Subjective effects of cannabis before the first psychotic episode

Assessing evidence supporting cannabis harm reduction practices for adolescents at clinical high-risk for psychosis: a review and clinical implementation tool

Cannabis use is consistently associated with both increased incidence of frank psychotic disorders and acute exacerbations of psychotic symptoms in healthy individuals and people with psychosis spectrum disorders. Although there is uncertainty around causality, cannabis use may be one of a few modifiable risk factors for conversion to psychotic disorders in individuals with Clinical High Risk for Psychosis (CHR-P) syndromes, characterized by functionally impairing and distressing subthreshold psychotic symptoms. To date, few recommendations beyond abstinence to reduce adverse psychiatric events associated with cannabis use have been made. This narrative review synthesizes existing scientific literature on cannabis' acute psychotomimetic effects and epidemiological associations with psychotic disorders in both CHR-P and healthy individuals to bridge the gap between scientific knowledge and practical mental health intervention. There is compelling evidence for cannabis acutely exacerbating psychotic symptoms in CHR-P, but its impact on conversion to psychotic disorder is unclear. Current evidence supports a harm reduction approach in reducing frequency of acute psychotic-like experiences, though whether such interventions decrease CHR-P individuals' risk of conversion to psychotic disorder remains unknown. Specific recommendations include reducing frequency of use, lowering delta-9-tetrahydrocannabinol content in favor of cannabidiol-only products, avoiding products with inconsistent potency like edibles, enhancing patient-provider communication about cannabis use and psychotic-like experiences, and utilizing a collaborative and individualized therapeutic approach. Despite uncertainty surrounding cannabis' causal association with psychotic disorders, cautious attempts to reduce acute psychosis risk may benefit CHR-P individuals uninterested in abstinence. Further research is needed to clarify practices associated with minimization of cannabis-related psychosis risk.

The association between reasons for first using cannabis, later pattern of use, and risk of first-episode psychosis: the EU-GEI case-control study

BACKGROUND

While cannabis use is a well-established risk factor for psychosis, little is known about any association between reasons for first using cannabis (RFUC) and later patterns of use and risk of psychosis.

METHODS

We used data from 11 sites of the multicentre European Gene-Environment Interaction (EU-GEI) case-control study. 558 first-episode psychosis patients (FEPp) and 567 population controls who had used cannabis and reported their RFUC.We ran logistic regressions to examine whether RFUC were associated with first-episode psychosis (FEP) case-control status. Path analysis then examined the relationship between RFUC, subsequent patterns of cannabis use, and case-control status.

RESULTS

Controls (86.1%) and FEPp (75.63%) were most likely to report 'because of friends' as their most common RFUC. However, 20.1% of FEPp compared to 5.8% of controls reported: 'to feel better' as their RFUC (χ2 = 50.97; p < 0.001). RFUC 'to feel better' was associated with being a FEPp (OR 1.74; 95% CI 1.03-2.95) while RFUC 'with friends' was associated with being a control (OR 0.56; 95% CI 0.37-0.83). The path model indicated an association between RFUC 'to feel better' with heavy cannabis use and with FEPp-control status.

CONCLUSIONS

Both FEPp and controls usually started using cannabis with their friends, but more patients than controls had begun to use 'to feel better'. People who reported their reason for first using cannabis to 'feel better' were more likely to progress to heavy use and develop a psychotic disorder than those reporting 'because of friends'.

Consensus paper of the WFSBP task force on cannabis, cannabinoids and psychosis

OBJECTIVES

The liberalisation of cannabis laws, the increasing availability and potency of cannabis has renewed concern about the risk of psychosis with cannabis.

METHODS

The objective of the WFSBP task force was to review the literature about this relationship.

RESULTS

Converging lines of evidence suggest that exposure to cannabis increases the risk for psychoses ranging from transient psychotic states to chronic recurrent psychosis. The greater the dose, and the earlier the age of exposure, the greater the risk. For some psychosis outcomes, the evidence supports some of the criteria of causality. However, alternate explanations including reverse causality and confounders cannot be conclusively excluded. Furthermore, cannabis is neither necessary nor sufficient to cause psychosis. More likely it is one of the multiple causal components. In those with established psychosis, cannabis has a negative impact on the course and expression of the illness. Emerging evidence also suggests alterations in the endocannabinoid system in psychotic disorders.

CONCLUSIONS

Given that exposure to cannabis and cannabinoids is modifiable, delaying or eliminating exposure to cannabis or cannabinoids, could potentially impact the rates of psychosis related to cannabis, especially in those who are at high risk for developing the disorder.

Rates and correlates of cannabis-associated psychotic symptoms in over 230,000 people who use cannabis

Cannabis, a widely used psychoactive substance, can trigger acute cannabis-associated psychotic symptoms (CAPS) in people who use cannabis (PWUC). To assess rates and correlates of CAPS requiring emergency medical treatment, we analyzed data from an international sample of PWUC (n = 233,475). We found that 0.47% (95%CI 0.42; 0.52) PWUC reported lifetime occurrence of CAPS, defined as the occurrence of hallucinations and/or paranoia requiring emergency medical treatment following the use of cannabis. A range of factors correlated with risk of CAPS in the last year: higher rates were observed in young individuals [risk ratio (RR) 2.66, compared to older PWUC] and those residing in Denmark (RR 3.01, compared to PWUC from other countries). Furthermore, risk was elevated in those using predominantly high-potency resin (RR 2.11, compared to PWUC using herbal cannabis), those mixing cannabis with tobacco (RR 2.15, compared to PWUC not mixing with tobacco) and those with a diagnosis of psychosis (RR 14.01), bipolar (RR 4.30), anxiety (RR 2.92) and depression (RR 2.68), compared to individuals without a mental health diagnosis. Taken together, acute self-limiting psychotic symptoms in the context of cannabis use may occur in about 1 in 200 PWUC's lifetime. Some individuals could be particularly sensitive to the adverse psychological effects of cannabis, such as young individuals or those with pre-existing mental health vulnerabilities. In light of the movements towards legalization of recreational cannabis, more research should focus on the potential harms related to cannabis use, to educate PWUC and the public about risks related to its use.

Cannabis-induced dysphoria/paranoia mediates the link between childhood trauma and psychotic-like experiences in young cannabis users

Childhood trauma (abuse and neglect) is a major risk factor for cannabis use disorder and psychotic-spectrum disorders. Psychotic-like experiences (PLEs) in young people who use cannabis may be an early indicator of psychosis risk following cannabis use. We examined whether (i) childhood trauma moderates the association between cannabis use and PLEs, (ii) the association between childhood trauma and cannabis use is mediated by subjective effects of cannabis (euphoria and dysphoria/paranoia), and (iii) the association between childhood trauma and PLEs is also mediated by these subjective effects. Participants were 2630 cannabis users (aged 16-25) recruited online. They were asked to complete a cross-sectional survey measuring cannabis and other substance use, childhood trauma, PLEs, and the subjective effects of cannabis (euphoria and dysphoria/paranoia). A significant interaction indicated that the effect of cannabis on PLE frequency was stronger for individuals with more severe childhood trauma. Childhood trauma was also associated with greater cannabis use and PLE frequency, both of which were mediated by subjective dysphoria/paranoia when using the drug. This suggests childhood trauma is associated with greater PLEs in young people who use cannabis, which may be linked with an increased susceptibility to the dysphoric/paranoid subjective effects when using the drug. Childhood trauma should be addressed early in young people who use cannabis to mitigate the psychosis-associated harms of the drug.

Substance use in youth at-risk for serious mental illness

AIM

The aim of this paper is to describe the substance use of participants who are at-risk for serious mental illness (SMI).

METHOD

The Canadian Psychiatric Risk and Outcome study (PROCAN) is a two-site study of 243 youth and young adults aged 13 to 25 years, categorized into four groups: healthy controls (n = 42), stage 0 (asymptomatic individuals with risk of SMI typically family high risk; n = 41), stage 1a (distress disorder or mild symptoms of anxiety or depression; n = 53) and stage 1b (attenuated syndromes, including bipolar disorder or psychosis; n = 107). Substance use measures were administered at baseline, 6- and 12-months.

RESULTS

At baseline, the most commonly reported substance used in the past month was alcohol (43.6%), followed by cannabis (14.4%) and tobacco (12.4%). There were no significant group differences in use. 42.4% of all participants reported ever using cannabis in their lifetime, whereas 21.4% reported currently using cannabis. There were no group differences in ever having used cannabis. Regarding lifetime substance abuse disorders, cannabis use disorder (5.7%) and alcohol use disorder (4.5%) were the most common and more often reported in stage 1b participants relative to other groups. Furthermore, alcohol, cannabis and tobacco use remained relatively consistent at 6- and 12-month follow-ups when compared to baseline use.

CONCLUSION

Alcohol was the most commonly used substance followed by cannabis and tobacco. Although substance use did not differ between those at different stages of risk, overall prevention strategies are still warranted for youth at-risk for SMI, especially those who are more symptomatic and potentially at greater risk of developing an SMI.

Comorbid Cannabis and Tobacco Use Disorders in Hospitalized Patients with Psychotic-Spectrum Disorders

OBJECTIVE

Individuals with psychotic-spectrum disorders use tobacco and cannabis at higher rates than the general population and individuals with other psychiatric disorders, which may contribute to increased rates of medical problems and mortality. The present study examined whether individuals with psychosis and comorbid tobacco and/or cannabis use disorders exhibit differing clinical characteristics in terms of their sociodemographic, mental health, substance use, physical health, and medication use patterns. Elucidation of these profiles, and determining their relative severity, has important implications for treatment, including offering more targeted interventions based on type of comorbidity pattern.

METHODS

We examined the electronic medical records of 829 patients with psychotic-spectrum disorders admitted to a psychiatric hospital and categorized them as having: (1) cannabis use disorder (CUD); (2) tobacco use disorder (TUD); (3) comorbid cannabis and tobacco use disorders (CUD + TUD); or (4) neither disorder (no CUD/TUD). Multinomial logistic regression was used to compare the aforementioned groups on multiple variables controlling for age and sex.

RESULTS

Alcohol and stimulant use disorder diagnoses were each related to higher odds of having a CUD and CUD + TUD, relative to no CUD/TUD. Stimulant and polysubstance use disorder diagnoses were each related to higher odds of having a TUD compared to no CUD/TUD. Greater number of prescribed psychotropic medications was related to higher odds of a TUD compared to no CUD/TUD.

CONCLUSIONS

Although several differences between groups were accounted for by age of cannabis versus tobacco users, findings point to the importance of considering comorbid alcohol and substance use disorders among those with psychosis and CUD/TUD, as these comorbidities have important implications for screening and treatment selection during and following acute hospitalization.

Development and validation of the cannabis experiences questionnaire - Intoxication effects checklist (CEQ-I) short form

OBJECTIVE

To develop and validate a short form of the Cannabis Experiences Questionnaire - Intoxication Effects (CEQ-I), a 42-item scale which measures the euphoric and paranoid-dysphoric effects of cannabis intoxication.

METHOD

Exploratory and confirmatory factor analyses were conducted among 604 past-month cannabis users to develop the short form. The factor structure was replicated in a second sample of 146 past-month cannabis users. The concurrent validity of the scale was also examined.

RESULTS

Consistent with previous research, two factors were identified (paranoid-dysphoric; euphoric), and were replicated with confirmatory factor analyses. The most parsimonious scale consisted of 13 items. Correlations of short-form subscales with corresponding original subscales were high. The paranoid-dysphoric subscale was also moderately positively correlated with measures of psychotic-like experiences (PLEs) and psychological distress.

CONCLUSIONS

The revised and validated CEQ-I short form can be used to explore the euphoric and paranoid-dysphoric effects of cannabis intoxication in young cannabis users, and whether these experiences increase their risk of developing cannabis use and psychotic disorders. The CEQ-I short form has the potential to aid in the identification of young cannabis users at risk of the paranoid-dysphoric effects of cannabis intoxication and may assist in the development of early intervention strategies targeting cannabis users with PLEs.

Motivational changes of cannabis use prior to and during the course of schizophrenia

BACKGROUND AND OBJECTIVES

We investigated subjective reasons/motivation for cannabis use in patients with schizophrenia (n = 51) compared to otherwise healthy cannabis users (n = 109). Moreover, we explored possible changes in the motivational patterns of both groups over time.

METHODS

A questionnaire was developed with six dimensions of motivations to use cannabis: affect regulation, relaxation, habit, structuring everyday life, creativity, and sociability. Participants filled out the instrument regarding their present and initial use of cannabis.

RESULTS

At the time of onset of consumption, groups only differed significantly in habit with higher ratings for patients with schizophrenia and cannabis use (SCH+CAN group) and in sociability with higher ratings for otherwise healthy users (CAN group). In respect of present use, the motivation to consume cannabis was significantly higher for affect regulation and structuring everyday life in the SCH+CAN group and for relaxation and sociability in the CAN group. With reference to time-based variations, the SCH+CAN group reported increased relevance of structuring everyday life over time. Furthermore, the CAN group reported increased importance of habit over time, whereas the SCH+CAN patients showed decreased ratings of habit over time.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Our findings must be considered preliminary because of the retrospective nature of the assessment. Nevertheless, the present study provides an indication of the time-dependent variation of cannabis-use motivation in schizophrenia, which may provide a better understanding of the functions of cannabis use within the population. Results argue for specific motivational based interventions for the group of schizophrenia patients with regular cannabis use. (Am J Addict 2017;26:122-128).

Gone to Pot - A Review of the Association between Cannabis and Psychosis

Cannabis is the most commonly used illicit drug worldwide, with ~5 million daily users worldwide. Emerging evidence supports a number of associations between cannabis and psychosis/psychotic disorders, including schizophrenia. These associations-based on case-studies, surveys, epidemiological studies, and experimental studies indicate that cannabinoids can produce acute, transient effects; acute, persistent effects; and delayed, persistent effects that recapitulate the psychopathology and psychophysiology seen in schizophrenia. Acute exposure to both cannabis and synthetic cannabinoids (Spice/K2) can produce a full range of transient psychotomimetic symptoms, cognitive deficits, and psychophysiological abnormalities that bear a striking resemblance to symptoms of schizophrenia. In individuals with an established psychotic disorder, cannabinoids can exacerbate symptoms, trigger relapse, and have negative consequences on the course of the illness. Several factors appear to moderate these associations, including family history, genetic factors, history of childhood abuse, and the age at onset of cannabis use. Exposure to cannabinoids in adolescence confers a higher risk for psychosis outcomes in later life and the risk is dose-related. Individuals with polymorphisms of COMT and AKT1 genes may be at increased risk for psychotic disorders in association with cannabinoids, as are individuals with a family history of psychotic disorders or a history of childhood trauma. The relationship between cannabis and schizophrenia fulfills many but not all of the standard criteria for causality, including temporality, biological gradient, biological plausibility, experimental evidence, consistency, and coherence. At the present time, the evidence indicates that cannabis may be a component cause in the emergence of psychosis, and this warrants serious consideration from the point of view of public health policy.

Do former substance users with psychosis differ in their symptoms or function from non-substance users? A systematic meta-analysis

OBJECTIVE

To compare the symptoms and function of patients with psychosis who have ceased using substances to those who have psychosis but do not have a history of substance use.

METHOD

The databases EMBASE, MEDLINE and PsycINFO were searched for peer-reviewed publications in English reporting the characteristics of patients with psychotic illness who had stopped using substances and those who had never used substances. The searches yielded 20 articles that met the inclusion criteria. Four key outcome variables - positive symptoms, negative symptoms, depression and global function - and four other outcome measures reported in five or more studies were examined using meta-analysis.

RESULTS

Former substance-using patients were significantly younger than non-substance-using patients and were more likely to be male, but did not differ in age at onset of psychosis or in their level of education. There were no significant differences between former substance users and non-substance users in ratings of positive symptoms, negative symptoms, depression or global function. Among first-episode patients there was a trend towards former substance users having less severe depressive symptoms than non-substance users. In contrast, among non-first-episode patients, former substance users had significantly more depressive symptoms than non-substance users. In studies rated as being of higher quality, former substance users had significantly less severe positive symptoms than non-substance users.

CONCLUSION

The absence of significant differences between the two groups suggests that a history of substance use is not a poor prognostic indicator for patients who are able to stop using substances.

Cannabis affects people differently: inter-subject variation in the psychotogenic effects of Δ9-tetrahydrocannabinol: a functional magnetic resonance imaging study with healthy volunteers

BACKGROUND

Cannabis can induce transient psychotic symptoms, but not all users experience these adverse effects. We compared the neural response to Δ9-tetrahydrocannabinol (THC) in healthy volunteers in whom the drug did or did not induce acute psychotic symptoms. Method In a double-blind, placebo-controlled, pseudorandomized design, 21 healthy men with minimal experience of cannabis were given either 10 mg THC or placebo, orally. Behavioural and functional magnetic resonance imaging measures were then recorded whilst they performed a go/no-go task.

RESULTS

The sample was subdivided on the basis of the Positive and Negative Syndrome Scale positive score following administration of THC into transiently psychotic (TP; n = 11) and non-psychotic (NP; n = 10) groups. During the THC condition, TP subjects made more frequent inhibition errors than the NP group and showed differential activation relative to the NP group in the left parahippocampal gyrus, the left and right middle temporal gyri and in the right cerebellum. In these regions, THC had opposite effects on activation relative to placebo in the two groups. The TP group also showed less activation than the NP group in the right middle temporal gyrus and cerebellum, independent of the effects of THC.

CONCLUSIONS

In this first demonstration of inter-subject variability in sensitivity to the psychotogenic effects of THC, we found that the presence of acute psychotic symptoms was associated with a differential effect of THC on activation in the ventral and medial temporal cortex and cerebellum, suggesting that these regions mediate the effects of the drug on psychotic symptoms.

Clinical and sociodemographic comparison of people at high-risk for psychosis and with first-episode psychosis

OBJECTIVE

To compare clinical and sociodemographic characteristics previously associated with psychosis, between individuals at high-risk for psychosis (HR) and patients experiencing a first episode psychosis (FEP), to achieve a better understanding of factors associated with psychosis.

METHOD

Cross-sectional comparison of 30 individuals at HR with 30 age-gender matched FEP, presenting to an early intervention service for psychosis. Participants were followed-up for 2 years to establish the proportion of HR who made the transition into FEP.

RESULTS

Both groups showed similar socio-clinical characteristics, including immigration status, employment history, marital status, family history of psychotic illness, self-harm and alcohol and drug use. The HR group had a lower level of education, higher burden of trauma, earlier onset of psychiatric symptoms and a longer delay in accessing specialised services. A younger onset of symptoms was associated with a longer delay in accessing services in both groups. After a 2 year follow-up, only three (10%) of the HR group made a transition into FEP.

CONCLUSION

The similarities observed between individuals at HR and those with FEP suggest that known variables associated with psychosis may be equally prevalent in people at HR who do not develop a psychotic disorder.

Transmembrane domain Nrg1 mutant mice show altered susceptibility to the neurobehavioural actions of repeated THC exposure in adolescence

Heavy cannabis abuse increases the risk of developing schizophrenia. Adolescents appear particularly vulnerable to the development of psychosis-like symptoms after cannabis use. To test whether the schizophrenia candidate gene neuregulin 1 (NRG1) modulates the effects of cannabinoids in adolescence, we tested male adolescent heterozygous transmembrane domain Nrg1 mutant (Nrg1 TM HET) mice and wild type-like littermates (WT) for their neurobehavioural response to repeated Δ(9)-tetrahydrocannabinol (THC, 10 mg/kg i.p. for 21 d starting on post-natal day 31). During treatment and 48 h after treatment withdrawal, we assessed several behavioural parameters relevant to schizophrenia. After behavioural testing we measured autoradiographic CB(1), 5-HT(2A) and NMDA receptor binding. The hyperlocomotor phenotype typical of Nrg1 mutants emerged after drug withdrawal and was more pronounced in vehicle than THC-treated Nrg1 TM HET mice. All mice were equally sensitive to THC-induced suppression of locomotion. However, mutant mice appeared protected against inhibiting effects of repeated THC on investigative social behaviours. Neither THC nor Nrg1 genotype altered prepulse inhibition. Repeated adolescent THC promoted differential effects on CB(1) and 5-HT(2A) receptor binding in the substantia nigra and insular cortex respectively, decreasing binding in WT while increasing it in Nrg1 TM HET mice. THC also selectively affected 5-HT(2A) receptor binding in several other regions in WT mice, whereas NMDA receptor binding was only affected in mutant mice. Overall, Nrg1 mutation does not appear to increase the induction of psychotomimetic symptoms by repeated adolescent THC exposure but may attenuate some of its actions on social behaviour and schizophrenia-relevant neurotransmitter receptor profiles.

Cannabis, a complex plant: different compounds and different effects on individuals

Cannabis is a complex plant, with major compounds such as delta-9-tetrahydrocannabinol and cannabidiol, which have opposing effects. The discovery of its compounds has led to the further discovery of an important neurotransmitter system called the endocannabinoid system. This system is widely distributed in the brain and in the body, and is considered to be responsible for numerous significant functions. There has been a recent and consistent worldwide increase in cannabis potency, with increasing associated health concerns. A number of epidemiological research projects have shown links between dose-related cannabis use and an increased risk of development of an enduring psychotic illness. However, it is also known that not everyone who uses cannabis is affected adversely in the same way. What makes someone more susceptible to its negative effects is not yet known, however there are some emerging vulnerability factors, ranging from certain genes to personality characteristics. In this article we first provide an overview of the biochemical basis of cannabis research by examining the different effects of the two main compounds of the plant and the endocannabinoid system, and then go on to review available information on the possible factors explaining variation of its effects upon different individuals.

Does giving up substance use work for patients with psychosis? A systematic meta-analysis

OBJECTIVE

To assess the extent to which ceasing the use of cannabis or other substances reduces the symptoms and social disability associated with psychotic illness.

METHODS

The electronic databases CINAHL, EMBASE, MEDLINE and PsycINFO were searched for peer-reviewed publications in English that report data about the characteristics of current and former substance-using patients diagnosed with psychotic illnesses. The searches yielded 328 articles, of which 23 studies met the inclusion criteria. Four key outcome variables; positive symptoms, negative symptoms, ratings of depression and global function, and five other measures of outcome that were reported in five or more studies were examined using meta-analysis.

RESULTS

Current substance-using patients were significantly younger than former substance-using patients (standardised mean difference (SMD) = -0.38), but did not differ in age at onset of psychosis, sex, level of education or marital status. Current substance users had higher scores on rating scales of positive symptoms (SMD = 0.29) and depression (SMD = 0.36), and lower scores on global function (SMD = -0.26) when compared with former substance users. There was a significant improvement in the ratings of positive symptoms, mood and global function among patients who stopped using substances during the first episode of psychosis, while improvements in the symptoms of patients with a more established psychotic illness did not reach statistical significance.

CONCLUSION

The results suggest that substance use contributes to both the symptoms and the burden of disability experienced by patients with psychosis. Patients in the early stages of psychotic illness should be informed about the benefits of giving up substances earlier, rather than later in the illness. Psychiatric services should regard the treatment of substance use as an integral part of the treatment of psychotic disorders.

Cannabis use and age at onset of symptoms in subjects at clinical high risk for psychosis

OBJECTIVE

Numerous studies have found a robust association between cannabis use and the onset of psychosis. Nevertheless, the relationship between cannabis use and the onset of early (or, in retrospect, prodromal) symptoms of psychosis remains unclear. The study focused on investigating the relationship between cannabis use and early and high-risk symptoms in subjects at clinical high risk for psychosis.

METHOD

Prospective multicenter, naturalistic field study with an 18-month follow-up period in 245 help-seeking individuals clinically at high risk. The Composite International Diagnostic Interview was used to assess their cannabis use. Age at onset of high risk or certain early symptoms was assessed retrospectively with the Interview for the Retrospective Assessment of the Onset of Schizophrenia.

RESULTS

Younger age at onset of cannabis use or a cannabis use disorder was significantly related to younger age at onset of six symptoms (0.33 < r(s) < 0.83, 0.004 < P < 0.001). Onset of cannabis use preceded symptoms in most participants.

CONCLUSION

Our results provide support that cannabis use plays an important role in the development of psychosis in vulnerable individuals. Cannabis use in early adolescence should be discouraged.

Cannabis use and psychosis: re-visiting the role of childhood trauma

BACKGROUND

Cannabis consumption continues to be identified as a causal agent in the onset and development of psychosis. However, recent findings have shown that the effect of cannabis on psychosis may be moderated by childhood traumatic experiences.

METHOD

Using hierarchical multivariate logistic analyses the current study examined both the independent effect of cannabis consumption on psychosis diagnosis and the combined effect of cannabis consumption and childhood sexual abuse on psychosis diagnosis using data from the Adult Psychiatric Morbidity Survey 2007 (n=7403).

RESULTS

Findings suggested that cannabis consumption was predictive of psychosis diagnosis in a bivariate model; however, when estimated within a multivariate model that included childhood sexual abuse, the effect of cannabis use was attenuated and was not statistically significant. The multivariate analysis revealed that those who had experienced non-consensual sex in childhood were over six times [odds ratio (OR) 6.10] more likely to have had a diagnosis of psychosis compared with those who had not experienced this trauma. There was also a significant interaction. Individuals with a history of non-consensual sexual experience and cannabis consumption were over seven times more likely (OR 7.84) to have been diagnosed with psychosis compared with those without these experiences; however, this finding must be interpreted with caution as it emerged within an overall analytical step which was non-significant.

CONCLUSIONS

Future studies examining the effect of cannabis consumption on psychosis should adjust analyses for childhood trauma. Childhood trauma may advance existing gene-environment conceptualisations of the cannabis-psychosis link.

What every adolescent needs to know: cannabis can cause psychosis

OBJECTIVE

Cannabis is a widely used substance that may be becoming more socially accepted, legally tolerated, and utilized by younger individuals. This review explores the relationship between cannabis and the onset of psychosis as well as the policy ramifications of current research.

METHOD

This article synthesizes published work that was considered by the author to be relevant to the discussion of cannabis and the onset of psychosis.

RESULTS

The evidence suggests that, along with other harms, cannabis is a significant risk factor in the etiology of psychosis. Adolescents are more vulnerable to using cannabis, and because of their stage of mental development, the cognitive effects are more pronounced. The mechanism for this change is thought to be neuro-chemical with a stronger effect in those with a diathesis for psychosis.

CONCLUSION

The risk that cannabis poses to adolescent health should not be neglected. Policy measures should use a multifaceted and strategic perspective in order to prevent adolescents from using this drug.