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Dorsolateral Prefrontal Cortex N-Acetylaspartate/Total Creatine (NAA/tCr) Loss in Male Recreational Cannabis Users
Abstract
Cannabinoids present neurotoxic and neuroprotective properties in in vitro studies, inconsistent alterations in human neuroimaging studies, neuropsychological deficits, and an increased risk for psychotic episodes.
Proton magnetic resonance spectroscopy ((1)H-MRS), neuropsychological testing, and hair analysis for cannabinoids was performed in 13 male nontreatment-seeking recreational cannabis users and 13 male control subjects.
A significantly diminished N-acetylaspartate/total creatine (NAA/tCr) ratio in the dorsolateral prefrontal cortex (DLPFC) was observed in cannabis users (p = .0003). The NAA/tCr in the putamen/globus pallidum region correlated significantly with cannabidiol (R(2) = .66, p = .004). Results of the Wisconsin Card Sorting test, Trail making Test, and D2 test for attention were influenced by cannabinoids.
Chronic recreational cannabis use is associated with an indication of diminished neuronal and axonal integrity in the DLPFC in this study. As chronic cannabis use is a risk factor for psychosis, these results are interesting because diminished NAA/tCr ratios in the DLPFC and neuropsychological deficits were also reported in schizophrenia. The strong positive correlation of NAA/tCr and cannabidiol in the putamen/globus pallidum is in line with neuroprotective properties of cannabidiol, which were also observed in in vitro model studies of Parkinson's disease.
... A positive correlation was found between ethanol intake and GSK3β expression. Ethanol consumption leads to GSK3β overexpression, which makes the brain more sensitive to the anxiety effects of ethanol abstinence, resulting in increased ethanol self-administration [194]. It is known that during repeated cycles of excessive alcohol administration and withdrawal, the activity of Akt and PI3K signaling in the NAcc is increased [181], and phosphorylation at Ser9 residue of GSK3β is increased [195]. ...
... By inducing the translation of synaptic proteins, mTOR enables neuroadaptations resulting from excessive alcohol intake. Induction of mTOR activity is enabled by inhibition of GSK3β, confirming its important role in ethanol dependence [194]. ...
Glycogen synthase kinase-3β (GSK3β), primarily described as a regulator of glycogen metabolism, is a molecular hub linking numerous signaling pathways and regulates many cellular processes like cytoskeletal rearrangement, cell migration, apoptosis, and proliferation. In neurons, the kinase is engaged in molecular events related to the strengthening and weakening of synapses, which is a subcellular manifestation of neuroplasticity. Dysregulation of GSK3β activity has been reported in many neuropsychiatric conditions, like schizophrenia, major depressive disorder, bipolar disorder, and Alzheimer’s disease. In this review, we describe the kinase action in reward circuit-related structures in health and disease. The effect of pharmaceuticals used in the treatment of addiction in the context of GSK3β activity is also discussed.
... After prolonged periods of abstention (28 days), adolescents showed a deficit of "historical" (semantic) memory [Medina et al., 2007], though visuospatial memory remained unimpaired [Medina et al., 2007;Schweinsburg et al., 2010]. Defi cit of this type of memory was seen in adult cannabis consumers abstaining for some period of time [Hermann et al., 2007;McHale and Hunt, 2008], though other studies found associative memory and semantic memory to be intact [Chang et al., 2006;Wadsworth et al., 2006;Fisk and Montgomery, 2008]. ...
... In contrast, other authors found that selective and divided attention remained intact in adolescents after 45 days of abstinence [Jacobson et al., 2004]. Adult marijuana consumers abstaining for periods from several hours to a week demonstrated impaired attention and concentration [Wadsworth et al., 2006;Hermann et al., 2007]; however, other studies reported the absence of any such impairments [Chang et al., 2006;Grant et al., 2011]. ...
Cannabinoids are natural compounds found in the hemp (Cannabis sativa). Scientific interest in cannabinoids arose after the discovery of the major psychoactive component in hemp, Δ9-tetrahydrocannabinol. Subsequent studies detected receptors in the brain subject to the actions of this compound, along with ligands for these receptors, i.e., endogenous cannabinoids (EC), which make up, along with the enzymes synthesizing, transporting, and degrading them, the endocannabinoid system (ECS). Interest in EC has consistently increased in recent years, especially after their important role in cognitive functions was discovered. They are regulators of synaptic transmission in the brain, mediate numerous forms of plasticity, and control neuron energy metabolism. EC exert influences using a series of mechanisms and interactions with neuromediators, neurotrophic factors, and neuropeptides. The main functions of EC in the brain are retrograde synaptic signaling and neuromodulation, which maintain cellular homeostasis. Information on the influences of cannabinoid drugs on cognitive functions is very contradictory. The cause of this may be that there are still inadequate strictly scientific data from clinical and sociological studies, while in animal experiments different authors use different methods and approaches for actions on the ECS. Thus, effects can differ depending on the substances used, their doses, and routes of administration, and the tasks and experimental conditions selected for testing. There is an extensive literature on the protective effect of ECS activation in neurodegenerative diseases in humans and models of cognitive deficit in animals. This review addresses data providing evidence of the influences of cannabinoid drugs and activation of the EC system on cognitive functions in the normal brain and in neurodegenerative diseases, Alzheimer’s disease, and temporal epilepsy. The possible causes of contradictions in existing data are also discussed.
... Some studies of chronic cannabis use have found significant impairments in memory function of young (Fried et al. 2005) and older adults (Wadsworth et al. 2006;Lovell et al. 2018), as well as learning in young (Becker et al. 2014;Gonzalez et al. 2012) and older adults (Lovell et al. 2018). Furthermore, cognitive impairments have also been found in the domains of attention/ concentration in adults ages 18-55 (Solowij et al. 2002;Hermann et al. 2007;Cousijn et al. 2013;Field 2005;Bolla et al. 2002). Conversely, other studies have reported no significant differences between users and nonusers in young adults (Grant et al. 2012;Ramaekers et al. 2009), middleaged adults (Pope Jr et al. 2001Harding et al. 2012), and older adults (Lovell et al. 2018) on a broad range of cognitive functions. ...
... One cognitive process that has garnered major interest in this literature is attention processing. Several studies have suggested that attention function may be impaired in regular adult cannabis users (Hart et al. 2011;Wadsworth et al. 2006;Solowij et al. 2002;Hermann et al. 2007;Chang et al. 2006). Specifically, studies have shown that adult chronic regular users exhibit impairments on measures of divided attention (Bosker et al. 2013), sustained attention (Hunault et al. 2009), visual information processing (Wadsworth et al. 2006), and selective attention (Solowij et al. 1995). ...
Rationale and objectives
Cognitive processing impairments have been associated with acute cannabis use, but there is mixed evidence regarding the cognitive effects of chronic cannabis use. Several neuroimaging studies have noted selective-attention processing differences in those who chronically use cannabis, but the neural dynamics governing the altered processing is unclear.
Methods
Twenty-four adults reporting at least weekly cannabis use in the past 6 months on the Cannabis Use Disorder Identification Test – Revised were compared to 24 demographically matched controls who reported no prior cannabis use. All participants completed a visual selective attention processing task while undergoing magnetoencephalography. Time-frequency windows of interest were identified using a data-driven method, and spectrally specific neural activity was imaged using a beamforming approach.
Results
All participants performed within normal range on the cognitive task. Regular cannabis users displayed an aberrant cognitive interference effect in the theta (4–8 Hz) frequency range shortly after stimulus onset (i.e., 0–250 ms) in the right occipital cortex. Cannabis users also exhibited altered functional connectivity between the right prefrontal cortex and right occipital cortices in comparison to controls.
Conclusions
Individuals with a history of regular cannabis use exhibited abnormal theta interference activity in the occipital cortices, as well as altered prefrontal-occipital functional connectivity in the theta range during a visual selective attention task. Such differences may reflect compensatory processing, as these participants performed within normal range on the task. Understanding the neural dynamics in chronic, regular cannabis users may provide insight on how long-term and/or frequent use may affect neural networks underlying cognitive processes.
... Proton spectroscopy studies dealing with cannabis consumption that have been published so far have focused on regions such as the frontal lobe, basal ganglia, hippocampus, and temporal lobe. Reduced NAA is the most frequently observed finding in cannabis users [59][60][61][62]. Particularly in the youngest subjects, reduced NAA levels were detected in frontal lobe regions, including the dorsolateral prefrontal cortex, anterior cingulate gyrus, inferior frontal gyrus, and midfrontal gray matter. ...
Purpose
This prospective cross-sectional study investigated the influence of regular cannabis use on brain metabolism in young cannabis users by using combined proton and phosphorus magnetic resonance spectroscopy.
Methods
The study was performed in 45 young cannabis users aged 18–30, who had been using cannabis on a regular basis over a period of at least 2 years and in 47 age-matched controls. We acquired 31P MRS data in different brain regions at 3T with a double-resonant 1H/31P head coil, anatomic images, and 1H MRS data with a standard 20-channel 1H head coil. Absolute concentration values of proton metabolites were obtained via calibration from tissue water as an internal reference, whereas a standard solution of 75 mmol/l KH2PO4 was used as an external reference for the calibration of phosphorus signals.
Results
We found an overall but not statistically significant lower concentration level of several proton and phosphorus metabolites in cannabis users compared to non-users. In particular, energy-related phosphates such as adenosine triphosphate (ATP) and inorganic phosphate (Pi) were reduced in all regions under investigation. Phosphocreatine (PCr) showed lowered values mainly in the left basal ganglia and the left frontal white matter.
Conclusion
The results suggest that the increased risk of functional brain disorders observed in long-term cannabis users could be caused by an impairment of the energy metabolism of the brain, but this needs to be verified in future studies.
... Chronic exposure to Δ-9-THC or marijuana extracts persistently alters the structure and function of the rat hippocampus [127], a brain region involved with learning and memory processes. In humans, brain imaging studies evidenced that chronic cannabis use alters neuronal and axonal integrity in the dorsolateral prefrontal cortex [128]. Recent studies have shown that chronic cannabis consumption can disrupt neuronal and axonal integrity, as measured by N-acetyl aspartate magnetic resonance spectroscopy in the dorsolateral prefrontal cortex [129] and is linked to a decreased volume in selected brain areas such as the parahippocampal gyrus and parietal lobe [130]. ...
Background:
Cannabis is the most widely used illicit substance. Numerous scientific evidence confirm the strong association between cannabis and psychosis. Exposure to cannabis can induce the development of psychosis and schizophrenia in vulnerable individuals. However, the neurobiological processes underlying this relationship are unknown. Neurotrophins are a class of proteins that serve as survival factors for central nervous system (CNS) neurons. In particular, nerve growth factor (NGF) plays an important role in the survival and function of cholinergic neurons while brain-derived neurotrophic factor (BDNF) is involved in synaptic plasticity and the maintenance of midbrain dopaminergic and cholinergic neurons. Glial Cell Derived Neurotrophic Factor (GDNF) promotes the survival of midbrain dopaminergic neurons and Neuregulin 1 (NrG-1) contributes to glutamatergic signals regulating the N-methyl-D-aspartate (NMDA). They have a remarkable influence on the neurons involved in the Δ-9-THC (tethra-hydro-cannabinol) action, such as dopaminergic and glutamatergic neurons, and can play dual roles: first, in neuronal survival and death, and, second, in activity-dependent plasticity.
Methods:
In this brief update, reviewing in a narrative way the relevant literature, we will focus on the effects of cannabis on this class of proteins, which may be implicated, at least in part, in the mechanism of the psychostimulant-induced neurotoxicity and psychosis.
Conclusion:
Since altered levels of neurotrophins may participate in the pathogenesis of psychotic disorders which are common in drug users, one possible hypothesis is that repeated cannabis exposure can cause psychosis by interfering with neurotrophins synthesis and utilization by CNS neurons.
... Reduced NAA/tCr ratios have been reported in diverse cases, such as patients with Alzheimer's disease, euthymic bipolar disorder, or men with recreational cannabis usage [70][71][72]. Interestingly, increased NAA/tCr levels have rarely been reported. ...
To diagnose autism spectrum disorder (ASD), researchers have sought biomarkers whose alterations correlate with the susceptibility to ASD. However, biomarkers closely related to the pathophysiology of ASD are lacking. Even though excitation/inhibition (E/I) imbalance has been suggested as an underlying mechanism of ASD, few studies have investigated the actual ratio of glutamate (Glu) to γ-aminobutyric acid (GABA) concentration in vivo. Moreover, there are controversies in the directions of E/I ratio alterations even in extensively studied ASD animal models. Here, using proton magnetic resonance spectroscopy ( ¹ H-MRS) at 9.4T, we found significant differences in the levels of different metabolites or their ratios in the prefrontal cortex and hippocampus of Cntnap2 −/− mice compared to their wild-type littermates. The Glu/GABA ratio, N-acetylaspartate (NAA)/total creatine (tCr) ratio, and tCr level in the prefrontal cortex were significantly different in Cntnap2 −/− mice compared to those in wild-type mice, and they significantly correlated with the sociability of mice. Moreover, receiver operating characteristic (ROC) analyses indicated high specificity and selectivity of these metabolites in discriminating genotypes. These results suggest that the lowered Glu/GABA ratio in the prefrontal cortex along with the changes in the other metabolites might contribute to the social behavior deficit in Cntnap2 −/− mice. Our results also demonstrate the utility of ¹ H-MRS in investigating the underlying mechanisms or the diagnosis of ASD.
... Prolonged use of Cannabis is related to the decrease of neuronal and axonal integrity in the DLPFC. The results is interesting as the decreased ratio of NAA/tCr in DLPFC and neuropsychological deficits were also reported in schizophrenia (Hermann et al. 2007), breathing-related to CNS as the opioid analgesics have the possibility of combining with other CNS depressants like benzodiazepines which creates problems (Zutler and Holty 2011). There are also reports showing the suppression of apnoea by CBD. ...
Sickle cell anemia (SCA) is an inherited disorder in the β-globin chain of hemoglobin that affects millions of people around the world, especially children. This disease prevalently occurs in some Mediterranean and Saharan Africa. For the treatment of SCA patients, a wide range of drugs have been explored by targeting antisickling activity, γ-globulin induction, antiplatelet effect, etc., but hardly a few drugs have shown potential to combat with this complex disease phenomenon. In spite of unprecedented advances in modern system of medicine, people in the disease-prone area have been taking traditional medicinal plants or plant-derived products to increase the life span of patients. Moreover, numerous clinical trials have been going on for the use of natural products under the purview of symptomatic management of SCA. This chapter is focused on the effect of natural products in pure form or characterized phytoconstituents on particularly inhibition of hemoglobin polymerization. This summarized information will be beneficial for further exploration of new therapeutics in the treatment arena of SCA.
... Prolonged use of Cannabis is related to the decrease of neuronal and axonal integrity in the DLPFC. The results is interesting as the decreased ratio of NAA/tCr in DLPFC and neuropsychological deficits were also reported in schizophrenia (Hermann et al. 2007), breathing-related to CNS as the opioid analgesics have the possibility of combining with other CNS depressants like benzodiazepines which creates problems (Zutler and Holty 2011). There are also reports showing the suppression of apnoea by CBD. ...
The impact of cannabis use on neurological soft signs (NSS) in patients with schizophrenia is a topic of growing interest. This narrative review aims to provide an overview of the current understanding of this relationship. The PubMed database was used to identify relevant articles, and the initial search yielded a total of 144 publications. By using automation tools, 137 records were removed, and seven remaining studies were further reviewed in full-text. Results. The findings suggest that, although the use of cannabis decreases the global expression of NSS, heavy cannabis use is associated with higher levels of NSS in sensorimotor subdomains related to complex motor tasks. Furthermore, neuroimaging studies have revealed alterations in brain regions involved in sensorimotor execution and control in individuals with heavy cannabis use. These findings support the hypothesis that cannabis, through its effects on the sensorimotor system, can impair neurological functioning and increase the positive symptoms of schizophrenia. In conclusion, this narrative review highlights the complex relationship between cannabis use, neurological soft signs and schizophrenia. Understanding the impact of cannabis on NSS in patients with schizophrenia is crucial for developing targeted interventions and for optimizing treatment outcomes. Further research, including longitudinal studies and meta-analyses, is warranted to enhance our understanding of this important area.
Parkinson’s disease is a slowly progressive, degenerative disorder characterized by resting tremors, stiffness (rigidity), slow and decreased movement (bradykinesia), and eventually, gait and postural instability. Treatment aims to restore dopaminergic functions in the brain with levodopa/carbidopa and other drugs, e.g., dopamine agonists, monoamine oxidase type B [MAO-B] inhibitors, and amantadine. For refractory, disabling symptoms in patients without dementia, stereotactic deep brain stimulation or lesional surgery, levodopa, and an apomorphine pump may help.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
An informative and comprehensive review from the leading researchers in the field, this book provides a complete one-stop guide to neuroimaging techniques and their application to a wide range of neuropsychiatric disorders. For each disorder or group of disorders, separate chapters review the most up-to-date findings from structural imaging, functional imaging and/or molecular imaging. Each section ends with an overview from a internationally-renowned luminary in the field, addressing the question of 'What do we know and where are we going?' Richly illustrated throughout, each chapter includes a 'summary box', providing readers with explicit take-home messages. This is an essential resource for clinicians, researchers and trainees who want to learn how neuroimaging tools lead to new discoveries about brain and behaviour associations in neuropsychiatric disorders.
Aim
There is increasing concern that cannabinoid exposure during adolescence may disturb brain maturation and produce long-term cognitive deficits. However, studies in human subjects have provided limited evidence for such causality. The present study utilized behavioral and neuroimaging endpoints in female non-human primates to examine the effects of acute and chronic exposure during adolescence to the cannabinoid receptor full agonist, AM2389, on cognitive processing and brain function and chemistry.
Materials and methods
Adolescent female rhesus macaques were trained on a titrating-delay matching-to-sample (TDMTS) touchscreen task that assays working memory. TDMTS performance was assessed before and during chronic exposure to AM2389, following antagonist (rimonabant) administration, and after discontinuation of the chronic regimen. Resting-state fMRI connectivity and magnetic resonance spectroscopy data were acquired prior to drug treatment, during chronic exposure, and following its discontinuation. Voxels were placed in the medial orbitofrontal cortex (mOFC), a region involved in memory processing that undergoes maturation during adolescence.
Results
TDMTS performance was dose-dependently disrupted by acute AM2389; however, chronic treatment resulted in tolerance to these effects. TDMTS performance also was disrupted by discontinuation of the chronic regimen but surprisingly, not by rimonabant administration during chronic AM2389 treatment. mOFC N- acetylaspartate/creatine ratio decreased after acute and chronic administration but returned to baseline values following discontinuation of chronic treatment. Finally, intra-network functional connectivity (mOFC) increased during the chronic regimen and returned to baseline values following its discontinuation.
Conclusion
Neural effects of a cannabinergic drug may persist during chronic exposure, notwithstanding the development of tolerance to behavioral effects. However, such effects dissipate upon discontinuation, reflecting the restorative capacity of affected brain processes.
Many American and Dutch adolescents use marijuana regularly. There is concern that such use may impair cognitive function more in adolescents than adults. We examined effects of regular marijuana use on long-term memory and perseveration among American and Dutch adolescents. We administered Buschke's Selective Reminding Test (BSRT) to assess long-term memory and the Wisconsin Card Sorting Test (WCST) to assess perseveration in male teenagers. Usable test data were obtained for 12 American marijuana users, 13 American controls, 9 Dutch marijuana users, and 12 Dutch controls. In BSRT, users showed lower overall long-term storage than controls (adjusted means ± SE's for numbers of words per trial of 9.4 ± 0.2, 13.4 ± 0.3, 11.7 ± 0.2, and 12.4 ± 0.2 for American users, Dutch users, American controls, and Dutch controls, respectively). Marijuana was associated with memory effects only in American, not Dutch, users. Bivariate Pearson correlations for American and Dutch users combined showed associations of lower total recall with more uses in the previous year and lifetime (r = –0.61 and r = –0.53, respectively); and more perseverative errors with more uses in the previous year (r = 0.55). Some findings were consistent with the possibility that regular adolescent marijuana use causes deficits in cognition, especially memory. However, a causal interpretation cannot be inferred from our findings and is challenging to reconcile with the observation of memory deficits only in American users. Our study was novel in examining the influence of nationality on marijuana's cognitive effects. More studies of this topic should compare effects across nationalities or cultures.
The phytocannabinoids of Cannabis sativa L. have, since ancient times, been proposed as a pharmacological alternative for treating various central nervous system (CNS) disorders. Interestingly, cannabinoid receptors (CBRs) are highly expressed in the basal ganglia (BG) circuit of both animals and humans. The BG are subcortical structures that regulate the initiation, execution, and orientation of movement. CBRs regulate dopaminergic transmission in the nigro-striatal pathway and, thus, the BG circuit also. The functioning of the BG is affected in pathologies related to movement disorders, especially those occurring in Parkinson’s disease (PD), which produces motor and non-motor symptoms that involving GABAergic, glutamatergic, and dopaminergic neural networks. To date, the most effective medication for PD is levodopa (l-DOPA); however, long-term levodopa treatment causes a type of long-term dyskinesias, l-DOPA-induced dyskinesias (LIDs). With neuromodulation offering a novel treatment strategy for PD patients, research has focused on the endocannabinoid system (ECS), as it participates in the physiological neuromodulation of the BG in order to control movement. CBRs have been shown to inhibit neurotransmitter release, while endocannabinoids (eCBs) play a key role in the synaptic regulation of the BG. In the past decade, cannabidiol (CBD), a non-psychotropic phytocannabinoid, has been shown to have compensatory effects both on the ECS and as a neuromodulator and neuroprotector in models such as 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and reserpine, as well as other PD models. Although the CBD-induced neuroprotection observed in animal models of PD has been attributed to the activation of the CB1 receptor, recent research conducted at a molecular level has proposed that CBD is capable of activating other receptors, such as CB2 and the TRPV-1 receptor, both of which are expressed in the dopaminergic neurons of the nigro-striatal pathway. These findings open new lines of scientific inquiry into the effects of CBD at the level of neural communication. Cannabidiol activates the PPARγ, GPR55, GPR3, GPR6, GPR12, and GPR18 receptors, causing a variety of biochemical, molecular, and behavioral effects due to the broad range of receptors it activates in the CNS. Given the low number of pharmacological treatment alternatives for PD currently available, the search for molecules with the therapeutic potential to improve neuronal communication is crucial. Therefore, the investigation of CBD and the mechanisms involved in its function is required in order to ascertain whether receptor activation could be a treatment alternative for both PD and LID.
Electroconvulsive therapy (ECT) is still the most effective treatment not only for psychotic depression, but also for treatment of resistant or other severe forms of major depressive episodes. Nevertheless, the exact nature of the therapeutic effect of ECT is unknown. Modern theories of depression suggest changes of synaptic plasticity especially within the hippocampus. It was hypothesized that such changes may be reflected in changes of proton magnetic resonance spectroscopy (1 H MRS) detectable signals. The current literature on 1 H MRS studies on ECT effects is small with a large diversity of MRS methods applied, brain regions studied and metabolite changes found. Nevertheless, there is good evidence that changes in neurometabolite concentrations are induced by ECT that can be non invasively monitored by 1 H MRS. There also are pioneering 1 H MRS studies on animal models of depression: the Learned Helplessness model in rats and the chronic social stress model in tree shrews. The proposed review will summarize the current MRS findings in humans and animals and discuss possible interpretations.
A review and critique of the literature pertaining to the use of cognitive remediation techniques in patients with schizophrenia is presented. The review is organized into three sections, according to the neuropsychological deficit targeted for remediation: 1) executive-function, 2) attention, and 3) memory. With regards to executive-function, despite an initial report suggesting that Wisconsin Card Sorting Test performance cannot be remediated, subsequent studies suggest that performance can be improved on a variety of dependent measures including perseverative errors, categories achieved, and conceptual level responses. These observations were confirmed by a meta-analytic investigation that revealed large mean effects sizes (d
+ = 0.96) for these studies. Effect sizes were homogenous across discrepant remediation strategies and dependent measures. With regards to attention, serial scanning can be improved with instruction and reinforcement, whereas there is mixed evidence suggesting that practice-based attention drills can improve performance on measures of sustained attention in schizophrenia. With regards to memory, relatively simple semantic and affective elaborate encoding strategies elevates verbal list-learning memory in patients with schizophrenia to levels consistent with controls. A similar encoding procedure, combined with vigilance training, produces substantial improvement in social cue recognition. Avenues for future research are discussed.
Cognitive correlates of long-term cannabis use have been elusive. We tested the hypothesis that long-term cannabis use is associated with deficits in short term memory, working memory, and attention in a literate, westernized culture (Costa Rica) in which the effects of cannabis use can be isolated.
Two cohorts of long-term cannabis users and nonusers were studied. Within each cohort, users and nonusers were comparable in age and socioeconomic status. Polydrug users and users who tested positive for the use of cannabis at the time of cognitive assessment after a 72-hour abstention period were excluded. The older cohort (whose age was approximately 45 years) had consumed cannabis for an average of 34 years, and comprised 17 users and 30 nonusers, who had been recruited in San José, Costa Rica, and had been observed since 1973. The younger cohort (whose age was approximately 28 years) had consumed cannabis for an average of 8 years, and comprised 37 users and 49 nonusers. Short-term memory, working memory, and attentional skills were measured in each subject.
Older long-term users performed worse than older nonusers on 2 short-term memory tests involving learning lists of words. In addition, older long-term users performed worse than older nonusers on selective and divided attention tasks associated with working memory. No notable differences were apparent between younger users and nonusers.
Long-term cannabis use was associated with disruption of short-term memory, working memory, and attentional skills in older long-term cannabis users.
To determine which proton magnetic resonance (MR) spectroscopic imaging measures are best for lateralizing the seizure focus in patients who have temporal lobe epilepsy with and in those without hippocampal atrophy on MR images, the extent of contralateral abnormalities, and whether there is a correlation between MR spectroscopic imaging findings and surgical outcome.
MR spectroscopic imaging was performed in 16 adult patients with temporal lobe epilepsy and unilateral electroencephalographic findings and in 16 adult control subjects. Eleven patients underwent surgery; all patients underwent MR imaging.
Nine patients had hippocampal atrophy on MR images. An ipsilateral decrease in the N-acetylaspartate concentration or the ratio of N-acetylaspartate to the sum of creatine and choline (N-acetylaspartate/ [creatine + choline]) was found in all patients. Decreased contralateral N-acetylaspartate concentration, N-acetylaspartate/(creatine + choline), or N-acetylaspartate concentration and N-acetylaspartate/(creatine + choline) were detected in eight patients (50%), which suggests bilateral abnormalities not detected with MR imaging. In the five patients who underwent surgery and did not show hippocampal atrophy on MR images, successful and unsuccessful outcomes were correctly predicted with N-acetylaspartate concentration.
Decreased N-acetylaspartate concentration is not due solely to hippocampal atrophy. Contralateral abnormalities are much more frequent than expected. MR spectroscopic imaging is valuable in the presurgical evaluation of epilepsy.
Marijuana consumption elicits diverse physiological and psychological effects in humans, including memory loss. Here we report that Delta9-tetrahydrocannabinol (THC), the major psychoactive component of marijuana, is toxic for hippocampal neurons. Treatment of cultured neurons or hippocampal slices with THC caused shrinkage of neuronal cell bodies and nuclei as well as genomic DNA strand breaks, hallmarks of neuronal apoptosis. Neuron death induced by THC was inhibited by nonsteroidal anti-inflammatory drugs, including indomethacin and aspirin, as well as vitamin E and other antioxidants. Furthermore, treatment of neurons with THC stimulated a significant increase in the release of arachidonic acid. We hypothesize that THC neurotoxicity is attributable to activation of the prostanoid synthesis pathway and generation of free radicals by cyclooxygenase. These data suggest that some of the memory deficits caused by cannabinoids may be caused by THC neurotoxicity.
The neuroprotective actions of cannabidiol and other cannabinoids were examined in rat cortical neuron cultures exposed to toxic levels of the excitatory neurotransmitter glutamate. Glutamate toxicity was reduced by both cannabidiol, a nonpsychoactive constituent of marijuana, and the psychotropic cannabinoid (-)Delta9-tetrahydrocannabinol (THC). Cannabinoids protected equally well against neurotoxicity mediated by N-methyl-D-aspartate receptors, 2-amino-3-(4-butyl-3-hydroxyisoxazol-5-yl)propionic acid receptors, or kainate receptors. N-methyl-D-aspartate receptor-induced toxicity has been shown to be calcium dependent; this study demonstrates that 2-amino-3-(4-butyl-3-hydroxyisoxazol-5-yl)propionic acid/kainate receptor-type neurotoxicity is also calcium-dependent, partly mediated by voltage sensitive calcium channels. The neuroprotection observed with cannabidiol and THC was unaffected by cannabinoid receptor antagonist, indicating it to be cannabinoid receptor independent. Previous studies have shown that glutamate toxicity may be prevented by antioxidants. Cannabidiol, THC and several synthetic cannabinoids all were demonstrated to be antioxidants by cyclic voltametry. Cannabidiol and THC also were shown to prevent hydroperoxide-induced oxidative damage as well as or better than other antioxidants in a chemical (Fenton reaction) system and neuronal cultures. Cannabidiol was more protective against glutamate neurotoxicity than either ascorbate or alpha-tocopherol, indicating it to be a potent antioxidant. These data also suggest that the naturally occurring, nonpsychotropic cannabinoid, cannabidiol, may be a potentially useful therapeutic agent for the treatment of oxidative neurological disorders such as cerebral ischemia.
Marijuana and related drugs (cannabinoids) have been proposed as treatments for a widening spectrum of medical disorders. R(+)-[2, 3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1, 4-benzoxazin-yl]-(1-naphthalenyl)methanone mesylate (R(+)-WIN 55212-2), a synthetic cannabinoid agonist, decreased hippocampal neuronal loss after transient global cerebral ischemia and reduced infarct volume after permanent focal cerebral ischemia induced by middle cerebral artery occlusion in rats. The less active enantiomer S(-)-WIN 55212-3 was ineffective, and the protective effect of R(+)-WIN 55212-2 was blocked by the specific central cannabinoid (CB1) cannabinoid receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide-hydrochloride. R(+)-WIN 55212-2 also protected cultured cerebral cortical neurons from in vitro hypoxia and glucose deprivation, but in contrast to the receptor-mediated neuroprotection observed in vivo, this in vitro effect was not stereoselective and was insensitive to CB1 and CB2 receptor antagonists. Cannabinoids may have therapeutic potential in disorders resulting from cerebral ischemia, including stroke, and may protect neurons from injury through a variety of mechanisms.
Certain cognitive, behavioral, and emotional deficits (so-called negative symptoms) in patients with schizophrenia have often been attributed to prefrontal cortical pathology, but direct evidence for a relationship between prefrontal neuronal pathology and negative symptoms has been lacking. The authors hypothesized that an in vivo measure of prefrontal neuronal pathology (N:-acetylaspartate [NAA] levels) in patients with schizophrenia would predict negative symptoms.
Proton magnetic resonance spectroscopic imaging ((1)H-MRSI) and rating scales for negative and positive symptoms were used to study 36 patients with schizophrenia. Magnetic resonance spectra were analyzed as metabolite ratios, and parametric correlations were performed.
A regionally selective negative correlation was found between prefrontal NAA-creatine ratio and negative symptom ratings in this group of patients with schizophrenia.
Lower prefrontal NAA-and by inference greater neuronal pathology-predicted more severe negative symptoms in patients with schizophrenia. These data demonstrate a relationship between an intraneuronal measure of dorsolateral prefrontal cortex integrity and negative symptoms in vivo and represent further evidence for the involvement of the dorsolateral prefrontal cortex in negative symptoms associated with schizophrenia.
Using proton magnetic resonance spectroscopic imaging, the authors measured thalamic N-acetylaspartate (NAA) concentrations in patients with schizophrenia.
The study included 15 schizophrenic patients on a stable medication regimen and 15 age-matched healthy comparison subjects. Concentrations of NAA, creatine plus phosphocreatine, and choline-containing compounds in bilateral thalamic regions were determined.
Previous findings of lower NAA concentration in the left and right mediodorsal region of the thalamus and significant correlations between left and right thalamic NAA measures in patients with schizophrenia were corroborated. Furthermore, the concentrations of choline-containing compounds were significantly lower in the schizophrenic patients. No group differences in creatine plus phosphocreatine were found.
There is strong evidence for neuronal dysfunction or loss in the mediodorsal region of the thalamus in patients with schizophrenia.
Although cannabis is the most widely used illicit drug in the United States, its long-term cognitive effects remain inadequately studied.
We recruited individuals aged 30 to 55 years in 3 groups: (1) 63 current heavy users who had smoked cannabis at least 5000 times in their lives and who were smoking daily at study entry; (2) 45 former heavy users who had also smoked at least 5000 times but fewer than 12 times in the last 3 months; and (3) 72 control subjects who had smoked no more than 50 times in their lives. Subjects underwent a 28-day washout from cannabis use, monitored by observed urine samples. On days 0, 1, 7, and 28, we administered a neuropsychological test battery to assess general intellectual function, abstraction ability, sustained attention, verbal fluency, and ability to learn and recall new verbal and visuospatial information. Test results were analyzed by repeated-measures regression analysis, adjusting for potentially confounding variables.
At days 0, 1, and 7, current heavy users scored significantly below control subjects on recall of word lists, and this deficit was associated with users' urinary 11-nor-9-carboxy-Delta9-tetrahydrocannabinol concentrations at study entry. By day 28, however, there were virtually no significant differences among the groups on any of the test results, and no significant associations between cumulative lifetime cannabis use and test scores.
Some cognitive deficits appear detectable at least 7 days after heavy cannabis use but appear reversible and related to recent cannabis exposure rather than irreversible and related to cumulative lifetime use.
Traumatic brain injury triggers the accumulation of harmful mediators that may lead to secondary damage. Protective mechanisms to attenuate damage are also set in motion. 2-Arachidonoyl glycerol (2-AG) is an endogenous cannabinoid, identified both in the periphery and in the brain, but its physiological roles have been only partially clarified. Here we show that, after injury to the mouse brain, 2-AG may have a neuroprotective role in which the cannabinoid system is involved. After closed head injury (CHI) in mice, the level of endogenous 2-AG was significantly elevated. We administered synthetic 2-AG to mice after CHI and found significant reduction of brain oedema, better clinical recovery, reduced infarct volume and reduced hippocampal cell death compared with controls. When 2-AG was administered together with additional inactive 2-acyl-glycerols that are normally present in the brain, functional recovery was significantly enhanced. The beneficial effect of 2-AG was dose-dependently attenuated by SR-141761A, an antagonist of the CB1 cannabinoid receptor.
In recent years the illicit drug ecstasy (MDMA, 3,4-methylenedioxymethamphetamine) has come into widespread use among young people. Despite clear evidence for the neurotoxic potential of MDMA in animals, corresponding evidence in humans is limited to indirect findings. In an exploratory study we compared the hippocampal H-1-MRSI (magnetic resonance spectroscopic imaging) spectra, of five MDMA users with those of controls with no history of substance abuse. Although H-1-MRSI is, sensitive in detecting alterations in neuronal viability in association with diseases leading to neuronal degeneration, we were not able to demonstrate any differences in hippocampal H-1-MRSI between MDMA users and controls.
Cognitive impairments are associated with long-term cannabis use, but the parameters of use that contribute to impairments and the nature and endurance of cognitive dysfunction remain uncertain.
To examine the effects of duration of cannabis use on specific areas of cognitive functioning among users seeking treatment for cannabis dependence.
Multisite retrospective cross-sectional neuropsychological study conducted in the United States (Seattle, Wash; Farmington, Conn; and Miami, Fla) between 1997 and 2000 among 102 near-daily cannabis users (51 long-term users: mean, 23.9 years of use; 51 shorter-term users: mean, 10.2 years of use) compared with 33 nonuser controls.
Measures from 9 standard neuropsychological tests that assessed attention, memory, and executive functioning, and were administered prior to entry to a treatment program and following a median 17-hour abstinence.
Long-term cannabis users performed significantly less well than shorter-term users and controls on tests of memory and attention. On the Rey Auditory Verbal Learning Test, long-term users recalled significantly fewer words than either shorter-term users (P =.001) or controls (P =.005); there was no difference between shorter-term users and controls. Long-term users showed impaired learning (P =.007), retention (P =.003), and retrieval (P =.002) compared with controls. Both user groups performed poorly on a time estimation task (P<.001 vs controls). Performance measures often correlated significantly with the duration of cannabis use, being worse with increasing years of use, but were unrelated to withdrawal symptoms and persisted after controlling for recent cannabis use and other drug use.
These results confirm that long-term heavy cannabis users show impairments in memory and attention that endure beyond the period of intoxication and worsen with increasing years of regular cannabis use.
Literature data related to the merit of hair as a chronological diary of drug exposure, as examined by segmental analysis, are reviewed with emphases on the mechanisms of drug incorporation, physiology of hair growth, and findings resulting from research effort and routine analytical results. In a single anagen strand, a drug dose may be incorporated, within the hair follicle, to a drug-containing zone of approximately 2-5 mm width, which appears at the skin surface 1-5 days after drug exposure and moves regularly away following the strand's growth rate. This process is disturbed by deposition from sweat, sebum, and in rare cases environmental contamination, as well as by elimination during hair care or chemical treatment. In a hair tuft, the time resolution is seriously deteriorated by the presence of 5-15% (or even more) strands in the resting stage, by variability in the growth rate (up to 40%), and by inexact alignment of the strands. Interindividually, the generally accepted medium growth rate of 1.1 ± 0.2 cm/month is only a very rough approximation. When applying to retrospective elucidation of intoxications and control of illegal or therapeutic drug intake cases, correlations ranging from excellent agreement to enormous deviations have been reported. Satisfactory dose-concentration correlation could not be established in both intra- and interindividual studies. Therefore, the domain of routine hair analysis remains the retrospective qualitative detection of drug exposure. Improved time estimation is possible using anagen hair and careful determination of individual growth rate and its variation at the sites of sampling, careful sample handling, and analysis of sufficient segments.
Copyright © 1998 Central Police University.
Background
We monitored the effect of electroconvulsive therapy (ECT) on the nuclear magnetic resonance–detectable metabolites N-acetylaspartate, creatine and phosphocreatine, and choline-containing compounds in the hippocampus by means of hydrogen 1 magnetic resonance spectroscopic imaging. We hypothesized that if ECT-induced memory deterioration was associated with neuronal loss in the hippocampus, the N-acetylaspartate signal would decrease after ECT and any increased membrane turnover would result in an increase in the signal from choline-containing compounds.Methods
Seventeen patients received complete courses of ECT, during which repeated proton magnetic resonance spectroscopic imaging studies of the hippocampal region were performed. Individual changes during the course of ECT were compared with values obtained in 24 healthy control subjects and 6 patients remitted from major depression without ECT.Results
No changes in the hippocampal N-acetylaspartate signals were detected after ECT. A significant mean increase of 16% of the signal from choline-containing compounds after 5 or more ECT treatments was observed. Despite the mostly unilateral ECT application (14 of 17 patients), the increase in the choline-containing compound signal was observed bilaterally. Lactate or elevated lipid signals were not detected. All patients showed clinical amelioration of depression after ECT.Conclusions
Electroconvulsive therapy is not likely to induce hippocampal atrophy or cell death, which would be reflected by a decrease in the N-acetylaspartate signal. Compared with an age-matched control group, the choline-containing compounds signal in patients with a major depressive episode was significantly lower than normal, before ECT and normalized during ECT.
Context Cognitive impairments are associated with long-term cannabis use, but
the parameters of use that contribute to impairments and the nature and endurance
of cognitive dysfunction remain uncertain.Objective To examine the effects of duration of cannabis use on specific areas
of cognitive functioning among users seeking treatment for cannabis dependence.Design, Setting, and Participants Multisite retrospective cross-sectional neuropsychological study conducted
in the United States (Seattle, Wash; Farmington, Conn; and Miami, Fla) between
1997 and 2000 among 102 near-daily cannabis users (51 long-term users: mean,
23.9 years of use; 51 shorter-term users: mean, 10.2 years of use) compared
with 33 nonuser controls.Main Outcome Measures Measures from 9 standard neuropsychological tests that assessed attention,
memory, and executive functioning, and were administered prior to entry to
a treatment program and following a median 17-hour abstinence.Results Long-term cannabis users performed significantly less well than shorter-term
users and controls on tests of memory and attention. On the Rey Auditory Verbal
Learning Test, long-term users recalled significantly fewer words than either
shorter-term users (P = .001) or controls (P = .005); there was no difference between shorter-term
users and controls. Long-term users showed impaired learning (P = .007), retention (P = .003), and retrieval
(P = .002) compared with controls. Both user groups
performed poorly on a time estimation task (P<.001
vs controls). Performance measures often correlated significantly with the
duration of cannabis use, being worse with increasing years of use, but were
unrelated to withdrawal symptoms and persisted after controlling for recent
cannabis use and other drug use.Conclusions These results confirm that long-term heavy cannabis users show impairments
in memory and attention that endure beyond the period of intoxication and
worsen with increasing years of regular cannabis use.
Volumetric proton magnetic resonance spectroscopic imaging (MRSI) was used to generate brain metabolite maps in 15 young and 19 elderly adult volunteers. All subjects also had structural MR scans, and a model, which took into account the underlying structural composition of the brain contributing to each metabolite voxel, was developed and used to estimate the concentration of the N-acetyl-moiety (NAc), creatine (Cr), and choline (Cho) in gray matter and white matter. NAc concentration (signal intensity per unit volume of brain) was higher in gray than white matter and did not differ between young and old subjects despite significant gray matter volume deficits in the older subjects. To the extent that NAc is an index of neuronal integrity, the available gray matter appears to be intact in these older healthy adults. Cr concentrations were much higher in gray than white matter and significantly higher in the old than young subjects. Cho concentration in gray matter was also significantly higher in old than young subjects. Independent determination of metabolite values rather than use of ratios is essential for characterizing age-related changes in brain MRS metabolites. Magn Reson Med 41:276–284, 1999. Published 1999 Wiley-Liss, Inc.
Four tests previously used to determine the presence of brain injury were considered in terms of their comparative advantages, disadvantages, and rationale. These tests were the Wechsler Mental Abilities Scale (Form B or MAS), Shipley-Hartford Retreat Scale for Intellectual Impairment, Hunt-Minnesota Test for Organic Brain Damage, and Rorschach Test. It is suggested that the Rorschach is the most useful for this purpose. The brain injured group consisted of 44 patients who were known to have sustained cerebral damage. The evidence was derived largely from surgeons' reports. In the instances where these were lacking, positive pneumo-encephalograms and/or neurological findings were available. The source of these injuries ranged from high velocity missiles to auto accidents. In regard to the severity and type of injury the neurologist distributed the 44 cases as follows: 11 severe, 21 moderate, and 12 mild; 9 were considered to have focal lesions, 17 were classed as focal-diffuse and 18 were diffuse. The neurotics and normals do not appear to differ in any respect. Although this was suggested by their means, it was considered best to make this test before the two groups were combined into the control group and used averages have been affected by the presence of a few extremely low or high scores. Four of the brain injured cases during the free association period gave stories that bore little relationship to the one that was read to them. However, they retained enough of the original story to receive some credit. In every instance the confabulation had a central idea or theme and was fairly coherent and cohesive, but in each instance elements of circumstantiality, preservation, and pseudo-profundity were present. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Abstract Both spatial working memory deficit and disorganization symptoms have been considered significant components of schizophrenic impairment involved with the dorsolateral prefrontal cortex. The purpose of the present study was to investigate the relationships among spatial working memory, psychiatric symptoms including disorganization symptoms, and social functioning in schizophrenia. Fifty clinically stable patients with schizophrenia and 34 healthy controls participated in the study. Patients were rated with the Brief Psychiatric Rating Scale and the Rehabilitation Evaluation Hall and Baker. The Advanced Trail Making Test was used to evaluate spatial working memory. Patients demonstrated significantly reduced spatial working memory compared to that of healthy controls. Spatial working memory in patients correlated significantly with social functioning such as self-care skills, community skills and speech disturbance, and with disorganization symptoms. Disorganization symptoms also correlated with these aspects of social functioning. In conclusion it is suggested that both spatial working memory deficit and disorganization symptoms, which are impairments involved with the dorsolateral prefrontal cortex dysfunction, can serve as effective predictors of social functioning.
An automated method for analysis of in vivo proton magnetic resonance (MR) spectra and reconstruction of metabolite distributions from MR spectroscopic imaging (MRSI) data is described. A parametric spectral model using acquisition specific, a priori information is combined with a wavelet-based, nonparametric characterization of baseline signals. For image reconstruction, the initial fit estimates were additionally modified according to a priori spatial constraints. The automated fitting procedure was applied to four different examples of MRS data obtained at 1.5 T and 4.1 T. For analysis of major metabolites at medium TE values, the method was shown to perform reliably even in the presence of large baseline signals and relatively poor signal-to-noise ratios typical of in vivo proton MRSI. identification of additional metabolites was also demonstrated for short TE data. Automated formation of metabolite images will greatly facilitate and expand the clinical applications of MR spectroscopic imaging.
Objective and method:
The acute effects of delta9 tetrahydrocannabinol (THC) on cerebral blood flow (CBF) were studied in human subjects. Regional CBF was measured with 15O-water and Positron Emission Tomography (PET) in 32 volunteers with a history of exposure to marijuana. Scans were performed before and after intravenous (I.V.) infusion of either of two doses of THC or a placebo, given under double blind conditions.
Results:
THC but not placebo increased CBF especially in the frontal regions bilaterally, insula and cingulate gyrus and sub-cortical regions with somewhat greater effects in the right hemisphere. While most regions showed significant change at 60 minutes for the lower dose group, the higher dose group had significant change at 30 and 60 minutes. There was a highly significant change in the anterior/posterior ratio for the two THC groups reflecting minimal change in occipital flow but significant increases in frontal flow. Self ratings of THC intoxication showed significant effects, and regression analysis indicated it correlated most markedly with the right frontal region.
Conclusion:
Behavioral manifestations of marijuana intoxication may be associated with increased functional activity of the brain especially the frontal cortex, insula and cingulate gyrus.
Metabolic changes in the hippocampus formation can be investigated with in vivo magnetic resonance spectroscopy (MRS). Learned helplessness (LH) is a well validated animal model of depression which we established in Sprague–Dawley rats defining some as “learned helpless” (LH) or not “learned helpless” (NLH). Helpless and non-helpless rats received a course of daily administered electroconvulsive shocks (ECS) for 6 days. MRS measurements were performed on a 4.7 T animal scanner with an average voxel size within the rat hippocampus of 10 μl. In LH rats hippocampal creatine/NAA rose significantly (14%) whereas creatine/NAA of NLH rats showed no increase at all. A possible connection between hippocampal creatine levels and major depressive disorders as a reflection of changes in energy metabolism is discussed.
We investigated the effects of acute i.v. administration of 2 mg of delta 9-tetrahydrocannabinol (THC) on regional brain glucose metabolism using 18F-2-fluoro-2-deoxyglucose and positron emission tomography (PET) in eight normal subjects. Subjects were tested twice: during baseline conditions and 30-40 min after THC administration. Changes in global cerebral glucose metabolism in response to THC were variable: three subjects showed an increase, three showed a decrease, and two showed no change. In contrast, all subjects showed an increase in normalized metabolism in the cerebellum following THC administration. Cerebellar changes were the only significant regional metabolic changes due to THC administration. The increase in metabolic activity in the cerebellum was correlated with the subjective sense of THC intoxication and with plasma THC concentration. Cerebellar localization of metabolic effects due to THC administration corresponds well with the high density of cannabinoid receptors known to be in this area.
The evidence for long-term cognitive impairments associated with chronic use of cannabis has been inconclusive. We report the results of a brain event-related potential (ERP) study of selective attention in long-term cannabis users in the unintoxicated state. Two ERP measures known to reflect distinct components of attention were found to be affected differentially by duration and frequency of cannabis use. The ability to focus attention and filter out irrelevant information, measured by frontal processing negativity to irrelevant stimuli, was impaired progressively with the number of years of use but was unrelated to frequency of use. The speed of information processing, measured by the latency of parietal P300, was delayed significantly with increasing frequency of use but was unaffected by duration of use. The results suggest that a chronic buildup of cannabinoids produces both short- and long-term cognitive impairments.
The purpose of the present study was to investigate the disruptive effects of cannabinoids on working memory as assessed in the eight-arm radial-maze. Systemic administration of delta 9-THC, WIN-55,212-2, and CP-55,940 increased the number of errors committed in the radial-maze. CP-55,940 was the most potent cannabinoid in impairing memory (ED50 = 0.13 mg/kg). delta 9-THC and WIN-55,212-2 disrupted maze-choice accuracy at equipotent doses (ED50 values = 2.1 and 2.2 mg/kg, respectively). In addition, systemic administration of each of these agents retarded completion time. Whereas the doses of delta 9-THC and CP-55,940 required to retard maze performance were higher than those needed to increase error numbers, WIN-55,212-2 was equipotent in both of these measures. On the other hand, neither anandamide, the putative endogenous cannabinoid ligand, nor cannabidiol, an inactive naturally occurring cannabinoid, had any apparent effects on memory. A second aim of this study was to elucidate the neuroanatomical substrates mediating the disruptive effects of cannabinoids on memory. Intrahippocampal injections of CP-55,940 impaired maze performance in a dose-dependent manner (ED50 = 8 micrograms/rat), but did not retard the amount of time required to complete the maze. The effects of intrahippocampal CP-55,940 were apparently specific to cognition because no other cannabinoid pharmacological effects (e.g., antinociception, hypothermia, and catalepsy) were detected. This dissociation between choice accuracy in the radial-maze and other cannabinoid pharmacological effects suggests that the working memory deficits produced by cannabinoids may be mediated by cannabinoid receptors in the hippocampus.
The present paper describes a sensitive method developed in our laboratory for the simultaneous analysis of opiates (morphine, codeine and monoacetylmorphine), cocainis (cocaine and benzoylecgonine) and cannabinoids (delta 9-tetrahydrocannabinol and 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid) in hair samples. After decontaminating the sample with dichloromethane, two consecutive hydrolyses were performed in order to achieve the best conditions for extracting the three kinds of drugs from the protein matrix. First the opiate and cocainic compounds were extracted by means of a soft acidic hydrolysis with 0.1 N HCl at 50 degrees C overnight and organic solvent extraction at pH 9.2. The cannabinoids need a stronger basic hydrolysis with 11.8 N KOH for 10 min at laboratory temperature. After adding maleic acid, the cannabinoids were extracted with an organic solvent. The derivatization was carried out with heptafluorobutyric anhydride and hexafluoropropanol. Calibration curves were linear between 0.5-100 ng/mg of hair. Recovery and reproducibility were assured. The quantification limits ranged between 0.04-0.26 ng/mg of hair. Seventy hair samples from known drug abusers were cut into 1-cm segments and analyzed by this method. The ranges of measured concentrations (ng/mg) were 0.31-89 for cocaine, 0.1-5.76 for benzoylecgonine, 0.34-45.79 for morphine, 0.45-39.59 for codeine, 0.09-48.18 for monoacetylmorphine, 0.06-7.63 for THC and 0.06-3.87 for THC-COOH. The results of sectional analyses agreed with the self reported drug histories. The usefulness of this method is in assessing earlier drug consumption, and also at the same time obtaining a chronological profile of the consumption of these three types of drugs.
The distribution and density of cannabinoid receptor binding and messenger RNA expression in aged human brain were examined in several forebrain and basal ganglia structures. In vitro binding of [3H]CP-55,940, a synthetic cannabinoid, was examined by autoradiography in fresh frozen brain sections from normal aged humans (n = 3), patients who died with Alzheimer's disease (n = 5) and patients who died with other forms of cortical pathology (n = 5). In the structures examined--hippocampal formation, neocortex, basal ganglia and parts of the brainstem--receptor binding showed a characteristic pattern of high densities in the dentate gyrus molecular layer, globus pallidus and substantia nigra pars reticulata, moderate densities in the hippocampus, neocortex, amygdala and striatum, and low densities in the white matter and brainstem. In situ hybridization histochemistry of human cannabinoid receptor, a ribonucleotide probe for the human cannabinoid receptor messenger RNA, showed a pattern of extremely dense transcript levels in subpopulations of cells in the hippocampus and cortex, moderate levels in hippocampal pyramidal neurons and neurons of the striatum, amygdala and hypothalamus, and no signal over dentate gyrus granule cells and most of the cells of the thalamus and upper brainstem, including the substantia nigra. In Alzheimer's brains, compared to normal brains, [3H]CP-55,940 binding was reduced by 37-45% in all of the subfields of the hippocampal formation and by 49% in the caudate. Lesser reductions (20-24%) occurred in the substantia nigra and globus pallidus, internal segment. Other neocortical and basal ganglia structures were not different from control levels. Levels of messenger RNA expression did not differ between Alzheimer's and control brains, but there were regionally discrete statistically significant losses of the intensely expressing cells in the hippocampus. The reductions in binding did not correlate with or localize to areas showing histopathology, estimated either on the basis of overall tissue quality or silver staining of neuritic plaques and neurofibrillary tangles. Reduced [3H]55,940 binding was associated with increasing age and with other forms of cortical pathology, suggesting that receptor losses are related to the generalized aging and/or disease process and are not selectively associated with the pathology characteristic of Alzheimer's disease, nor with overall decrements in levels of cannabinoid receptor gene expression.
Hair samples taken from 850 individuals with presumed drug abuse were tested simultaneously for delta 9-tetrahydrocannabinol (THC), cocaine, heroin, the primary heroin metabolite 6-monoacetylmorphine (6-MAM) and morphine. The drugs were extracted with methanol under sonication. Compared to other extraction procedures this solvent extraction technique provides high extraction yields and less experimental effort. The analyses were carried out using gas chromatography-mass spectrometry (GCMS) in selected ion monitoring (SIM) mode. This procedure allows the simultaneous detection of amphetamine, methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA) and methylenedioxylamphetamine (MDE). THC was found in 104 (12.2%), cocaine in 230 (27%) and 6-MAM in 141 (16.6%) samples. In addition to 6-MAM, morphine was detected in 87 (10.2%) and heroin in 38 samples (4.5%). The concentrations found were in a range 0.009-16.7 ng/mg for THC, 0.037-129.68 ng/mg for cocaine, 0.028-79.82 ng/mg for 6-MAM, 0.045-53.14 ng/mg for heroin and 0.011-7.800 ng/mg for morphine. The statistical distribution of the drug concentrations compared with the self-reported consumption behaviour of the users may possibly lead to a better understanding of the relationship between drug dosage and corresponding concentrations in hair.
We have carried out single-voxel proton magnetic resonance spectroscopy centered on the putamen both ipsilateral and contralateral to the worst affected side in nine subjects with drug naive idiopathic Parkinson's disease (IPD); seven chronically levodopa-treated dyskinetic IPD subjects; and 11 age-matched healthy controls. Measurements of N-acetylaspartate (NAA)/choline (Cho), NAA/(Creatine + Phosphocreatine) (Cr + PCr), and Cho/(Cr + PCr) were made. We found a significant reduction in NAA/Cho ratios from the putamen contralateral to the most affected side in the drugnaive group (p = 0.009), but not the levodopa-treated IPD groups compared with controls. There were no significant differences in NAA/(Cr + PCr) or Cho/(Cr + PCr) ratios. In untreated IPD, reduced putaminal NAA/Cho ratios may reflect loss of nigrostriatal dopamine terminals or alternatively indicate a functional abnormality of striatal putaminal neurons, such as membrane dysfunction due to striatal deafferentation. This study suggests that NAA/Cho ratios may be affected by L-dopa therapy and this may provide a reversible marker of neuronal dysfunction in the striatum.
The anatomical distribution and density of cannabinoid receptors in the human brain was studied in one fetal (33 weeks gestation), two neonatal (aged three to six months) and eight adult (aged 21-81 years) human cases using quantitative receptor autoradiography following in vitro labelling of sections with the synthetic cannabinoid agonist [3H]CP55,940. Cannabinoid receptors were distributed in a heterogeneous fashion throughout the adult human brain and spinal cord. The allocortex contained very high concentrations of cannabinoid receptor binding sites in the dentate gyrus, Ammons's horn and subiculum of the hippocampal formation; high concentrations of receptors were also present in the entorhinal cortex and amygdaloid complex. Cannabinoid receptor binding sites were also present throughout all regions of the neocortex, where they showed a marked variation in density between the primary, secondary and associational cortical regions: the greatest densities of receptors were present in the associational cortical regions of the frontal and limbic lobes, with moderate densities in the secondary sensory and motor cortical regions, and with the lowest densities of receptors in the primary sensory and motor cortical regions. Relatively high concentrations of cannabinoid receptors were consistently seen in cortical regions of the left (dominant) hemisphere, known to be associated with verbal language functions. In all of the cortical regions, the pattern and density of receptor labelling followed the neocortical laminar organization, with the greatest density of receptors localized in two discrete bands--a clearly delineated narrow superficial band which coincided with lamina I and a deeper broader, conspicuous band of labelling which corresponded to laminae V and VI. Labelling in the intervening cortical laminae (II-IV) showed lower densities, with a well delineated narrow band of label in the middle of laminae IV in the associational cortical regions. The thalamus showed a distinctive heterogeneous distribution of cannabinoid receptors, with the highest concentration of receptors localized in the mediodorsal nucleus, anterior nuclear complex, and in the midline and intralaminar complex of nuclei, i.e. in thalamic nuclei which have connectional affiliations with the associational cortical areas. The basal ganglia showed a distinctive heterogeneous pattern of receptor binding, with the very highest concentrations in the globus pallidus internus, moderate concentrations in the globus pallidus externus and ventral pallidum, and moderately low levels of binding throughout the striatal complex. In the midbrain, some of the highest levels of cannabinoid receptor binding sites in the human brain were present in the substantia nigra pars reticulata, with very low levels of labelling in all other midbrain areas. The highest densities of cannabinoid receptor binding in the hindbrain were localized in the molecular layer of the cerebellar cortex and the dorsal motor nucleus of the vagus, with moderate densities of receptors in the nucleus of the solitary tract. The spinal cord showed very low levels of receptor binding. Studies on the distribution of cannabinoid receptors in the fetal and neonatal human brain showed similar patterns of receptor distribution to that observed in the adult human brain, except that the density of receptor binding was generally markedly higher, especially in the basal ganglia and substantia nigra. The pattern of cannabinoid receptor labelling in the striatum showed a striking patchy pattern of organization which was especially conspicuous in the fetal brain. These results show that cannabinoid receptor binding sites in the human brain are localized mainly in: forebrain areas associated with higher cognitive functions; forebrain, midbrain and hindbrain areas associated with the control of movement; and in hindbrain areas associated with the control of motor and sensory functions of the autonomic nervous system. (AB
Cannabis is the most widely used illicit drug in many developed societies. Its health and psychological effects are not well understood and remain the subject of much debate, with opinions on its risks polarised along the lines of proponents' views on what its legal status should be. An unfortunate consequence of this polarisation of opinion has been the absence of any consensus on what health information the medical profession should give to patients who are users or potential users of cannabis. There is conflicting evidence about many of the effects of cannabis use, so we summarise the evidence on the most probable adverse health and psychological consequences of acute and chronic use. This uncertainty, however, should not prevent medical practitioners from advising patients about the most likely ill-effects of their cannabis use. Here we make some suggestions about the advice doctors can give to patients who use, or are contemplating the use, of this drug.
Volumetric proton magnetic resonance spectroscopic imaging (MRSI) was used to generate brain metabolite maps in 15 young and 19 elderly adult volunteers. All subjects also had structural MR scans, and a model, which took into account the underlying structural composition of the brain contributing to each metabolite voxel, was developed and used to estimate the concentration of the N-acetyl-moiety (NAc), creatine (Cr), and choline (Cho) in gray matter and white matter. NAc concentration (signal intensity per unit volume of brain) was higher in gray than white matter and did not differ between young and old subjects despite significant gray matter volume deficits in the older subjects. To the extent that NAc is an index of neuronal integrity, the available gray matter appears to be intact in these older healthy adults. Cr concentrations were much higher in gray than white matter and significantly higher in the old than young subjects. Cho concentration in gray matter was also significantly higher in old than young subjects. Independent determination of metabolite values rather than use of ratios is essential for characterizing age-related changes in brain MRS metabolites.
The purpose of this study was to investigate possible adverse effects of cannabis use on cognitive decline after 12 years in persons under age 65 years. This was a follow-up study of a probability sample of the adult household residents of East Baltimore. The analyses included 1,318 participants in the Baltimore, Maryland, portion of the Epidemiologic Catchment Area study who completed the Mini-Mental State Examination (MMSE) during three study waves in 1981, 1982, and 1993-1996. Individual MMSE score differences between waves 2 and 3 were calculated for each study participant. After 12 years, study participants' scores declined a mean of 1.20 points on the MMSE (standard deviation 1.90), with 66% having scores that declined by at least one point. Significant numbers of scores declined by three points or more (15% of participants in the 18-29 age group). There were no significant differences in cognitive decline between heavy users, light users, and nonusers of cannabis. There were also no male-female differences in cognitive decline in relation to cannabis use. The authors conclude that over long time periods, in persons under age 65 years, cognitive decline occurs in all age groups. This decline is closely associated with aging and educational level but does not appear to be associated with cannabis use.
Cannabinoids have a long history of consumption for recreational and medical reasons. The primary active constituent of the hemp plant Cannabis sativa is delta9-tetrahydrocannabinol (delta9-THC). In humans, psychoactive cannabinoids produce euphoria, enhancement of sensory perception, tachycardia, antinociception, difficulties in concentration and impairment of memory. The cognitive deficiencies seem to persist after withdrawal. The toxicity of marijuana has been underestimated for a long time, since recent findings revealed delta9-THC-induced cell death with shrinkage of neurons and DNA fragmentation in the hippocampus. The acute effects of cannabinoids as well as the development of tolerance are mediated by G protein-coupled cannabinoid receptors. The CB1 receptor and its splice variant CB1A, are found predominantly in the brain with highest densities in the hippocampus, cerebellum and striatum. The CB2 receptor is found predominantly in the spleen and in haemopoietic cells and has only 44% overall nucleotide sequence identity with the CB1 receptor. The existence of this receptor provided the molecular basis for the immunosuppressive actions of marijuana. The CB1 receptor mediates inhibition of adenylate cyclase, inhibition of N- and P/Q-type calcium channels, stimulation of potassium channels, and activation of mitogen-activated protein kinase. The CB2 receptor mediates inhibition of adenylate cyclase and activation of mitogen-activated protein kinase. The discovery of endogenous cannabinoid receptor ligands, anandamide (N-arachidonylethanolamine) and 2-arachidonylglycerol made the notion of a central cannabinoid neuromodulatory system plausible. Anandamide is released from neurons upon depolarization through a mechanism that requires calcium-dependent cleavage from a phospholipid precursor in neuronal membranes. The release of anandamide is followed by rapid uptake into the plasma and hydrolysis by fatty-acid amidohydrolase. The psychoactive cannabinoids increase the activity of dopaminergic neurons in the ventral tegmental area-mesolimbic pathway. Since these dopaminergic circuits are known to play a pivotal role in mediating the reinforcing (rewarding) effects of the most drugs of abuse, the enhanced dopaminergic drive elicited by the cannabinoids is thought to underlie the reinforcing and abuse properties of marijuana. Thus, cannabinoids share a final common neuronal action with other major drugs of abuse such as morphine, ethanol and nicotine in producing facilitation of the mesolimbic dopamine system.
The authors performed a MRSI study of the anterior cingulate gyrus in 19 schizophrenic patients under stable medication and 16 controls in order to corroborate previous findings of reduced NAA in the anterior cingulate region in schizophrenia. Furthermore, correlations between NAA in the anterior cingulate gyrus and age or illness duration have been determined. A decreased NAA signal was found in the anterior cingulate gyrus of patients compared to controls. Subdividing the patient group into two groups depending on medication revealed that the group of patients receiving a typical neuroleptic medication showed a lower mean NAA in comparison to the group of patients receiving atypical antipsychotic drugs. No significant group differences in the creatine and phosphocreatine signal or the signal from choline-containing compounds were found. The NAA signal significantly correlated with age, and therefore, individual NAA values were corrected for the age effect found in the control group. The age-corrected NAA signal in schizophrenia correlated significantly with the duration of illness. The detected correlations of NAA decrease with age and illness duration are consistent with recent imaging studies where progressing cortical atrophy in schizophrenia was found. Further studies will be needed to corroborate a possible favorable effect of atypical antipsychotics on the NAA signal.
Phospholipase A(2) catalyzes the hydrolysis of membrane glycerophospholipids leading to the production of metabolites observable by both 1H and 31P magnetic resonance spectroscopy. The signal of choline-containing compounds (Cho) observed by 1H magnetic resonance spectroscopy is constituted of metabolites of phosphatidylcholine, especially phosphocholine (PCho) and glycerophosphocholine (GPCho). The phosphomonoester (PME) and phosphodiester (PDE) signals observed by 31P magnetic resonance spectroscopy are, respectively, precursors and catabolites of phospholipids. A large number of brain diseases have been reported to cause variations in the intensity of the Cho, PME and PDE signals. Changes in the activity of phospholipase A(2) have been measured in many brain diseases. In this review, the relationships between the results of 1H and 31P magnetic resonance spectroscopy and the phospholipase A(2) assays are analyzed. In many brain diseases, the variation in the Cho signal intensity can be correlated with a stimulation or inhibition of the phospholipase A(2) activity.
We monitored the effect of electroconvulsive therapy (ECT) on the nuclear magnetic resonance-detectable metabolites N-acetylaspartate, creatine and phosphocreatine, and choline-containing compounds in the hippocampus by means of hydrogen 1 magnetic resonance spectroscopic imaging. We hypothesized that if ECT-induced memory deterioration was associated with neuronal loss in the hippocampus, the N-acetylaspartate signal would decrease after ECT and any increased membrane turnover would result in an increase in the signal from choline-containing compounds.
Seventeen patients received complete courses of ECT, during which repeated proton magnetic resonance spectroscopic imaging studies of the hippocampal region were performed. Individual changes during the course of ECT were compared with values obtained in 24 healthy control subjects and 6 patients remitted from major depression without ECT.
No changes in the hippocampal N-acetylaspartate signals were detected after ECT. A significant mean increase of 16% of the signal from choline-containing compounds after 5 or more ECT treatments was observed. Despite the mostly unilateral ECT application (14 of 17 patients), the increase in the choline-containing compound signal was observed bilaterally. Lactate or elevated lipid signals were not detected. All patients showed clinical amelioration of depression after ECT.
Electroconvulsive therapy is not likely to induce hippocampal atrophy or cell death, which would be reflected by a decrease in the N-acetylaspartate signal. Compared with an age-matched control group, the choline-containing compounds signal in patients with a major depressive episode was significantly lower than normal, before ECT and normalized during ECT.
The specific intracellular effects of antipsychotic drugs are largely unknown. Studies in animals have suggested that antipsychotics modify the expression of various intraneuronal proteins, but no analogous in vivo data in humans are available. The objective of the present study was to assess whether antipsychotics modify N-acetylaspartate (an intraneuronal marker of neuronal functional integrity) measures in brains of patients with schizophrenia.
We used proton magnetic resonance spectroscopic imaging to study 23 patients with schizophrenia (DSM-IV diagnosis) using a within-subject design. Patients were studied twice: once while on a stable regimen of antipsychotic drug treatment (for at least 4 weeks) and once while off medication for at least 2 weeks. Several cortical and subcortical regions were assessed, including the dorsolateral prefrontal cortex and the hippocampal area.
Analysis of variance showed that, while on antipsychotics, patients had significantly higher N-acetylaspartate measures in the dorsolateral prefrontal cortex (p =.002). No other region showed any significant effect of treatment.
These results indicate that antipsychotic drugs increase N-acetylaspartate measures selectively in the dorsolateral prefrontal cortices of patients with schizophrenia, suggesting that these drugs modify in a regionally specific manner the function of a population of cortical neurons. N-Acetylaspartate measures may provide a useful tool to further investigate the effects of antipsychotics at the intracellular level.
A number of studies suggested that cannabis use can cause or exacerbate psychoses and may increase the risk of developing schizophrenia. These findings suggest that changes in the cannabinoid system of the brain may be involved in the pathology of schizophrenia. To determine whether changes in the cannabinoid system were present in the brains of subjects with schizophrenia, we used in situ radioligand binding and autoradiography to measure the binding of [3H]CP-55940 to the cannabinoid-1 receptor in the dorsolateral prefrontal cortex (Brodmann's area 9), caudate-putamen and areas of the temporal lobe from schizophrenic and control subjects, some of whom had ingested cannabis close to death. There was an increase in the density of [3H]CP-55940 binding to cannabinoid-1 receptors in the dorsolateral prefrontal cortex from subjects with schizophrenia (mean+/-S.E.M.: 142+/-9.9 vs 119+/-6.6fmol/mg estimated tissue equivalents; P<0.05) that was independent of recent cannabis ingestion. There was an increase in the density of cannabinoid-1 receptors in the caudate-putamen from subjects who had recently ingested cannabis (151+/-9.0 vs 123+/-7.2fmol/mg estimated tissue equivalents; P<0.05) that was independent of diagnoses. These data indicate that there are changes in cannabinoid-1 receptors in the dorsolateral prefrontal cortex that may prove to be associated with the pathology of schizophrenia. By contrast, changes in the density of cannabinoid-1 receptors may occur in the caudate-putamen in response to cannabis ingestion.
Cannabinoid receptor activation in vivo reduces ischemic injury, a phenomenon that has not been successfully reproduced in vitro. Because cyclic adenosine monophosphate (cAMP) levels are radically elevated during ischemic reperfusion, but cannabinoid receptor activation reduces cAMP levels, we hypothesized that cannabinoids might prevent in vitro glutamate toxicity if reperfusion was simulated by cAMP supplementation after glutamate removal. Although neuronal cultures were unaffected by the single addition of either cannabinoid or dibutyryl cAMP (dbcAMP), glutamate toxicity was reduced by 20% when cannabinoid was present during glutamate exposure and either dbcAMP or forskolin was added after glutamate removal. Further studies revealed that cannabinoid receptor activation reduces glutamate toxicity by attenuating calcium influx through N- and P/Q-type calcium channels. The effect of glutamate exposure on neuronal cAMP levels was also examined. Glutamate exposure significantly reduced neuronal cAMP levels, although suppression was even greater when cannabinoid was present. Because neurological outcome after ischemia is poor when cAMP levels during reperfusion are low, it is hypothesized that cAMP elevation after glutamate exposure may offset excitotoxic and/or cannabinoid receptor-induced cAMP depletion. Cannabinoids protect against ischemic injury in vivo, but only reduce toxicity in vitro when cAMP levels are elevated, possibly suggesting that cAMP elevation during reperfusion reduces brain injury by off-setting the effect of Gi/o protein-coupled systems on adenylate cyclase.
Differences in proton MRS T(2) values for phosphocreatine (PCr) and creatine (Cr) methyl groups (3.0 ppm) were investigated in studies of phantoms and human brain. Results from phantom studies revealed that T(2) of PCr in solution is significantly shorter than T(2) of Cr. Curve-fitting results indicated that the amplitude-TE curves of the total Cr resonance at 3.0 ppm in human brain (N = 26) fit a biexponential decay model significantly better than a monoexponential decay model (P < 0.006), yielding mean T(2) values of 117 +/- 21 ms and 309 +/- 21 ms. Using a localized, long-TE (272 ms) point-resolved spectroscopy (PRESS) proton MRS during 2 min of photic stimulation (PS), an increase of 12.1% +/- 3.5% in the mean intensity of the total Cr resonance in primary visual cortex (VI) was observed at the end of stimulation (P < 0.021). This increase is consistent with the conversion of 26% of PCr in VI to Cr, which is concordant with (31)P MRS findings reported by other investigators. These results suggest a significantly shorter T(2) for PCr than for Cr in vivo. This difference possibly could be exploited to quantify regional activation in functional spectroscopy studies, and could also lead to inaccuracies in some circumstances when the Cr resonance is used as an internal standard for (1)H MRS studies in vivo.