxidative stress and safety) as well as genetic assessments (telomere length and several Single Nucleotide Polymorphisms). The primary aim is to investigate the effects of these supplements on cognitive performance. The secondary aims are to explore the time-course of cognitive enhancement as well as potential cardiovascular and biochemical mechanisms underpinning cognitive enhancement over the 12 months of administration.ARCLI will represent one of the largest and most comprehensive experimental clinical trials in which supplements are administered to elderly participants. Results from ARCLI may help develop novel preventative health practices and nutritional/pharmacological targets in the elderly for cognitive and brain health. TRIAL REGISTRATION: Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12611000487910.
Nutrition Journal 03/2012; 11:11. · 2.48 Impact Factor
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ABSTRACT: There is potential for multivitamin supplementation to improve cognition in the elderly. This randomized, double-blind, placebo-controlled trial was conducted to investigate the effects of 16 weeks multivitamin supplementation (Swisse Women's 50+ Ultivite ®) on cognition in elderly women.
Participants in this study were 56 community dwelling, elderly women, with subjective complaints of memory loss. Cognition was assessed using a computerized battery of memory and attention tasks designed to be sensitive to age-related declines to fluid intelligence, and a measure of verbal recall. Biochemical measures of selected nutrients, homocysteine, markers of inflammation, oxidative stress, and blood safety parameters were also collected. All cognitive and haematological parameters were assessed at baseline and 16 weeks post-treatment.
The multivitamin improved speed of response on a measure of spatial working memory, however benefits to other cognitive processes were not observed. Multivitamin supplementation decreased levels of homocysteine and increased levels of vitamin B(6) and B(12), with a trend for vitamin E to increase. There were no hepatotoxic effects of the multivitamin formula indicating this supplement was safe for everyday usage in the elderly.
Sixteen weeks ssupplementation with a combined multivitamin, mineral and herbal formula may benefit working memory in elderly women at risk of cognitive decline.
Psychopharmacology 03/2012; 220(2):351-65. · 4.08 Impact Factor
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ABSTRACT: Complementary medicine use is becoming increasingly popular with multivitamins being the most commonly used vitamin supplement. Although adequate vitamin and nutrient concentrations are necessary for optimal health and cognitive functioning, there is no scientific consensus as to whether multivitamin use prevents cognitive decline or improves mental functioning. The aim of the present study was to determine if multivitamins can be used efficaciously to improve cognitive abilities. A systematic review of randomized controlled trials was performed. Meta-analysis was performed on those cognitive tests used across the largest number of studies. Multiple electronic databases were searched until July 2011 by two authors. Randomized, placebo-controlled trials were considered appropriate if they reported on the chronic effects (≥1 month) of oral multivitamin supplementation on any valid cognitive outcomes. Ten trials were included in review (n = 3,200). Meta-analysis indicated that multivitamins were effective in improving immediate free recall memory (SMD = 0.32; 95% CI: 0.09-0.56, p < 0.01) but not delayed free recall memory (SMD = -0.14; 95% CI: -0.43-0.14, p = 0.33) or verbal fluency (SMD = 0.06; 95% CI: -0.05-0.18, p = 0.26). There was no evidence of publication bias or heterogeneity. Other cognitive abilities sensitive to AD pathology, such as executive and visuospatial functions, were found to be under researched. In conclusion, multivitamins were found to enhance immediate free recall memory but no other cognitive domains.
Journal of Alzheimer's disease: JAD 02/2012; 29(3):561-9. · 3.74 Impact Factor
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ABSTRACT: Although arterial stiffness has recently been confirmed as a predictor of cardiovascular disease, the association between arterial stiffness and cognitive decline is less clear.
We performed a systematic review and meta-analysis to examine the evidence for large artery stiffness as a cause of cognitive decline and dementia.
Electronic databases were systematically searched until September 2011 for studies reporting on the longitudinal relationship between any validated measure of large artery stiffness and cognitive decline or dementia. Meta-analysis was performed on four studies investigating the association between aortic pulse wave velocity and a decline in Mini-Mental State Examination scores.
Six relevant longitudinal studies were located, conducted over an average of 5 years follow up. Arterial stiffness was predictive of cognitive decline in five/six studies. In meta-analysis, higher aortic stiffness predicted lower Mini-Mental State Examination scores within the sample (β=-0.03, 95% confidence interval (CI): -0.06 to 0.01, n= 3947), although studies were not all homogeneous, and statistical heterogeneity was present (I(2) = 71.9%, P= 0.01). Removal of one study with a relatively younger cohort and lower median aortic stiffness found higher aortic stiffness to significantly predict cognitive decline (β=-0.04, 95% CI: -0.07 to -0.01, n= 3687) without evidence of heterogeneity (I(2) = 9.5%, P= 0.33). There was little research investigating the effects of aortic stiffness on the development of dementia.
Aortic stiffness was found to predict cognitive decline in both qualitative review and quantitative analysis.
Internal Medicine Journal 12/2011; 42(7):808-15. · 1.54 Impact Factor
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Andrew Scholey,
Luke A Downey,
Joseph Ciorciari, Andrew Pipingas,
Karen Nolidin,
Melissa Finn,
Melissa Wines,
Sarah Catchlove,
Alirra Terrens,
Emma Barlow,
Leanne Gordon,
Con Stough
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ABSTRACT: Green tea is reported to have wide ranging beneficial health outcomes across epidemiological studies, which have been attributed to its flavonoid content. We investigated whether the flavonoid epigallocatechin gallate (EGCG) modulates brain activity and self-reported mood in a double-blind, placebo controlled crossover study. Participants completed baseline assessments of cognitive and cardiovascular functioning, mood and a resting state electroencephalogram (EEG) before and then 120 min following administration of 300 mg EGCG or matched placebo. EGCG administration was associated with a significant overall increase in alpha, beta and theta activity, also reflected in overall EEG activity, more dominant in midline frontal and central regions, specifically in the frontal gyrus and medial frontal gyrus. In comparison to placebo the EGCG treatment also increased self-rated calmness and reduced self rated stress. This pattern of results suggests that participants in the EGCG condition may have been in a more relaxed and attentive state after consuming EGCG. This is in keeping with the widespread consumption of green tea for its purported relaxing/refreshing properties. The modulation of brain function due to EGCG is deserving of further controlled human studies.
Appetite 11/2011; 58(2):767-70. · 2.59 Impact Factor
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ABSTRACT: There is a demonstrated association between poor mood and deficiency in several micronutrients. Multivitamin supplements contain a wide range of nutrients, suggesting that they may be effective in improving mood; however, few studies have investigated this potential in randomized, controlled trials. This study investigates the effects of a multivitamin, mineral, and herbal supplement on mood and stress in a group of healthy, older male volunteers.
In this randomized, double-blind, placebo-controlled trial, fifty men, aged 50-69 years, supplemented for a period of 8 weeks with a multivitamin formulation that contained vitamins (at levels above recommended daily intakes), minerals, antioxidants, and herbal extracts, or a placebo. They completed a series of mood and stress questionnaires at baseline and post-supplementation.
Compared with placebo, there was a significant reduction in the overall score on a depression anxiety and stress scale and an improvement in alertness and general daily functioning in the multivitamin group.
Supplementation with a multivitamin, mineral and herbal formulation may be useful in improving alertness and reducing negative mood symptoms and may also improve feelings of general day-to-day well-being.
Human Psychopharmacology Clinical and Experimental 11/2011; 26(8):560-7. · 2.48 Impact Factor
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ABSTRACT: Age-related cognitive decline (ARCD) and dementia are of increasing concern to an ageing population. In recent years, there has been considerable research focused on effective dietary interventions that may prevent or ameliorate ARCD and dementia. While a number of studies have considered the impact that dairy products may have on physiological health, particularly with regard to the metabolic syndrome and cardiovascular health, further research is currently needed in order to establish the impact that dairy products have in the promotion of healthy brain function during ageing. The present review considers the available evidence for the positive effects of dairy products on the metabolic syndrome and glucose regulation, with consideration of the implications for neurocognitive health. A literature search of current (September 2010) meta-analyses/reviews and original research regarding dairy products and cognition was conducted through SCOPUS using the following search terms for dairy consituents: dairy, milk, cheese, yoghurt, probiotics, whey protein, alpha lactalbumin, calcium, B-12, bioactive peptides and colostrinin (CLN). These search terms for dairy products were combined with the following search terms related to cognition and health: cognition, cognitive decline, dementia, Alzheimer's disease, metabolic syndrome, diabetes, insulin resistance and glucose regulation. Concerns regarding SFA and other fatty acids found in dairy products are also reviewed in relation to different forms of dairy products. The review also considers recent evidence for positive neurocognitive effects associated with bioactive peptides, CLN and proline-rich polypeptides, α-lactalbumin, vitamin B12, calcium and probiotics. Future directions for the extraction and purification of beneficial constituents are also discussed. It is concluded that low-fat dairy products, when consumed regularly as part of a balanced diet, may have a number of beneficial outcomes for neurocognitive health during ageing.
The British journal of nutrition 02/2011; 106(2):159-74. · 3.45 Impact Factor
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ABSTRACT: While cardiovascular and mood benefits of dietary omega-3 fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are manifest, direct neurophysiological evidence of their effects on cortical activity is still limited. Hence we chose to examine the effects of two proprietary fish oil products with different EPA:DHA ratios (EPA-rich, high EPA:DHA; DHA-rich) on mental processing speed and visual evoked brain activity. We proposed that nonlinear multifocal visual evoked potentials (mfVEP) would be sensitive to any alteration of the neural function induced by omega-3 fatty acid supplementation, because the higher order kernel responses directly measure the degree of recovery of the neural system as a function of time following stimulation. Twenty-two healthy participants aged 18-34, with no known neurological or psychiatric disorder and not currently taking any nutritional supplementation, were recruited. A double-blind, crossover design was utilized, including a 30-day washout period, between two 30-day supplementation periods of the EPA-rich and DHA-rich diets (with order of diet randomized). Psychophysical choice reaction times and multi-focal nonlinear visual evoked potential (VEP) testing were performed at baseline (No Diet), and after each supplementation period. Following the EPA-rich supplementation, for stimulation at high luminance contrast, a significant reduction in the amplitude of the first slice of the second order VEP kernel response, previously related to activation in the magnocellular pathway, was observed. The correlations between the amplitude changes of short latency second and first order components were significantly different for the two supplementations. Significantly faster choice reaction times were observed psychophysically (compared with baseline performance) under the EPA-rich (but not DHA-rich) supplementation, while simple reaction times were not affected. The reduced nonlinearities observed under the EPA-rich diet suggest a mechanism involving more efficient neural recovery of magnocellular-like visual responses following cortical activation.
PLoS ONE 01/2011; 6(12):e28214. · 4.09 Impact Factor
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ABSTRACT: Over the last decade, Asian ginseng (Panax ginseng) has been shown to improve aspects of human cognitive function. American ginseng (Panax quinquefolius) has a distinct ginsenoside profile from P. ginseng, promising cognitive enhancing properties in preclinical studies and benefits processes linked to human cognition.
The availability of a highly standardised extract of P. quinquefolius (Cereboost™) led us to evaluate its neurocognitive properties in humans for the first time.
This randomised, double-blind, placebo-controlled, crossover trial (N = 32, healthy young adults) assessed the acute mood, neurocognitive and glycaemic effects of three doses (100, 200 400 mg) of Cereboost™ (P. quinquefolius standardised to 10.65% ginsenosides). Participants' mood, cognitive function and blood glucose were measured 1, 3 and 6 h following administration.
There was a significant improvement of working memory (WM) performance associated with P. quinquefolius. Corsi block performance was improved by all doses at all testing times. There were differential effects of all doses on other WM tasks which were maintained across the testing day. Choice reaction time accuracy and 'calmness' were significantly improved by 100 mg. There were no changes in blood glucose levels.
This preliminary study has identified robust working memory enhancement following administration of American ginseng. These effects are distinct from those of Asian ginseng and suggest that psychopharmacological properties depend critically on ginsenoside profiles. These results have ramifications for the psychopharmacology of herbal extracts and merit further study using different dosing regimens and in populations where cognition is fragile.
Psychopharmacology 10/2010; 212(3):345-56. · 4.08 Impact Factor
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ABSTRACT: Whilst pulse pressure and pulse wave velocity have been shown to predict cognitive outcomes, the relationship between arterial stiffness and cognition has not yet been explored in an entirely healthy nonclinical population. Furthermore, the effects of arterial stiffness on cognition are yet to be examined with computerized cognitive test batteries sensitive to subtle differences in cognitive performance. The aim of the present study was to examine the relationship between arterial stiffness (pulse pressure and augmentation index) and specific domains of cognitive performance in a healthy middle-aged sample. INDIVIDUALS AND METHOD: The sample comprised 92 healthy individuals, aged between 40 and 65 years, with no history of cardiovascular disease, diabetes, stroke, hypertension, smoking and were free from medication. The cognitive drug research (CDR) computerized system was implemented to assess domains of cognitive performance, whereas pulse pressure and augmentation index were determined centrally by a noninvasive SphygmoCor device.
Pulse pressure was an independent predictor of both episodic secondary memory performance (beta = -0.27, R change = 0.07, P < 0.05) and speed of memory retrieval (beta = 0.24, R change = 0.06, P < 0.05). Augmentation index was also an independent predictor of speed of memory (beta = 0.27, R change = 0.07, P < 0.01). Working memory, power of attention and continuity of attention were not predicted by pulse pressure or augmentation index.
It was concluded that healthy middle-aged adults are vulnerable to memory deficits as a result of normal increases in pulse pressure associated with ageing.
Journal of hypertension 08/2010; 28(8):1724-9. · 4.02 Impact Factor
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ABSTRACT: The present study investigated the behavioral and neuropsychological characteristics of decision-making behavior during a gambling task as well as how these characteristics may relate to the Somatic Marker Hypothesis and the Frequency of Gain model. The applicability to intertemporal choice was also discussed. Patterns of card selection during a computerized interpretation of the Iowa Gambling Task were assessed for 10 men and 10 women. Steady State Topography was employed to assess cortical processing throughout this task. Results supported the hypothesis that patterns of card selection were in line with both theories. As hypothesized, these 2 patterns of card selection were also associated with distinct patterns of cortical activity, suggesting that intertemporal choice may involve the recruitment of right dorsolateral prefrontal cortex for somatic labeling, left fusiform gyrus for object representations, and the left dorso-lateral prefrontal cortex for an analysis of the associated frequency of gain or loss. It is suggested that processes contributing to intertemporal choice may include inhibition of negatively valenced options, guiding decisions away from those options, as well as computations favoring frequently rewarded options. Intertemporal choice refers to a type of deci-sion making that involves a trade-off between costs and benefits occurring over time (Kable & Glimcher, 2007). Understanding the neuropsy-chological mechanisms that influence such de-cision making may facilitate favorable business and economic choices as well as assist the pre-diction of consumer behavior. Several decision-making theories have now emerged that may provide insight into the neuropsychological mechanisms influencing intertemporal choice. This study focuses on two such theories that are referred to herein as the Somatic Marker Hy-pothesis (SMH) and Frequency-of-Gain (FOG) model. Both these theories may provide an av-enue for the assessment of neural activity in regards to quantifiable decision-making efforts. The SMH, proposed by Damasio and col-leagues, suggests that decisions are dependant upon the influence of somatic markers, or rep-resentations of them, which flag potential op-tions with an emotional valence. Negative so-matic markers are thought to guide decisions away from the associated option and toward favorable outcomes (Bechara & Damasio, 2005; Damasio, 1994). Lesion studies have implicated the ventromedial prefrontal cortex as a crucial part of the neural circuitry that links stored somatic information with thoughts or memories internally generated in working memory (Be-chara, Damasio, Damasio, & Anderson, 1994; Bechara, Damasio, Damasio, & Lee, 1999). Neuroimaging studies have also implicated the dorsolateral prefrontal cortex (DLPFC) in this decision-making process; however, its precise contribution is still the subject of some debate (Bechara & Damasio, 2005; Bechara, Damasio, Tranel, & Anderson, 1998; Knoch et al., 2006; Manes et al., 2002). The debate centers on whether results from neuroimaging studies in-volving the IGT have been adequately inter-preted in light of the cognitive penetrability of the reward/punishment schedule inherent in the IGT and the relative lack of direct causal
Journal of Neuroscience, Psychology and Economics,. 01/2010;
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ABSTRACT: Old age is generally accompanied by a decline in memory performance. Specifically, neuroimaging and electrophysiological studies have revealed that there are age-related changes in the neural correlates of episodic and working memory. This study investigated age-associated changes in the steady state visually evoked potential (SSVEP) amplitude and latency associated with memory performance. Participants were 15 older (59-67 years) and 14 younger (20-30 years) adults who performed an object working memory (OWM) task and a contextual recognition memory (CRM) task, whilst the SSVEP was recorded from 64 electrode sites. Retention of a single object in the low demand OWM task was characterised by smaller frontal SSVEP amplitude and latency differences in older adults than in younger adults, indicative of an age-associated reduction in neural processes. Recognition of visual images in the more difficult CRM task was accompanied by larger, more sustained SSVEP amplitude and latency decreases over temporal parietal regions in older adults. In contrast, the more transient, frontally mediated pattern of activity demonstrated by younger adults suggests that younger and older adults utilize different neural resources to perform recognition judgements. The results provide support for compensatory processes in the aging brain; at lower task demands, older adults demonstrate reduced neural activity, whereas at greater task demands neural activity is increased.
Brain and Cognition 02/2009; 69(3):571-9. · 3.17 Impact Factor
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ABSTRACT: Dietary interventions may have the potential to counter age-related cognitive decline. Studies have demonstrated an improvement in age-related cognitive impairment in animals after supplementation with plant extracts containing flavonoids but there are few human studies. This double-blind, controlled study examined the effects on cognitive performance of a 5 week supplementation with Enzogenol Pinus radiata bark extract containing flavonoids, in 42 males aged 50-65 years, with a body mass index >25. Participants were supplemented for 5 weeks either with Enzogenol plus vitamin C, or with vitamin C only. A battery of computerized cognitive tests was administered, and cardiovascular and haematological parameters were assessed prior to and following supplementation. The speed of response for the spatial working memory and immediate recognition tasks improved after supplementation with Enzogenol plus vitamin C, whereas vitamin C alone showed no improvements. A trend in a reduction of systolic blood pressure was observed with Enzogenol plus vitamin C, but not with vitamin C alone. The blood safety parameters were unchanged. The findings suggest a beneficial effect of supplementation with Enzogenol on cognition in older individuals. Larger studies are needed to ascertain its potential as a preventive treatment for age-related cognitive decline.
Phytotherapy Research 10/2008; 22(9):1168-74. · 2.09 Impact Factor
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ABSTRACT: Schizophrenia is associated with impairments of attentional control on classic experimental paradigms such as the Stroop task. However, at a basic level the neurochemical mechanisms that may be responsible for such impairments are poorly understood. In this study, we sought to investigate the influence of brain monoamine function on Stroop task performance in healthy participants using the established methods of acute dietary serotonin, dopamine, and combined monoamine depletion. The study was a double-blind placebo controlled design in which 12 healthy male participants completed the Stroop task under four acute treatment conditions: (a) balanced/placebo control, (b) acute tryptophan depletion, (c) acute tyrosine/phenylalanine depletion, and (d) acute tyrosine/phenylalanine/tryptophan depletion (combined monoamine depletion). Decreased Stroop interference indicating improved attentional control was observed after both tryptophan depletion and tyrosine/phenylalanine depletion, while there was no significant change in interference after combined monoamine depletion. Findings suggest that reduced tonic dopamine or serotonin activity within specific neural circuits (such as the striatum, anterior cingulate, or prefrontal cortex) may play a critical role in attentional control, possibly by improving gating of information via reducing noise in monoaminergic systems. These findings enhance our understanding of the neurochemical basis of attentional control and the possible cause of attentional control deficits in schizophrenia.
Neuropsychopharmacology 08/2007; 32(7):1600-10. · 7.99 Impact Factor
