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Wayne Hall - One of the best experts on this subject based on the ideXlab platform.
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The mental health Effects of Cannabis use
New Oxford Textbook of Psychiatry, 2020Co-Authors: Wayne HallAbstract:The major adverse acute psychological Effects of Cannabis use are as follows: ♦ Anxiety, dysphoria, panic, and paranoia, especially in naive users ♦ Impairment of attention, memory, and psychomotor performance while intoxicated ♦ An increased risk of accident if an intoxicated person attempts to drive a vehicle. The major psychological Effects of daily heavy Cannabis use over many years remain contested but probably include the following: ♦ A Cannabis-dependence syndrome ♦ Subtle forms of cognitive impairment that affect attention and memory and which persist while the user remains chronically intoxicated ♦ Impaired educational achievement in adolescents with a history of poor school performance, whose achievement may be limited by the cognitive impairments produced by chronic intoxication with Cannabis ♦ Among those who initiate Cannabis use in the early teens, a higher risk of progressing to heavy Cannabis and other illicit drug use, and becoming dependent on Cannabis.
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The health and psychological Effects of Cannabis use
Current Issues in Criminal Justice, 2018Co-Authors: Wayne HallAbstract:This is an updated version of a review of the health and psychological Effects of Cannabis use that was commissioned in May 1992 by the Australian National Task Force on Cannabis. The earlier review (Hall, Solowij and Lemon, 1994) has been updated in the light of recent research and the reviews of the literature (WHO, 1997; US Institute of Medicine, 1998). The section of chapter 5 dealing with Cannabis and cancer has been published as an editorial in Addiction. We would like to thank the following individuals for their assistance in preparing this review and the original version on which it was based
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Challenges in minimizing the adverse Effects of Cannabis use after legalization.
Social Psychiatry and Psychiatric Epidemiology, 2015Co-Authors: Wayne HallAbstract:Over the past 20 years epidemiological studies have left us better informed about the adverse Effects of regular Cannabis use in young adulthood on mental health and psychosocial outcomes [1]. The Christchurch Health and Development Study (CHDS) of David Fergusson and colleagues has made an especially valuable contribution to this literature, as indicated by the summary of its key findings on the mental health and psychosocial outcomes of Cannabis use in the current issue. The CHDS followed the life course of a birth cohort of 1000 New Zealanders, 80 % of whom had used Cannabis by their mid-20s. Nearly a third used Cannabis regularly enough, and for long enough, to enable assessment of associations between common adverse psychosocial and mental health outcomes and regular Cannabis use. The study also collected detailed information on the personal and social situations of the cohort that enabled the researchers to assess whether the associations they observed between daily Cannabis use and adverse outcomes could be explained by pre-existing differences between those who had and had not used Cannabis regularly. This study has consistently found associations between daily Cannabis use and poor mental health and psychosocial outcomes. Daily Cannabis users had poorer educational attainment in adolescence and poorer employment outcomes in young adulthood, were more likely to use other illicit drugs, and were more likely to report more symptoms of psychosis, depression and suicide. Many of these risks increased with the intensity of Cannabis use, and these associations persisted after statistical adjustment for plausible confounding factors. Many of these results have been replicated in the Dunedin birth cohort (e.g. [2]), and in longitudinal studies in other countries such as Australia (e.g. [3]), Germany [4] and the Netherlands [5]. Fergusson and colleagues show that the adverse health Effects of Cannabis are most concentrated among daily users (nearly 20 % of those who ever used the drug). This pattern was most common among young people who began using Cannabis in their mid-teens and continued to use daily throughout young adulthood. Not all Cannabis users experienced harm: many adolescent users did not use Cannabis regularly enough or for long enough to do so; and a substantial proportion of adult Cannabis users, the majority of whom reported using Cannabis less than daily, did not report any harms related to their Cannabis use. The Cannabis policy debate has been presented in many countries as a forced choice between two packages of belief: (1) that Cannabis use does not harm users, and so it should be legalized to avoid users acquiring criminal records; and (2) that Cannabis use can harm some users, and so we should continue to prohibit its use [1]. This framing has often hindered a fair appraisal of the adverse health Effects of Cannabis. Evidence on the harms of Cannabis use cannot decide Cannabis policy [6]. The policy choice will depend upon societal beliefs about the priority that should be given to competing social values, such as, preserving individual freedom and protecting human health and well-being. It will also depend on political views on the extent to which the state should use criminal law to prevent adults from & Wayne Hall w.hall@uq.edu.au
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does Cannabis use increase the risk of death systematic review of epidemiological evidence on adverse Effects of Cannabis use
Drug and Alcohol Review, 2010Co-Authors: Bianca Calabria, Wayne Hall, Louisa Degenhardt, Michael T LynskeyAbstract:ISSUES: To conduct a comprehensive search of the peer-reviewed literature to assess risk of Cannabis-related mortality. APPROACH: Systematic peer-reviewed literature searches were conducted in Medline, EMBASE and PsycINFO to identify data on mortality associated with Cannabis use. Search strings for Cannabis and mortality were used. Searches were limited to human subjects and the publication timeframe of January 1990 to January 2008. Reference lists of review articles and of specific studies deemed important by colleagues were searched to identify additional studies. A list of the selected articles was emailed to experts in the field asking for comment on completeness. KEY FINDINGS: There is insufficient evidence, particularly because of the low number of studies, to assess whether the all-cause mortality rate is elevated among Cannabis users in the general population. Case-control studies suggest that some adverse health outcomes may be elevated among heavy Cannabis users, namely, fatal motor vehicle accidents, and possibly respiratory and brain cancers. The evidence is as yet unclear as to whether regular Cannabis use increases the risk of suicide. CONCLUSIONS: There is a need for long-term cohort studies that follow Cannabis using individuals into old age, when the likelihood of any detrimental Effects of Cannabis use are more likely to emerge among those who persist in using Cannabis into middle age and older. Case-control studies of Cannabis use and various causes of mortality are also needed.
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the adverse health Effects of Cannabis use what are they and what are their implications for policy
International Journal of Drug Policy, 2009Co-Authors: Wayne HallAbstract:Background: The adverse health Effects of Cannabis are a source of contention in debates about policies towards the drug. Methods: This paper provides a review of epidemiological evidence on the major adverse health Effects of Cannabis use and considers its implications for policy. Results: The evidence strongly suggests that Cannabis can adversely affect some users, especially adolescents who initiate use early and young adults who become regular users. These adverse Effects probably include increased risks of: motor vehicle crashes, the development of Cannabis dependence, impaired respiratory function, cardiovascular disease, psychotic symptoms, and adverse outcomes of adolescent development, namely, poorer educational outcomes and an increased likelihood of using other illicit drugs. Conclusions: Politically, evidence of adverse health Effects favours the status quo in developed countries like Australia where Cannabis policy has been framed by the media as a choice between two views: (1) either Cannabis use is largely harmless to most users and so we should legalize, or at the very least decriminalize its use; or (2) it harms some of its users so we should continue to prohibit its use.
Sagnik Bhattacharyya - One of the best experts on this subject based on the ideXlab platform.
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Unraveling the Intoxicating and Therapeutic Effects of Cannabis Ingredients on Psychosis and Cognition.
Frontiers in Psychology, 2020Co-Authors: Marco Colizzi, Mirella Ruggeri, Sagnik BhattacharyyaAbstract:Research evidence suggests a dose-response relationship for the association between Cannabis use and risk of psychosis. Such relationship seems to reflect an increased risk of psychosis not only as a function of frequent Cannabis use, but also of high-potency Cannabis use in terms of concentration of Δ-9-tetrahydrocannabinol (Δ9-THC), its main psychoactive component. This finding would be in line with the evidence that Δ9-THC administration induces transient psychosis-like symptoms in otherwise healthy individuals. Conversely, low-potency varieties would be less harmful because of their lower amount of Δ9-THC and potential compresence of another cannabinoid, cannabidiol (CBD), which seems to mitigate Δ9-THC detrimental Effects. A growing body of studies begins to suggest that CBD may have not only protective Effects against the psychotomimetic Effects of Δ9-THC but even therapeutic properties on its own, opening new prospects for the treatment of psychosis. Despite being more limited, evidence of the Effects of Cannabis on cognition seems to come to similar conclusions, with increasing Δ9-THC exposure being responsible for the cognitive impairments attributed to recreational Cannabis use while CBD preventing such Effects and, when administered alone, enhancing cognition. Molecular evidence indicates that Δ9-THC and CBD may interact with cannabinoid receptors with almost opposite mechanisms, with Δ9-THC being a partial agonist and CBD an inverse agonist/antagonist. With the help of imaging techniques, pharmacological studies in vivo have been able to show opposite Effects of Δ9-THC and CBD also on brain function. Altogether, they may account for the intoxicating and therapeutic Effects of Cannabis on psychosis and cognition.
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Residual Effects of Cannabis use in adolescent and adult brains - A meta-analysis of fMRI studies.
Neuroscience & Biobehavioral Reviews, 2018Co-Authors: Grace Blest-hopley, Vincent Giampietro, Sagnik BhattacharyyaAbstract:Abstract While numerous studies have investigated the residual Effects of Cannabis use on human brain function, results of these studies have been inconsistent. Using meta-analytic approaches we summarize the Effects of prolonged Cannabis exposure on human brain function as measured using task-based functional MRI (fMRI) across studies employing a range of cognitive activation tasks comparing regular Cannabis users with non-users. Separate meta-analyses were carried out for studies investigating adult and adolescent Cannabis users. Systematic literature search identified 20 manuscripts (13 adult and 7 adolescent studies) meeting study inclusion criteria. Adult analyses compared 530 Cannabis users to 580 healthy controls while adolescent analyses compared 219 Cannabis users to 224 healthy controls. In adult Cannabis users brain activation was increased in the superior and posterior transverse temporal and inferior frontal gyri and decreased in the striate area, insula and middle temporal gyrus. In adolescent Cannabis users, activation was increased in the inferior parietal gyrus and putamen compared to healthy controls. Functional alteration in these areas may reflect compensatory neuroadaptive changes in Cannabis users.
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The Effects of Cannabis use on salience attribution: a systematic review
Acta Neuropsychiatrica, 2016Co-Authors: Surapi Bhairavi Wijayendran, Aisling O'neill, Sagnik BhattacharyyaAbstract:Objective The relationship between Cannabis use and the onset of psychosis is well established. Aberrant salience processing is widely thought to underpin many of these symptoms. Literature explicitly investigating the relationship between aberrant salience processing and Cannabis use is scarce; with those few studies finding that acute tetrahydrocannabinol (THC) administration (the main psychoactive component of Cannabis) can result in abnormal salience processing in healthy cohorts, mirroring that observed in psychosis. Nevertheless, the extent of and mechanisms through which Cannabis has a modulatory effect on aberrant salience, following both acute and chronic use, remain unclear. Methods Here, we systematically review recent findings on the Effects of Cannabis use – either through acute THC administration or in chronic users – on brain regions associated with salience processing (through functional MRI data); and performance in cognitive tasks that could be used as either direct or indirect measures of salience processing. We identified 13 studies either directly or indirectly exploring salience processing. Three types of salience were identified and discussed – incentive/motivational, emotional/affective, and attentional salience. Results The results demonstrated an impairment of immediate salience processing, following acute THC administration. Amongst the long-term Cannabis users, normal salience performance appeared to be underpinned by abnormal neural processes. Conclusions Overall, the lack of research specifically exploring the Effects of Cannabis use on salience processing, weaken any conclusions drawn. Additional research explicitly focussed on salience processing and Cannabis use is required to advance our understanding of the neurocognitive mechanisms underlying the association between Cannabis use and development of psychosis.
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the Effects of Cannabis on memory function in users with and without a psychotic disorder findings from a combined meta analysis
Psychological Medicine, 2016Co-Authors: Tabea Schoeler, Joseph Kambeitz, I Behlke, Robin M Murray, Sagnik BhattacharyyaAbstract:Background.Effect of Cannabis use on memory function is a contentious issue, with Effects being different in healthy individuals and patients with psychosis.Method.Employing a meta-analytic approach we investigated the Effects of Cannabis use on memory function in patients with psychosis and healthy individuals, and the effect of diagnosis, memory dimension and moderating factors. A total of 88 studies were identified through a systematic literature search, investigating healthy (n = 7697) and psychotic (n = 3261) individuals. Standardized mean differences between the Cannabis user and non-user groups on memory tasks were estimated using random-Effects models and the effect-size statistic Cohen's d. Effects of potential moderating factors were tested using mixed-Effects models and subgroup analyses.Results.We found that Cannabis use was associated with significantly (p 0.05) impaired global (d = 0.27) and prospective memory (d = 0.61), verbal immediate (d = 0.40) and delayed (d = 0.36) recall as well as visual recognition (d = 0.41) in healthy individuals, but a better global memory (d = -0.11), visual immediate recall (d = -0.73) and recognition (d = -0.42) in patients. Lower depression scores and younger age appeared to attenuate the Effects of Cannabis on memory. Cannabis-using patients had lower levels of depression and were younger compared with non-using patients, whilst healthy Cannabis-users had higher depression scores than age-matched non-users. Longer duration of abstinence from Cannabis reduced the Effects on memory in healthy and patient users.Conclusions.These results suggest that Cannabis use is associated with a significant domain-specific impairment in memory in healthy individuals but not in Cannabis-using patients, suggesting that they may represent a less developmentally impaired subgroup of psychotic patients.
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Acute and Non-acute Effects of Cannabis on Human Memory Function: A Critical Review of Neuroimaging Studies
Current Pharmaceutical Design, 2014Co-Authors: Matthijs G. Bossong, Sagnik Bhattacharyya, Gerry Jager, Paul AllenAbstract:Smoking Cannabis produces a diverse range of Effects, including impairments in learning and memory. These Effects are exerted through action on the endocannabinoid system, which suggests involvement of this system in human cognition. Learning and memory deficits are core symptoms of psychiatric and neurological disorders such as schizophrenia and Alzheimer’s disease, and may also be related to endocannabinoid dysfunction in these disorders. However, before new research can focus on potential treatments that work by manipulating the endocannabinoid system, it needs to be elucidated how this system is involved in symptoms of psychiatric disorders. Here we review neuroimaging studies that investigated acute and non-acute Effects of Cannabis on human learning and memory function, both in adults and in adolescents. Overall, results of these studies show that Cannabis use is associated with a pattern of increased activity and a higher level of deactivation in different memory-related areas. This could reflect either increased neural effort (‘neurophysiological inefficiency’) or a change in strategy to maintain good task performance. However, the interpretation of these findings is significantly hampered by large differences between study populations in Cannabis use in terms of frequency, age of onset, and time that subjects were abstinent from Cannabis. Future neuroimaging studies should take these limitations into account, and should focus on the potential of cannabinoid compounds for treatment of cognitive symptoms in psychiatric disorders.
Raul Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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Nonacute Effects of Cannabis use on motivation and reward sensitivity in humans: A systematic review.
Psychology of Addictive Behaviors, 2018Co-Authors: Ileana Pacheco-colón, Jorge M. Limia, Raul GonzalezAbstract:: Reduced motivation is often noted as a consequence of Cannabis use. However, prior studies examining this association have suboptimally operationalized motivation and have yielded mixed findings. This review discusses motivation and the closely related construct of reward sensitivity. We summarize the available literature examining associations between motivation and Cannabis use, addressing the following questions: (a) Is there evidence for decreased motivation among Cannabis users? (b) Is there evidence that lack of motivation among Cannabis users is specific to their use of Cannabis (rather than to use of other addictive drugs)? and (c) Is there evidence suggesting a causal relationship between Cannabis use and motivation? Using PubMed, PsycINFO, and WebofScience, we conducted a literature search of studies examining nonacute Effects of Cannabis use on motivation, apathy, amotivation, effort, and reward sensitivity in humans. This search yielded 22 studies, which were reviewed in detail. We conclude that, although cross-sectional evidence of a Cannabis-specific effect on motivation is equivocal, there is partial support from longitudinal studies for a causal link between Cannabis use and reduced motivation. Additionally, we propose that reward sensitivity and motivation represent distinct yet related constructs and that reductions in one may not always lead to reductions in the other. Future work should longitudinally examine associations between Cannabis use, motivation, and reward sensitivity; carefully define and operationalize these constructs; and control for the influence of potential confounding factors. (PsycINFO Database Record
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Effects of Cannabis use on human behavior including cognition motivation and psychosis a review
JAMA Psychiatry, 2016Co-Authors: Nora D Volkow, Raul Gonzalez, James M Swanson, Eden A Evins, Lynn E Delisi, Madeline H Meier, Michael A P Bloomfield, Valerie H Curran, Ruben BalerAbstract:With a political debate about the potential risks and benefits of Cannabis use as a backdrop, the wave of legalization and liberalization initiatives continues to spread. Four states (Colorado, Washington, Oregon, and Alaska) and the District of Columbia have passed laws that legalized Cannabis for recreational use by adults, and 23 others plus the District of Columbia now regulate Cannabis use for medical purposes. These policy changes could trigger a broad range of unintended consequences, with profound and lasting implications for the health and social systems in our country. Cannabis use is emerging as one among many interacting factors that can affect brain development and mental function. To inform the political discourse with scientific evidence, the literature was reviewed to identify what is known and not known about the Effects of Cannabis use on human behavior, including cognition, motivation, and psychosis.
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Effects of Cannabis on neurocognitive functioning recent advances neurodevelopmental influences and sex differences
Neuropsychology Review, 2013Co-Authors: Natania A Crane, Randi Melissa Schuster, Paolo Fusarpoli, Raul GonzalezAbstract:Decades of research have examined the Effects of Cannabis on neurocognition. Recent advances in this field provide us with a better understanding of how Cannabis use influences neurocognition both acutely (during intoxication) and non-acutely (after acute Effects subside). Evidence of problems with episodic memory is one of the most consistent findings reported; however, several other neurocognitive domains appear to be adversely affected by Cannabis use under various conditions. There is significant variability in findings across studies, thus a discussion of potential moderators is increasingly relevant. The purpose of this review was to 1) provide an update on research of Cannabis’ acute and non-acute Effects on neurocognition, with a focus on findings since 2007 and 2) suggest and discuss how neurodevelopmental issues and sex differences may influence Cannabis Effects on neurocognition. Finally we discuss how future investigations may lead to better understanding of the complex interplay among Cannabis, stages of neurodevelopment, and sex on neurocognitive functioning.
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non acute residual neurocognitive Effects of Cannabis use a meta analytic study
Journal of The International Neuropsychological Society, 2003Co-Authors: Igor Grant, Raul Gonzalez, Catherine L Carey, Loki Natarajan, Tanya WolfsonAbstract:The possible medicinal use of cannabinoids for chronic diseases emphasizes the need to understand the long-term Effects of these compounds on the central nervous system. We provide a quantitative synthesis of empirical research pertaining to the non-acute (residual) Effects of Cannabis on the neurocognitive performance of adult human subjects. Out of 1,014 studies retrieved using a thorough search strategy, only 11 studies met essential a priori inclusion criteria, providing data for a total of 623 Cannabis users and 409 non- or minimal users. Neuropsychological results were grouped into 8 ability domains, and effect sizes were calculated by domain for each study individually, and combined for the full set of studies. Using slightly liberalized criteria, an additional four studies were included in a second analysis, bringing the total number of subjects to 1,188 (i.e., 704 Cannabis users and 484 non-users). With the exception of both the learning and forgetting domains, effect size confidence intervals for the remaining 6 domains included zero, suggesting a lack of effect. Few studies on the non-acute neurocognitive Effects of Cannabis meet current research standards; nevertheless, our results indicate that there might be decrements in the ability to learn and remember new information in chronic users, whereas other cognitive abilities are unaffected. However, from a neurocognitive standpoint, the small magnitude of these effect sizes suggests that if Cannabis compounds are found to have therapeutic value, they may have an acceptable margin of safety under the more limited conditions of exposure that would likely obtain in a medical setting. (JINS, 2003, 9, 679‐689.)
Deborah A Yurgeluntodd - One of the best experts on this subject based on the ideXlab platform.
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the residual neuropsychological Effects of Cannabis the current status of research
Drug and Alcohol Dependence, 1995Co-Authors: Harrison G. Pope, Amanda J. Gruber, Deborah A YurgeluntoddAbstract:Abstract Evidence for the residual neuropsychological Effects of Cannabis must first be separated from evidence regarding (i) the acute Effects of the drug, (ii) attributes of heavy Cannabis users, and (iii) actual psychiatric disorders caused or exacerbated by Cannabis. The remaining evidence must then be subdivided into (a) data supporting a ‘drug residue’ effect during the 12–24 h period immediately after acute intoxication and (b) data suggesting a more lasting toxic effect on the central nervous system which persists even after all drug residue has left the system. We reviewed the literature, comparing both ‘drug-administration’ studies in which known amounts of Cannabis were administered to volunteers, and ‘naturalistic studies’ in which heavy marijuana users were tested after some period of abstinence. The data support a ‘drug residue’ effect on attention, psychomotor tasks, and short-term memory during the 12–24 h period immediately after Cannabis use, but evidence is as yet insufficient to support or refute either a more prolonged ‘drug residue’ effect, or a toxic effect on the central nervous system that persists even after drug residues have left the body. We describe possible study designs to address these latter questions.
Ashley C Proal - One of the best experts on this subject based on the ideXlab platform.
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correlates to the variable Effects of Cannabis in young adults a preliminary study
Harm Reduction Journal, 2012Co-Authors: Ariella A Camera, Veronica Tomaselli, Jerry Fleming, Gul A Jabbar, Melissa Trachtenberg, Juan Antonio Galvezbuccollini, Ashley C ProalAbstract:Background: Cannabis use can frequently have adverse affects in those that use it and these can be amplified by various characteristics of an individual, from demographic and environmental variations to familial predisposition for mental illnesses. Methods: The current study of 100 individuals, who were Cannabis users during their adolescence and may still be users, was a survey of the self perceived Effects of Cannabis and their correlates. A reliable family member was also interviewed for determination of family history of various major mental illnesses and substance use. Results: As many as 40% of Cannabis users had paranoid feelings (suspiciousness) when using Cannabis, although the most frequent effect was feeling relaxed (46%). Having a familial background for mental illnesses such as depression or schizophrenia did not determine the Effects of Cannabis nor its pattern of use, although the number of subjects with such a history was small. An age at which an individual began using Cannabis did have an effect on how heavily it was used and the heavier the Cannabis use, the more likely the individual was also to have had psychotic symptoms after use. There were no sex differences in Effects of Cannabis. These results are tempered by the reliance on self-report for many of the variables ascertained. Conclusion: Cannabis can frequently have negative Effects in its users, which can be amplified by certain demographic and/or psychosocial factors. Thus, users with a specific profile may be at a higher risk of unpleasant Effects from Cannabis use and caution should be noted when Cannabis is administered to young people for medicinal purposes.
