Cannabis and psychosis: an update on course and biological plausible mechanisms

Does cannabis affect cognitive functioning in patients with schizophrenia?

Introduction

Cannabis use impairs cognitive performance in healthy subjects; several studies have shown improved cognitive outcomes in schizophrenic patients using cannabis. The aim of this study was to evaluate the effects of cannabis use on cognitive function in Moroccan patients with schizophrenia who were cannabis users.

Method

Two groups were recruited in a Moroccan University Psychiatric Centre. Fifty patients diagnosed with schizophrenia according to the DSM-V who were cannabis users (SZ CANN +) and forty-nine patients diagnosed with schizophrenia according to DSM-V who do not use cannabis (SZ CANN-). Cognitive functioning was assessed using the CogState neuropsychological battery.

Results

The results of the study suggest that SZ CANN- patients performed better in the test of psychomotor function, attention and verbal memory. While SZ CANN+ patients performed better in the test of working memory, visual memory and emotional recognition. We found no relationship between SZ CANN+ patients and SZ CANN- patients concerning executive function.

Conclusions

Our results suggest that cannabis use may have different effects on neurocognitive functioning. It is associated with disorders of psychomotor function, attention and verbal memory. So, it is associated with an improvement in working memory, visual memory and emotion recognition.

Different effects of prenatal MAM vs. perinatal THC exposure on regional cerebral blood perfusion detected by Arterial Spin Labelling MRI in rats

Clinical studies consistently report structural impairments (i.e.: ventricular enlargement, decreased volume of anterior cingulate cortex or hippocampus) and functional abnormalities including changes in regional cerebral blood flow in individuals suffering from schizophrenia, which can be evaluated by magnetic resonance imaging (MRI) techniques. The aim of this study was to assess cerebral blood perfusion in several schizophrenia-related brain regions using Arterial Spin Labelling MRI (ASL MRI, 9.4 T Bruker BioSpec 94/30USR scanner) in rats. In this study, prenatal exposure to methylazoxymethanol acetate (MAM, 22 mg/kg) at gestational day (GD) 17 and the perinatal treatment with Δ-9-tetrahydrocannabinol (THC, 5 mg/kg) from GD15 to postnatal day 9 elicited behavioral deficits consistent with schizophrenia-like phenotype, which is in agreement with the neurodevelopmental hypothesis of schizophrenia. In MAM exposed rats a significant enlargement of lateral ventricles and perfusion changes (i.e.: increased blood perfusion in the circle of Willis and sensorimotor cortex and decreased perfusion in hippocampus) were detected. On the other hand, the THC perinatally exposed rats did not show differences in the cerebral blood perfusion in any region of interest. These results suggest that although both pre/perinatal insults showed some of the schizophrenia-like deficits, these are not strictly related to distinct hemodynamic features.

The role of cannabinoids in pain control: the good, the bad, and the ugly

Cannabinoids appear to possess many potential medical uses, which may extend to pain control. A narrative review of the literature has found a variety of studies testing botanical and synthetic cannabinoids in different pain syndromes (acute pain, cancer pain, chronic noncancer pain, fibromyalgia pain, migraine, neuropathic pain, visceral pain, and others). Results from these studies are mixed; cannabinoids appear to be most effective in controlling neuropathic pain, allodynia, medication-rebound headache, and chronic noncancer pain, but do not seem to offer any advantage over nonopioid analgesics for acute pain. Cannabinoids seem to work no better than placebo for visceral pain and conferred only modest analgesic effect in cancer pain. Cannabinoids do many good things - they appear to be effective in treating certain types of pain without the issues of tolerance associated with opioids. Negatively, marijuana currently has a very murky legal status all over the world - laws regulating its use are inconsistent and in flux. Thus, both patients and prescribers may be unsure about whether or not it is an appropriate form of pain control. Cannabinoid-based analgesia has been linked to potential memory deficits and cognitive impairment. A great deal more remains to be elucidated about cannabinoids which may emerge to play an important role in the treatment of neuropathic and possibly other painful conditions. There remains a great deal more to learn about the role of cannabinoids in pain management.

Cannabis and psychosis: the impact of polydrug use

Purpose

While research has consistently identified an association between cannabis use and psychosis, few studies have examined this relationship in a polydrug context (i.e. combining cannabis with other illicit substances). The paper aims to discuss this issue.

Design/methodology/approach

The present study sought to examine the association between recreational drug use (cannabis only vs polydrug) and psychotic disorders. Analysis was conducted on a large, representative survey of young Danish people aged 24 (n=4,718). Participants completed self-report measures of lifetime drug use and this information was linked to the Danish psychiatric registry system.

Findings

Multivariate binary logistic regression analysis was used to examine the association between drug use (no drug use, cannabis only, cannabis and other drug) and ICD-10 psychotic disorders, while controlling for gender and parental history of psychosis. Compared with no drug use, the use of cannabis only did not increase the risk of psychosis while the odds ratio for cannabis and other drug were statistically significant.

Research limitations/implications

Psychosis risk may be associated with the cumulative effect of polydrug use.

Practical implications

Cannabis use may be a proxy for other drug use in research studies.

Originality/value

This study is innovative as it uses linked self-report and administrative data for a large sample. Administrative data were used to as an objective mental health status indicator.

Gene × Environment Interactions in Schizophrenia: Evidence from Genetic Mouse Models

The study of gene × environment, as well as epistatic interactions in schizophrenia, has provided important insight into the complex etiopathologic basis of schizophrenia. It has also increased our understanding of the role of susceptibility genes in the disorder and is an important consideration as we seek to translate genetic advances into novel antipsychotic treatment targets. This review summarises data arising from research involving the modelling of gene × environment interactions in schizophrenia using preclinical genetic models. Evidence for synergistic effects on the expression of schizophrenia-relevant endophenotypes will be discussed. It is proposed that valid and multifactorial preclinical models are important tools for identifying critical areas, as well as underlying mechanisms, of convergence of genetic and environmental risk factors, and their interaction in schizophrenia.

Pathways to psychosis in cannabis abuse

Cannabis has been implicated as a risk factor for the development of schizophrenia, but the exact biological mechanisms remain unclear. In this review, we attempt to understand the neurobiological pathways that link cannabis use to schizophrenia. This has been an area of great debate; despite similarities between cannabis users and schizophrenia patients, the evidence is not sufficient to establish cause-and-effect. There have been advances in the understanding of the mechanisms of cannabis dependence as well as the role of the cannabinoid system in the development of psychosis and schizophrenia. The neurobiological mechanisms associated with the development of psychosis and effects from cannabis use may be similar but remain elusive. In order to better understand these associations, this paper will show common neurobiological and neuroanatomical changes as well as common cognitive dysfunction in cannabis users and patients of schizophrenia. We conclude that epidemiologic evidence highlights potential causal links; however, neurobiological evidence for causality remains weak.

The rapidly increasing trend of cannabis use in burn injury

The use of cannabis is currently increasing according to U.S. Department of Health and Human Services (HHS). Surprisingly, cannabis use among burn patients is poorly reported in literature. In this study, rates of cannabis use in burn patients are compared with general population. Data from the National Burn Repository (NBR) were used to investigate incidence, demographics, and outcomes in relation to use of cannabis as evidenced by urine drug screen (UDS). Thousands of patients from the NBR from 2002 to 2011 were included in this retrospective study. Inclusion criteria were patients older than 12 years of age who received a drug screen. Data points analyzed were patients' age, sex, UDS status, mechanism of burn injury, total body surface area, length of stay, ICU days, and insurance characteristics. Incidence of cannabis use in burn patients from the NBR was compared against national general population rates (gathered by Health and Human Services) using chi-square tests. Additionally, the burn patient population was analyzed using bivariate analysis and t-tests to find differences in the characteristics of these patients as well as differences in outcomes. Seventeen thousand eighty out of over 112,000 patients from NBR had information available for UDS. The incidence of cannabis use is increasing among the general population, but the rate is increasing more quickly among patients in the burn patient population (P = .0022). In 2002, 6.0% of patients in burn units had cannabis+ UDS, which was comparable with national incidence of 6.2%. By 2011, 27.0% of burn patients tested cannabis+ while national incidence of cannabis use was 7.0%. Patients who test cannabis+ are generally men (80.1%, P < .0001) and are younger on average (35 years old vs 42, P < .0001). The most common mechanisms of injury among patients who test cannabis+ or cannabis- are similar. Flame injury makes up >60% of injuries, followed by scalds that are >15%. In comparing cannabis+/- patients, cannabis+ patients are more likely to be uninsured (25.2% vs 17.26%, P < .0001). Finally, patients who test cannabis+ have larger burns (TBSA% of 12.94 vs 10.98, P < .0001), have a longer length of stay (13.31 days vs 12.6, P = .16), spend more days in the ICU (7.84 vs 6.39, P = .0006), and have more operations (2.78 vs 2.05, P < .0001). The rate patients testing positive for cannabis in burn units is growing quickly. These patients are younger and are less likely to be insured. These patients also have larger burns, spend more time in ICUs, and have a greater number of operations. The increasing use of cannabis, as expected from legalization of cannabis in multiple states, among burn patient population may lead to increased burden on already tenuous health care resources.

Cannabis use in early adolescence: Evidence of amygdala hypersensitivity to signals of threat

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Teenagers experimenting with cannabis may be characterized with fMRI.

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We report a face processing study of cannabis experimenting teenagers.

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Cannabis experimenting teenagers exhibit greater amygdala reactivity to angry faces.

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Very low use of cannabis during adolescence may impact healthy emotional development.

Cannabis use in adolescence may be characterized by differences in the neural basis of affective processing. In this study, we used an fMRI affective face processing task to compare a large group (n = 70) of 14-year olds with a history of cannabis use to a group (n = 70) of never-using controls matched on numerous characteristics including IQ, SES, alcohol and cigarette use. The task contained short movies displaying angry and neutral faces. Results indicated that cannabis users had greater reactivity in the bilateral amygdalae to angry faces than neutral faces, an effect that was not observed in their abstinent peers. In contrast, activity levels in the cannabis users in cortical areas including the right temporal-parietal junction and bilateral dorsolateral prefrontal cortex did not discriminate between the two face conditions, but did differ in controls. Results did not change after excluding subjects with any psychiatric symptomology. Given the high density of cannabinoid receptors in the amygdala, our findings suggest cannabis use in early adolescence is associated with hypersensitivity to signals of threat. Hypersensitivity to negative affect in adolescence may place the subject at-risk for mood disorders in adulthood.

Mismatch negativity in tobacco-naïve cannabis users and its alteration with acute nicotine administration

Chronic cannabis use may interact with factors, such as age of onset of cannabis use, family history, and genetic factors, to elicit schizophrenia (SZ)-like symptoms, including sensory and cognitive deficits. However, evidence of a relationship between cannabis use and cognitive impairment is confounded by concomitant use of tobacco. The objective of this study was to compare tobacco-naïve cannabis users with individuals without a history of tobacco/cannabis use on the auditory mismatch negativity (MMN) event-related potential (ERP), a neural measure of auditory deviance detection which is diminished in SZ. An exploratory arm of the study, conducted within a randomized, double-blind, placebo controlled design, examined the acute effects of nicotine gum (6mg) on MMN in cannabis users. MMN was recorded in response to 5 deviant stimuli within an optimal MMN paradigm in 44 healthy, non-tobacco smoking volunteers aged 18-26. Cannabis users (n=21) started smoking cannabis prior to age 17, at least 1 joint per month. To examine the effects of chronicity, users were grouped into relatively heavy long-term (HLT; n=11) users and light short-term (LST; n=10) users. Impaired deviance detection was shown in cannabis users vs. nonusers as reflected by a smaller MMN to duration deviants. Chronicity of use was also associated with MMN alterations, as HLTs displayed a reduced duration and gap MMN vs. LSTs. Compared with placebo, nicotine treatment enhanced select MMN deviants in cannabis user subgroups. As deficits associated with early and persistent cannabis use are similar to those seen in SZ, these dose-dependant disturbances in early sensory processing with cannabis use may be one cognitive pathway which mediates an increased risk for SZ in vulnerable youth, and be influenced by concurrent cigarette smoking behavior.

Quality of life and risk of psychiatric disorders among regular users of alcohol, nicotine, and cannabis: An analysis of the National Epidemiological Survey on Alcohol and Related Conditions (NESARC)

Research is limited on the effects of regular substance use on mental health-related outcomes. We used a large nationally representative survey to examine current and future quality of life and risk of psychiatric disorders among past-year regular (weekly) users of alcohol, nicotine, and cannabis. Data on psychiatric disorders and quality of life from two waves (Wave 1 N = 43,093, Wave 2 N = 34,653) of the National Epidemiological Survey on Alcohol and Related Conditions (NESARC) were used to test study aims. In cross-sectional analyses, regular nicotine and cannabis use were associated with higher rates of psychiatric disorder, though regular alcohol use was associated with lower rates of disorders. Prospective analyses found that regular nicotine use predicted onset of anxiety, depressive, and bipolar disorders. Regular alcohol use predicted lower risk of these disorders. Regular cannabis use uniquely predicted the development of bipolar disorder, panic disorder with agoraphobia, and social phobia. Lastly, regular alcohol use predicted improvements in physical and mental health-related quality of life, whereas nicotine predicted deterioration in these outcomes. Regular cannabis use predicted declines in mental, but not physical health. These data add to the literature on the relations between substance use and mental and physical health and suggest increased risk of mental health problems among regular nicotine and cannabis users and better mental and physical health among regular alcohol users. Examination of mechanisms underlying these relationships is needed.

Genetic dissection of the psychotomimetic effects of cannabinoid exposure

Cannabis use is an established risk factor for the development of schizophrenia and related psychotic disorders. Factors that may mediate susceptibility to the psychosis-inducing effects of cannabis include the age at onset of first cannabis use, genetic predisposition, as well as interaction with other environmental risk variables. Clinical and preclinical genetic studies provide increasing evidence that, in particular, genes encoding proteins implicated in dopamine signalling are implicated in the cannabis-psychosis association. In the present review, we focus on both human and animal studies which have focused on identifying the neuronal basis of these interactions. We conclude that further studies are required to provide greater mechanistic insight into the long-term and neurodevelopmental effects of cannabis use, with implications for improved understanding of the cannabis-psychosis relationship.

Cannabis and psychosis: Neurobiology

Cannabis is a known risk factor for schizophrenia, although the exact neurobiological process through which the effects on psychosis occur is not well-understood. In this review, we attempt to develop and discuss a possible pathway for the development of psychosis. We examine the neurobiological changes due to cannabis to see if these changes are similar to those seen in schizophrenic patients the findings show similarities; however, these mere similarities cannot establish a 'cause-effect' relationship as a number of people with similar changes do not develop schizophrenia. Therefore, the 'transition-to-psychosis' due to cannabis, despite being a strong risk factor, remains uncertain based upon neurobiological changes. It appears that other multiple factors might be involved in these processes which are beyond neurobiological factors. Major advances have been made in understanding the underpinning of marijuana dependence, and the role of the cannabinoid system, which is a major area for targeting medications to treat marijuana withdrawal and dependence, as well as other addictions is of now, it is clear that some of the similarities in the neurobiology of cannabis and schizophrenia may indicate a mechanism for the development of psychosis, but its trajectories are undetermined.

Comorbidity between hypomania and substance use disorders

BACKGROUND

Bipolar disorder is associated with substance use and misuse. However, to date few studies have examined the relationship between hypomania and substance misuse and dependence in the general population.

METHODS

Data come from the National Institute of Mental Health Collaborative Psychiatric Epidemiology Surveys (CPES), a set of multi-stage area probability samples of US adults (N=10,404). Multivariable linear and logistic regression was used to assess the relationship between DSM-IV hypomania and nicotine, alcohol, cannabis, cocaine, and prescription drug use. Models were adjusted for age, gender, education, and marital status. Stratified analyses and interaction terms were used to determine whether the relationship between hypomania and substance misuse varied by race/ethnicity.

RESULTS

The 12-month prevalence of hypomania was 0.5%. Hypomania was more common among African Americans (0.9%) relative to non-Hispanic Whites (0.5%) or other race/ethnicities (0.7%). Individuals with hypomania were 3.6 (95% CI: 1.5, 8.5) and 2.9 (95% CI: 1.3, 6.8) times more likely to also meet criteria for alcohol abuse/dependence and drug abuse/dependence relative to individuals without. The relationship between hypomania and substance use outcomes did not vary by race/ethnicity.

LIMITATIONS

The primary limitation of this study is its cross-sectional design, which precludes any inference about the causal nature of comorbid hypomania-substance use.

CONCLUSIONS

Hypomania is associated with increased likelihood of substance use and dependence/abuse across a broad range of substances. These associations were consistent across racial/ethnic groups. Findings indicate that even sub-syndromal conditions, such as hypomania, are significantly related to substance use and misuse in the community.

A case of self amputation of penis by cannabis induced psychosis

Self-mutilation, self-injuring or self-harming behaviour has been defined as deliberate destruction or alteration of body tissue in the absence of conscious suicidal intention. Persons suffering from mental disorder may inflict hundred of small wounds upon themselves which may be added to the actual cause of death. Another recognized syndrome is self mutilation of genitals almost invariably in males suffering from paranoid schizophrenia and often with strong religious flavour to their delusion. Here we present a case of a 35-year-old male who self mutilated his penis due to dependence on cannabis for the past few years that led to a condition called cannabis induced psychosis.

Bilateral testicular self-castration due to cannabis abuse: a case report

Introduction

The self-mutilating patient is an unusual psychiatric presentation in the emergency room. Nonetheless, serious underlying psychiatric pathology and drug abuse are important background risk factors. A careful stepwise approach in the emergency room is essential, although the prognosis, follow-up, and eventual rehabilitation can be problematic.

We present a unique and original case of bilateral self-castration caused by cannabis abuse.

Case Presentation

We report a case of a 40-year-old Berber man, who was presented to our emergency room with externalization of both testes using his long fingernails, associated with hemodynamic shock. After stabilization of his state, our patient was admitted to the operating room where hemostasis was achieved.

Conclusion

The clinical characteristics of self-mutilation are manifold and there is a lack of agreement about its etiology. The complex behavior associated with drug abuse may be one cause of self-mutilation. Dysfunction of the inhibitory brain circuitry caused by substance abuse could explain why this cannabis-addicted patient lost control and self-mutilated. To the best of our knowledge, this is the first case report which presents an association between self-castration and cannabis abuse.

The role of cannabinoids in modulating emotional and non-emotional memory processes in the hippocampus

Cannabinoid agonists generally have a disruptive effect on memory, learning, and operant behavior that is considered to be hippocampus-dependent. Nevertheless, under certain conditions, cannabinoid receptor activation may facilitate neuronal learning processes. For example, CB₁ receptors are essential for the extinction of conditioned fear associations, indicating an important role for this receptor in neuronal emotional learning and memory. This review examines the diverse effects of cannabinoids on hippocampal memory and plasticity. It shows how the effects of cannabinoid receptor activation may vary depending on the route of administration, the nature of the task (aversive or not), and whether it involves emotional memory formation (e.g., conditioned fear and extinction learning) or non-emotional memory formation (e.g., spatial learning). It also examines the memory stage under investigation (acquisition, consolidation, retrieval, extinction), and the brain areas involved. Differences between the effects of exogenous and endogenous agonists are also discussed. The apparently biphasic effects of cannabinoids on anxiety is noted as this implies that the effects of cannabinoid receptor agonists on hippocampal learning and memory may be attributable to a general modulation of anxiety or stress levels and not to memory per se. The review concludes that cannabinoids have diverse effects on hippocampal memory and plasticity that cannot be categorized simply into an impairing or an enhancing effect. A better understanding of the involvement of cannabinoids in memory processes will help determine whether the benefits of the clinical use of cannabinoids outweigh the risks of possible memory impairments.

Associations between substance use, neuropsychological functioning and treatment response in psychosis

Relationships between substance use, severity of psychosis, and neuropsychological functioning were examined, together with their associations with treatment response and retention status. Participants included 477 people with psychosis (354 volunteers registered on a research database, and 123 enrolled in a treatment trial for substance misuse). Variables of primary interest included substance use history, course of psychotic disorder, and neuropsychological functioning on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Specific RBANS deficits were associated with a more chronic illness course. Compared to those with a stable or chronic course, younger people with a single episode of psychosis were more likely to have uncertain diagnoses, higher levels of substance use problems and variable neuropsychological functioning. History of substance use was not associated with additional overall neuropsychological deficits. Likewise, treatment retention and outcome were not associated with neuropsychological functioning. The findings suggest that, among people with co-existing psychotic and substance use disorders, response to cognitive-behaviour therapy is likely to be independent of neuropsychological functioning. Consideration should also be given to the potential use of neuropsychological assessments to assist differentiation of likely substance-associated psychosis from primary psychosis.

Diffusion tensor imaging in the early phase of schizophrenia: what have we learned?

The dysconnectivity model suggests that disturbed integration of neural communication is central to schizophrenia. The integrity of macro-structural brain circuits can be examined with diffusion tensor imaging (DTI), an MRI application sensitive to microstructural abnormalities of brain white matter. DTI studies in first-episode schizophrenia patients and individuals at high-risk of psychosis can provide insight into the role of structural dysconnectivity in the liability, onset and early course of psychosis. This review discusses (i) views on the role of white matter abnormalities in schizophrenia, (ii) DTI and its application in schizophrenia, (iii) DTI findings in first-episode patients and subjects at high-risk of psychosis; their timing, anatomical location and early course, (iv) the hypothesized underlying pathological substrate and possible causes of DTI white matter alterations, including effects of adolescent cannabis use, and (v) some methodological issues and future recommendations. In summary, there is evidence that DTI abnormalities convey a liability for psychosis and additional abnormalities occur around onset of psychosis. However, findings in first-episode patients are less robust than in chronic patients, and progression of disturbances may occur in the early course of poor-outcome patients. In addition, acceleration of the normal aging process may occur. Adolescent cannabis use has specific effects on DTI measures. An unresolved issue is the underlying pathology of DTI abnormalities, and combining DTI with other MRI indices can provide more insight. More research is needed on which genetic and environmental factors play a role in the variability of current results.

Risk factors predicting onset and persistence of subthreshold expression of bipolar psychopathology among youth from the community

OBJECTIVE

To examine factors increasing the risk for onset and persistence of subthreshold mania and depression.

METHOD

In a prospective cohort community study, the association between risk factors [a family history of mood disorders, trauma, substance use, attention-deficit/hyperactivity disorder (ADHD) and temperamental/personality traits] and onset of manic/depressive symptoms was determined in 705 adolescents. The interaction between baseline risk factors and baseline symptoms in predicting 8-year follow-up symptoms was used to model the impact of risk factors on persistence.

RESULTS

Onset of manic symptoms was associated with cannabis use and novelty seeking (NS), but NS predicted a transitory course. Onset of depressive symptoms was associated with a family history of depression. ADHD and harm avoidance (HA) were associated with persistence of depressive symptoms, while trauma and a family history of depression predicted a transitory course.

CONCLUSION

Different risk factors may operate during onset and persistence of subthreshold mania and depression. The differential associations found for mania and depression dimensions suggest partly different underlying mechanisms.

Does dopamine mediate the psychosis-inducing effects of cannabis? A review and integration of findings across disciplines

General population epidemiological studies have consistently found that cannabis use increases the risk of developing psychotic disorders in a dose-dependent manner. While the epidemiological signal between cannabis and psychosis has gained considerable attention, the biological mechanism whereby cannabis increases risk for psychosis remains poorly understood. Animal research suggests that delta-9-tetrahydrocannabinol (THC, the main psychoactive component of cannabis) increases dopamine levels in several regions of the brain, including striatal and prefrontal areas. Since dopamine is hypothesized to represent a crucial common final pathway between brain biology and actual experience of psychosis, a focus on dopamine may initially be productive in the examination of the psychotomimetic effects of cannabis. Therefore, this review examines the evidence concerning the interactions between THC, endocannabinoids and dopamine in the cortical as well as subcortical regions implicated in psychosis, and considers possible mechanisms whereby cannabis-induced dopamine dysregulation may give rise to delusions and hallucinations. It is concluded that further study of the mechanisms underlying the link between cannabis and psychosis may be conducted productively from the perspective of progressive developmental sensitization, resulting from gene-environment interactions.

Substance use in adolescence and psychosis: clarifying the relationship

Adolescence is a time of exploration of the self, and this exploration may involve the use of alcohol and drugs. Sadly, for some, adolescence also marks the first signs of a psychosis. The temporal proximity between the onset of substance use and of psychosis has been the cause of much debate. Here we review the association of alcohol, cannabis, stimulants, and other drugs with psychosis, and we conclude that the use of cannabis and the amphetamines significantly contributes to the risk of psychosis.

Efeitos comportamentais, cognitivos e psicofisiológicos dos canabinoides: relevância para a psicose e a esquizofrenia

Avanços recentes no conhecimento sobre a função do receptor de canabinoide renovaram o interesse na associação entre cannabis e psicose. Linhas convergentes de evidências sugerem que os canabinoides podem produzir uma ampla gama de sintomas transitórios positivos, negativos e cognitivos assemelhados aos de esquizofrenia. Os canabinoides também produzem alguns déficits psicofisiológicos sabidamente presentes na esquizofrenia. É igualmente claro que em indivíduos com um transtorno psicótico estabelecido, os canabinoides podem exacerbar sintomas, desencadear recaídas e ter consequências negativas no curso da doença. Evidências crescentes sugerem que a exposição precoce e pesada à cannabis pode aumentar o risco de se desenvolver um transtorno psicótico como a esquizofrenia. A relação entre exposição à cannabis e esquizofrenia preenche alguns, mas não todos os critérios usuais de causalidade. Porém, a maioria das pessoas que utilizam cannabis não desenvolve esquizofrenia e muitas pessoas diagnosticadas com esquizofrenia nunca utilizaram cannabis. Portanto, é provável que a exposição à cannabis seja uma "causa componente" que interage com outros fatores para "causar" esquizofrenia ou outro transtorno psicótico, mas não é nem necessária nem suficiente para fazê-lo sozinha. No entanto, na ausência de causas conhecidas da esquizofrenia e com as implicações de políticas de saúde pública, se tal vínculo for estabelecido, as causas componentes, tais como a exposição a canabinoide, devem continuar sendo um foco de estudos futuros. Finalmente, são necessárias mais pesquisas para identificar os fatores subjacentes à vulnerabilidade à psicose relacionada a canabinoide e para elucidar os mecanismos biológicos subjacentes a esse risco.

Abuso de cannabis em pacientes com transtornos psiquiátricos: atualização para uma antiga evidência

OBJETIVO: Realizar uma atualização sobre o abuso de cannabis em pacientes com transtornos psiquiátricos. MÉTODO: Busca de artigos nas bases de dados eletrônicas Medline, The Cochrane Library Database, Lilacs, PubMed e SciELO, utilizando os descritores "marijuana abuse", "cannabis abuse", "psychiatric disorders" AND "mental disorders"; incluindo artigos que avaliaram ambas as exposições para abuso e dependência de cannabis e qualquer outro transtorno psiquiátrico. Foi considerado o período até dezembro de 2009. RESULTADOS: Observou-se que o abuso frequente de cannabis pode aumentar o risco para o desenvolvimento de esquizofrenia e de sintomas psicóticos crônicos, embora estes achados ainda careçam de comprovação. A cannabis parece ser uma das drogas de escolha de portadores de transtorno afetivo bipolar, sendo que é descrito que estados maníacos podem ser induzidos pelo seu consumo. O abuso de maconha também frequentemente co-ocorre em indivíduos com transtornos ansiosos, sendo que a relação de cronicidade destas condições e o consumo de maconha ainda é incerta. Para depressão ainda não existem evidências claras que apontem que o consumo de cannabis ocorre como forma de automedicação. Em indivíduos com transtornos psiquiátricos, há relatos de que o uso da cannabis pode exacerbar sintomas positivos, somar efeitos negativos no curso do transtorno, contribuir para pior adesão ao tratamento e levar a maior número de hospitalizações. CONCLUSÃO: O abuso de cannabis em pacientes com transtornos psiquiátricos como esquizofrenia, transtornos do humor e ansiosos tem impacto negativo tanto na fase aguda quanto em fases mais avançadas destas condições, embora futuros estudos avaliando estas associações ainda sejam necessários.

Adolescent cannabis use increases risk for cocaine-induced paranoia

Cannabis can produce and/or exacerbate psychotic symptoms in vulnerable individuals. Early exposure to cannabis, particularly in combination with genetic factors, increases the risk of a subsequent, primary, psychotic disorder. Because paranoia is a common feature of stimulant abuse and cocaine-dependent individuals frequently endorse a history of cannabis abuse, we examined whether early cannabis exposure, in conjunction with polymorphic variation in the catechol-O-methyl transferase gene (COMT Val158Met), influences the risk for cocaine-induced paranoia (CIP).

METHODS

Cannabis-use history was obtained in 1140 cocaine-dependent individuals from a family-based (affected sibling pair) study using the Semi-Structured Assessment for Drug Dependence and Alcoholism (SSADDA). Logistic regression and generalized estimating equations' analyses were used to examine the role of adolescent-onset cannabis use (< or =15 years of age) on CIP risk, both controlling for previously implicated CIP risk factors and familial relationships, and considering potential interactions with COMT Val158Met genotype.

RESULTS

Cocaine-dependent individuals who endorsed CIP had significantly higher rates of adolescent-onset cannabis use than those without CIP (62.2% vs. 50.2%; chi(2)=15.2, df=1, p<0.0001), a finding that remained after controlling for sibling correlations and other risk factors. There were no effects of COMT genotype or genotype by early cannabis onset interactions. A modest (OR=1.4) and nearly significant (p=0.053) effect of CIP status in probands on CIP status in siblings was also noted.

CONCLUSIONS

Adolescent-onset cannabis use increases the risk of CIP in cocaine-dependent individuals. COMT genotype and its interaction with early cannabis exposure did not emerge as significant predictors of CIP. In addition, trait vulnerability to CIP may also be familial in nature.

Subjective effects of cannabis before the first psychotic episode

OBJECTIVE

The aim of the present study was to gain more insight into the positive and negative effects of cannabis in the prodromal phase of schizophrenia and in the ultra-high-risk (UHR) state for psychosis.

METHOD

A theory-driven questionnaire was used to examine subjective effects in the prodromal phase in male subjects with a recent onset of schizophrenia or related disorder (n = 52) and in the UHR state in help-seeking male subjects screened for being at UHR for psychosis (n = 17); both groups were compared to cannabis-using controls from the general population (n=52).

RESULTS

Recent-onset patients and UHR subjects reported feeling more anxious, depressed and suspicious immediately after cannabis use. Some patients also reported feeling less depressed after cannabis use. Recent-onset patients reported increased visual and acoustic hallucinations, and confusion after cannabis use. Of the recent-onset patients 37% reported that their very first psychotic symptoms occurred during cannabis intoxication. Long-term effects of cannabis reported more often by both patient groups were depression, less control over thoughts and social problems.

CONCLUSIONS

These results suggest that schizophrenia patients in the prodromal phase and subjects at UHR for psychosis are more sensitive to some negative effects of cannabis, in particular psychotic effects, compared to cannabis users from the general population. Although limited by the retrospective design in the recent-onset patients, the present study adds qualitative evidence to longitudinal studies that suggest that cannabis is a component cause in the onset of the first psychotic episode. Further studies are needed on the objective and subjective effects of cannabis in UHR subjects.

The role of cannabis in cognitive functioning of patients with schizophrenia

RATIONALE

Cognitive deficits are commonly found both in patients with schizophrenia (SCH) and in people with cannabis use disorders (CUD). Surprisingly, some small recent studies reported better cognitive performance in SCH patients with comorbid cannabis use disorders (SCH + CUD) compared to other SCH patients.

OBJECTIVES

The aim of the present study was to investigate the residual impact of CUD and specific patterns of consumption on cognition in a larger sample of SCH + CUD patients.

METHODS

We administered a cognitive test battery to 34 SCH and 35 currently abstinent SCH + CUD patients. We explored the association between patterns of cannabis consumption and cognitive performance. Potential confounds with influence on cognitive ability were assessed and controlled for.

RESULTS

SCH + CUD patients had poorer academic achievements and lower vocabulary scores, but they performed better in tests of verbal and working memory, visuomotor speed and executive function (p < .05). More frequent cannabis use was associated with better performance in attention and working memory tasks.

CONCLUSIONS

Although our findings might be interpreted as beneficial effect of cannabis use on cognition in patients with schizophrenia, we favorise an alternative interpretation: in our view, the better cognitive functioning of SCH + CUD patients may rather reflect a relatively lower vulnerability to psychosis compared to the SCH group. Lower vulnerability may correspond to a higher level of functioning such as cognitive ability. This conclusion is consistent with the view of cannabis playing a critical role in the manifestation of psychosis in at least some of the SCH + CUD patients.

Marijuana effectiveness as an HIV self-care strategy

Persons living with HIV/AIDS use self-care for symptom management. This study assesses the use of marijuana as a symptom management approach for six common symptoms for persons living with HIV/AIDS--anxiety, depression, fatigue, diarrhea, nausea, and peripheral neuropathy. This sub-analysis of the efficacy of a symptom management manual encompasses the experiences of participants from sites in the U.S., Africa, and Puerto Rico. Baseline data are analyzed to examine differences in the use and efficacy of marijuana as compared with prescribed and over-the-counter medications as well as the impact on adherence and quality of life.

Candidate genes for cannabis use disorders: findings, challenges and directions

AIM

Twin studies have shown that cannabis use disorders (abuse/dependence) are highly heritable. This review aims to: (i) review existing linkage studies of cannabis use disorders and (ii) review gene association studies, to identify potential candidate genes, including those that have been tested for composite substance use disorders and (iii) to highlight challenges in the genomic study of cannabis use disorders.

METHODS

Peer-reviewed linkage and candidate gene association studies are reviewed.

RESULTS

Four linkage studies are reviewed: results from these have homed in on regions on chromosomes 1, 3, 4, 9, 14, 17 and 18, which harbor candidates of predicted biological relevance, such as monoglyceride lipase (MGLL) on chromosome 3, but also novel genes, including ELTD1[epidermal growth factor (EGF), latrophilin and seven transmembrane domain containing 1] on chromosome 1. Gene association studies are presented for (a) genes posited to have specific influences on cannabis use disorders: CNR1, CB2, FAAH, MGLL, TRPV1 and GPR55 and (b) genes from various neurotransmitter systems that are likely to exert a non-specific influence on risk of cannabis use disorders, e.g. GABRA2, DRD2 and OPRM1.

CONCLUSIONS

There are challenges associated with (i) understanding biological complexity underlying cannabis use disorders (including the need to study gene-gene and gene-environment interactions), (ii) using diagnostic versus quantitative phenotypes, (iii) delineating which stage of cannabis involvement (e.g. use versus misuse) genes influence and (iv) problems of sample ascertainment.

Long-term effects of adolescent marijuana use prevention on adult mental health services utilization: the midwestern prevention project

Evaluated were effects of a drug abuse(1) prevention program, previously shown to prevent marijuana use in adolescence, on adulthood mental health service use. Analyses were conducted on 961 6th (41%) and 7th (59%) grade participants randomly assigned to intervention or control groups at baseline in 1984. These participants were followed-up through 2003 representing 15 waves of data collection. Eighty-five percent of participants were Caucasian and 56% were female. The hypothesis was that direct program effects on early adulthood mental health service use would be mediated by program effects on high school marijuana use trajectories. Structural equation models, imputing for missing data, demonstrated that MPP (Midwestern Prevention Project) program effects on mental health were mediated by the marijuana use growth curve intercept. Findings support the role of early adolescent drug use prevention programs in impacting later mental health problems. The study's limitations are noted.

The effect of cannabis on the brain: can it cause brain anomalies that lead to increased risk for schizophrenia?

PURPOSE OF REVIEW

This review explores what is known about the association of cannabis with schizophrenia, its effects on the brain, and whether the brain changes known to be present in schizophrenia could be caused by cannabis and thus lead to a psychosis.

RECENT FINDINGS

The heavy use of cannabis is known to be associated with some adverse consequences, such as the occurrence of acute psychotic episodes and the development of chronic schizophrenia in some people even after its use has terminated. Recent studies have produced controversy about whether cannabis in heavy use can cause irreversible brain damage, particularly to adolescents, and thus whether a chronic psychosis could be a result of brain changes caused by cannabis.

SUMMARY

From the evidence that exists, it appears that the above view is unlikely and that cannabis may even have benign effects on brain structure, not producing deleterious damage. Its neurochemical interactions with the dopaminergic pathway, however, may, particularly in genetically vulnerable individuals, have adverse consequences.

Doppeldiagnose Psychose und Sucht - Grundlagen und Therapie

Zusammenfassung: Patienten mit der Doppeldiagnose Psychose und Sucht (DD-Patienten) sind keine Randgruppe, sondern eine große und schwer behandelbare Kerngruppe unter den Patienten mit Schizophrenie. Vor allem unter Patienten im jugendlichen und jungen Erwachsenenalter steht der Missbrauch von Cannabis an erster Stelle. Unter den verschiedenen Erklärungsmodellen für die hohe Prävalenz der Komorbidität werden derzeit das Modell einer Induktion der Psychose durch den Cannabiskonsum bei primär erhöhter Vulnerabilität für Psychosen sowie das Modell gemeinsamer Vulnerabilitätsfaktoren für beide Störungen favorisiert. Die DD-Patienten haben überwiegend eine schlechte Compliance und einen ungünstigen langfristigen Verlauf ihrer Psychose mit häufigeren Rezidiven und stationären Aufenthalten. Im Sinne einer effizienteren Behandlung dieser Patientengruppe ist es erforderlich Ansätze aus der psychiatrischen Krankenversorgung und der Suchttherapie zu integrieren und aufeinander anzupassen. Die erfolgreichsten Therapiemodelle bieten die Behandlung beider Störungen zeitlich parallel und integriert in einem Setting. Sie haben in der Regel ihren Schwerpunkt im ambulanten Sektor, bieten Pharmakotherapie, Motivationsstärkung, Psychoedukation, kognitiv-verhaltenstherapeutische Ansätze und Familieninterventionen an, und sie können alltagsrelevante Besserungen der sozialen Anpassung und Reduktionen des Konsums erzielen.

Drug-associated psychoses and criminal responsibility

At present, the law draws a distinction when assigning criminal responsibility to those who commit offences while experiencing psychotic symptoms: if the symptoms are believed to arise because of ingesting drugs (an external cause), the offender is generally convicted of the offence; if the symptoms arise from a mental illness (an internal cause), the offender may be afforded a defence of insanity. In practice, drawing such a distinction can be problematic. There are difficulties for example in determining criminal responsibility when the use of drugs is followed by the emergence of a psychotic illness process that then continues to have an independent existence even in the absence of the ongoing substance use. This article analyses legal, policy, and expert witness perspectives relating to liberal, conservative, and intermediate approaches to this problematic area of jurisprudence.

Quality of web-based information on cannabis addiction

This study evaluated the quality of Web-based information on cannabis use and addiction and investigated particular content quality indicators. Three keywords ("cannabis addiction," "cannabis dependence," and "cannabis abuse") were entered into two popular World Wide Web search engines. Websites were assessed with a standardized proforma designed to rate sites on the basis of accountability, presentation, interactivity, readability, and content quality. "Health on the Net" (HON) quality label, and DISCERN scale scores were used to verify their efficiency as quality indicators. Of the 94 Websites identified, 57 were included. Most were commercial sites. Based on outcome measures, the overall quality of the sites turned out to be poor. A global score (the sum of accountability, interactivity, content quality and esthetic criteria) appeared as a good content quality indicator. While cannabis education Websites for patients are widespread, their global quality is poor. There is a need for better evidence-based information about cannabis use and addiction on the Web.

Treatment of patients comorbid for addiction and other psychiatric disorders

Psychiatric disorders and drug and alcohol use disorders commonly co-occur. A growing literature has documented the epidemiology and effects on the course of illness of comorbid psychiatric and substance use disorders (SUDs). Advances in treatment of co-occurring illnesses have progressed more slowly. The current article reviews recent developments in the diagnosis and treatment of co-occurring psychiatric disorders and SUDs with particular focus on psychotic disorders, affective disorders, anxiety disorders, personality disorders, and attention-deficit/hyperactivity disorder. Current treatment options and implications for future research are highlighted.