Assessing evidence for a causal link between cannabis and psychosis: A review of cohort studies

Cigarette, electronic cigarette, and marijuana use among young adults under policy changes in California

Introduction

Since 2016, California has implemented a series of policies, including prohibiting the sale of tobacco products and electronic cigarettes (e-cigarettes) to persons under 21, cigarette tax increase, and recreational marijuana legalization. The study aims to examine the use of cigarettes, e-cigarettes, and marijuana among young adults (ages 18-25) and their associations with other factors in the context of these policy changes.

Methods

We used the data from the California Health Interview Survey (CHIS) 2017-2018 to compare the rates of using cigarettes, e-cigarettes, and marijuana separately or any use of the three. Using CHIS 2018 data, weighted logistic regression models were used to examine associations of using cigarettes, e-cigarettes, and marijuana separately or any use of these products/substance with demo-socioeconomic factors, psychological distress, and use of each product/substances.

Results

Cigarette smoking remained flat while the use of e-cigarettes and marijuana escalated among young adults from 2017 to 2018. Using tobacco products increased the use of marijuana or vice versa among young adults. Severe psychological distress was significantly associated with cigarette use (adjusted odds ratio [AOR] = 4.06; 95% CI = 1.32, 12.55), marijuana use (AOR = 2.32; 95% CI = 1.10, 4.48), and any use (AOR = 4.11; 95% CI = 1.93, 8.77). Moderate psychological distress was also significantly associated with the use of these products/substance. Underage (ages 18-20) young adults had lower odds of using cigarettes than other young adults (ages 21-25).

Conclusions

Our findings highlight the importance of addressing the use of cigarettes, e-cigarettes, and marijuana simultaneously through policies to curtail tobacco and marijuana use among young adults.

A bibliometric analysis of the cannabis and cannabinoid research literature

Background

Cannabis refers to a plant in the family Cannabaceae, which has been used medically, recreationally, and industrially. The last two decades, in particular, have seen a large increase in the volume of literature on this topic. The present bibliometric analysis aims to capture the characteristics of scholarly journal publications on the topic of cannabis and cannabinoid research.

Methods

Searches were run on the Scopus database on April 02, 2021, as follows “(TITLE (cannabi* OR hashish OR marijuana OR marihuana)) AND ( LIMIT-TO ( DOCTYPE,"ar" ) OR LIMIT-TO ( DOCTYPE,"re" ) )”. Results were exported on the same day to prevent discrepancies between daily database updates. Only “article” and “review” publication types were included; no further search limits were applied. The “article” publication type includes publications featuring original research, whereas “review” includes reviews and conference papers. The following data were collected: number of publications (in total and per year), authors, and journals; open access status; publications per journal; journals publishing the highest volume of literature and their impact factors, language of publication; document type; publication country; author affiliations; funding sponsors; most highly cited publications; and most highly published authors. Trends in this subset of publications were identified and presented. Bibliometric networks were constructed using the software tool VOSviewer.

Results

A total of 29 802 publications (10 214 open access), published by 65 109 authors, were published in 5474 journals from 1829 to 2021. The greatest number of publications was published over the last 20 years. The journal that published the largest number of publications was Drug and Alcohol Dependence (n = 705). The most productive countries included the USA (n = 12 420), the UK (n = 2236), and Canada (n = 2062); many of the most common institutional affiliations and funding sponsors originated from these countries.

Conclusions

The number of publications published on the topic of cannabis follows an upward trend. Over the past 20 years, the volume of cannabis research has grown steeply, which can be attributed to a large amount of funding dedicated to researching this topic. Future research should continue to investigate changes in the publication characteristics of emerging research, as the volume of publications on this topic is expected to rapidly grow.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42238-022-00133-0.

Phytocannabinoids and schizophrenia: Focus on adolescence as a critical window of enhanced vulnerability and opportunity for treatment

The recent shift in socio-political debates and growing liberalization of Cannabis use across the globe has raised concern regarding its impact on vulnerable populations such as adolescents. Concurrent with declining perception of Cannabis harms, more adolescents are using it daily in several countries and consuming marijuana strains with high content of psychotropic delta (9)-tetrahydrocannabinol (THC). These dual, related trends seem to facilitate the development of compromised social and cognitive performance at adulthood, which are described in preclinical and human studies. Cannabis exerts its effects via altering signalling within the endocannabinoid system (ECS), which modulates the stress circuitry during the neurodevelopment. In this context early interventions appear to circumvent the emergence of adult neurodevelopmental deficits. Accordingly, Cannabis sativa second-most abundant compound, cannabidiol (CBD), emerges as a potential therapeutic agent to treat neuropsychiatric disorders. We first focus on human and preclinical studies on the long-term effects induced by adolescent THC exposure as a "critical window" of enhanced neurophysiological vulnerability, which could be involved in the pathophysiology of schizophrenia and related primary psychotic disorders. Then, we focus on adolescence as a "window of opportunity" for early pharmacological treatment, as novel risk reduction strategy for neurodevelopmental disorders. Thus, we review current preclinical and clinical evidence regarding the efficacy of CBD in terms of positive, negative and cognitive symptoms treatment, safety profile, and molecular targets.

General risks of harm with cannabinoids, cannabis, and cannabis-based medicine possibly relevant to patients receiving these for pain management: an overview of systematic reviews

ABSTRACT

The growing demand for improved pain treatments together with expanding legalization of, and access to, cannabinoids, cannabis, and cannabis-based medicines has intensified the focus on risk-benefit considerations in pain management. Given limited harms data from analgesic clinical trials, we conducted an overview of systematic reviews focused on all harms possibly relevant to patients receiving cannabinoids for pain management. This PROSPERO-registered, PRISMA-compliant systematic overview identified 79 reviews, encompassing over 2200 individual reports about psychiatric and psychosocial harms, cognitive/behavioral effects, motor vehicle accidents, cardiovascular, respiratory, cancer-related, maternal/fetal, and general harms. Reviews, and their included studies, were of variable quality. Available evidence suggests variable associations between cannabis exposure (ranging from monthly to daily use based largely on self-report) and psychosis, motor vehicle accidents, respiratory problems, and other harms. Most evidence comes from settings other than that of pain management (eg, nonmedicinal and experimental) but does signal a need for caution and more robust harms evaluation in future studies. Given partial overlap between patients receiving cannabinoids for pain management and individuals using cannabinoids for other reasons, lessons from the crisis of oversupply and overuse of opioids in some parts of the world emphasize the need to broadly consider harms evidence from real-world settings. The advancement of research on cannabinoid harms will serve to guide optimal approaches to the use of cannabinoids for pain management. In the meantime, this evidence should be carefully examined when making risk-benefit considerations about the use of cannabinoids, cannabis, and cannabis-based medicine for chronic pain.

Youth marijuana use: a review of causes and consequences

The legalization of medical and recreational marijuana has raised concerns about a potential increase in the availability and illegal use of marijuana by adolescent minors. To better understand the etiology, patterns, and consequences of adolescent marijuana use, this article reviews high quality, methodologically rigorous, longitudinal studies that focus on the role of personality factors such as sensation-seeking in the etiology of use, developmental trajectories of use and the effects of chronic use, potential gateway effects of marijuana on other illicit drugs, and its role in the onset of psychiatric disorders in adolescents and young adults. Implications are discussed in terms of mechanisms that account for initial and continued use of marijuana by adolescents, how use is associated with key developmental milestones and adult role socialization, and the potential of marijuana use during adolescence in furthering later drug involvement.

Risks and Protective Factors of the Prodromal Stage of Psychosis: A Literature Review

Psychosis is a syndrome characterized by features of reality distortion such as delusions and hallucinations. It may occur as a primary mental disorder or secondary to a medical or neurological illness or substance abuse. Several genetic, environmental, and protective risk factors have been identified and require further study. Neurobiological damage at the onset of schizophrenia is the most active and destructive. Therefore, it is important to detect the prodromal phase of psychosis so that interventions can be started early and the onset of psychosis delayed. Herein, we review the relevant epidemiological data on psychosis, particularly in Saudi Arabia. In addition, the risk and protective factors of psychosis will be discussed. Recent findings have shown that psychosis development is affected by genetic and environmental factors. Psychotic disorders are considered a cause of disability and are, therefore, a substantial economic burden. Consequently, it is important to try and detect the psychosis in its prodromal stage, where intervention may slow its progression and improve general wellbeing. Several tools have been identified to screen for the prodrome of psychosis, one of which is the prodromal questionnaire-brief version. This has been shown to be a promising tool that can be self-administered by the patient in contrast to long interview-based tools, which are time-consuming and require a physician to perform. Despite the limited evidence in the literature, there have been significant improvements in the outcomes of patients with psychosis when treated in the prodromal period. In summary, this article provides psychiatrists and researchers with an overview of psychosis, its risk factors, the prodromal stage of psychosis, tools to detect the prodromal phase, and potential treatments during this phase.

Prescribing medical cannabis: ethical considerations for primary care providers

Medical cannabis is widely available in the USA and legalisation is likely to expand. Despite the increased accessibility and use of medical cannabis, physicians have significant knowledge gaps regarding evidence of clinical benefits and potential harms. We argue that primary care providers have an ethical obligation to develop competency to provide cannabis to appropriate patients. Furthermore, specific ethical considerations should guide the recommendation of medical cannabis. In many cases, these ethical considerations are extensions of well-established principles of beneficence and nonmaleficence, which indicate that providers should recommend cannabis only for conditions that have the strongest evidence base. Additionally, the contested status of cannabis in American culture raises specific issues related to shared decision-making and patient education, as well as continuing clinical education.

Cannabis Use and the Risk for Psychosis and Affective Disorders

Objective: This review discusses the relationship between cannabis use and psychotic, bipolar, depressive, and anxiety disorders, as well as suicide. It summarizes epidemiological evidence from cross-sectional and long-term prospective studies and considers possible etiological mechanisms. Methods: Systematic reviews and methodologically robust studies in the field (from inception to February 2019) were identified using a comprehensive search of Medline, PsychINFO, and Embase and summarized using a narrative synthesis. Results: Consistent evidence, both from observational and experimental studies, has confirmed the important role of cannabis use in the initiation and persistence of psychotic disorders. The size of the effect is related to the extent of cannabis use, with greater risk for early cannabis use and use of high-potency varieties and synthetic cannabinoids. Accumulating evidence suggests that frequent cannabis use also increases the risk for mania as well as for suicide. However, the effect on depression is less clear and findings on anxiety are contradictory with only a few methodologically robust studies. Furthermore, the relationship with common mental disorders may involve reverse causality, as depression and anxiety are reported to lead to greater cannabis consumption in some studies. Pathogenetic mechanisms focus on the effect of tetrahydrocannabinol (THC, the main psychoactive ingredient of cannabis) interacting with genetic predisposition and perhaps other environmental risk factors. Cannabidiol (CBD), the other important ingredient of traditional cannabis, ameliorates the psychotogenic effects of THC but is absent from the high-potency varieties that are increasingly available. Conclusions: The evidence that heavy use of high-THC/low-CBD types of cannabis increases the risk of psychosis is sufficiently strong to merit public health education. Evidence of similar but smaller effects in mania and suicide is growing, but is not convincing for depression and anxiety. There is much current interest in the possibility that CBD may be therapeutically useful.

Cannabis Use Among Remote Indigenous Australians: Opportunities to Support Change Identified in Two Waves of Sampling

Background: Cannabis harms among Indigenous populations in Australia, New Zealand, Canada and the United States may be magnified by poorer health and heavy use. However, little direct evidence is available to evaluate cannabis' impacts. In communities in remote northern Queensland (Australia) where cannabis has become endemic, opportunities to support change were investigated. Methods: Opportunistically recruited participants (aged 15-49 years) discussed their cannabis use history in interviews in two waves of population sampling in Cape York (Queensland). Wave 1 included 429 people (235 males and 194 females); and wave 2 included 402 people (228 males and 174 females). Current users (used cannabis during the year before interview) described frequency of use, amount consumed, expenditure and dependence symptoms. Other substance use was recorded for 402 people at wave 2. Results: Wave 1: 69% reported lifetime use and 44% current use. Males (55%) were more likely than females (30%) to be current users (P < 0.001). Most (96%) current users described at least weekly use; nearly half (48%) were "heavy" users (≥6 cones/session at least once/week) and 77% met cannabis dependence criteria. Three communities spent up to $AUD14,200/week on cannabis, around $AUD2.0 million/year, or around 9% of community people's total income on cannabis. The majority (79%) of current users wanted to quit or reduce their cannabis use. Wave 2: no difference was observed in the proportion of lifetime (69%, |z| = 0.04, P = 0.968) or current cannabis users (39%, |z| = 1.39, P = 0.164); nor current use among males (71%, |z| = 0.91, P = 0.363) or females (62%, |z| = 0.36, P = 0.719). However, a significant reduction in current users by 15% (|z| = 2.36, P = 0.018) was observed in one community. Of 105 wave 1 current users re-assessed in 2, 29 (27%) had ceased use. These participants reported cost and family commitments as reasons to change and that social support and employment enabled abstinence. Current and lifetime cannabis use were closely associated with all other substance use, particularly tobacco and alcohol (both P > 0.001). Conclusions: High rates of heavy cannabis use in remote Australian Indigenous communities warrant action. Successful cessation among some individuals suggests that significant opportunities are available to support change even where cannabis use may be endemic.

Cannabis consumption and psychosis or schizophrenia development

OBJECTIVE:

Cannabis consumption produces psychopathology, in some cases psychotic episodes, which are of our interest in this work. However, the relationship between cannabis use and psychosis has not been fully elucidated. The objectives of this work are to (1) review the current state of knowledge on the association of cannabis use with the risk of the development of psychosis or psychotic symptoms in people without schizophrenia and (2) assess the consistency of the hypothesis that cannabis use is associated with increased risk of psychosis in people without schizophrenia.

METHOD:

This work included research done in humans until May 2018 with the keywords 'cannabis' and 'psychosis', published in English and Spanish, in the PubMed database.

RESULTS:

In all, 66 papers were analyzed, of which 23 were cohort trials and 43 were reviews.

CONCLUSION:

Cannabis use doubles the risk of developing psychosis in vulnerable people. There even exists a relationship regarding the dose used and the age of first use. Gene-environment interactions that modulate the association between cannabis use and the presence of psychosis have also been described.

Gender as a Moderator of Descriptive Norms and Substance Use among Latino College Students

This study addresses gaps in the literature by testing gender differences in the associations between substance use norms and substance use among Latino college students. Secondary data analysis was conducted using data from the 2009 National College Health Assessment. Participants selected for this study were 4,336 Latino undergraduates. Linear mixed modeling was used to test gender as a moderator of the relationship between alcohol use norms and alcohol use as well as marijuana use norms and marijuana use. Results indicated that the strength of the relationships between norms and substance use was stronger for males than for females. Substance use rates and gender roles differ for Latinos and Latinas and may partially account for the stronger relationship between these constructs for males. Implications for future research and prevention are discussed.

Cortical thickness, cortical surface area and subcortical volumes in schizophrenia and bipolar disorder patients with cannabis use

Cannabis is associated with increased risk for severe mental illness and is commonly used among individuals with schizophrenia or bipolar disorder. In this study we investigated associations between cannabis use and brain structures among patients with schizophrenia or bipolar disorders. Magnetic resonance imaging scans were obtained for 77 schizophrenia and 55 bipolar patients with a history of cannabis use (defined as lifetime use >10 times during one month or abuse/dependence), and 97 schizophrenia, 85 bipolar disorder patients and 277 healthy controls without any previous cannabis use. Cortical thickness, cortical surface area and subcortical volumes were compared between groups. Both hypothesis-driven region-of-interest analyses from 11 preselected brain regions in each hemisphere and exploratory point-by-point analyses were performed. We tested for diagnostic interactions and controlled for potential confounders. After controlling for confounders such as tobacco use and alcohol use disorders we found reduced cortical thickness in the caudal middle frontal gyrus compared to non-user patients and healthy controls. The findings were not significant when patients with co-morbid alcohol and illicit drug use were excluded from the analyses, but onset of cannabis use before illness onset was associated with cortical thinning in the caudal middle frontal gyrus. To conclude, we found no structural brain changes associated with cannabis use among patients with severe mental illness, but the findings indicate excess cortical thinning among those who use cannabis before illness onset. The present findings support the understanding that cannabis use is associated with limited brain effects in schizophrenia as well as bipolar disorder.

Investigation of the COMT Val158Met variant association with age of onset of psychosis, adjusting for cannabis use

OBJECTIVE

COMT rs4680 (Val158Met) genotype moderates the effect of cannabis on the age of onset of psychosis (AoP). We investigated the association between rs4680 and AoP, after adjusting for relevant covariates, in a Canadian Caucasian sample.

METHODS

One hundred and sixty-nine subjects with psychosis were recruited. AoP, defined as age of DSM-IV diagnosis was established using the Structured Clinical Interview for DSM-IV. Cannabis use data were collected using a self-report computerized questionnaire. DNA was extracted from saliva and genotyping of the COMT Val158Met polymorphism was done by SNaPshot and TaqMan assays. Kaplan-Meier analysis results are reported.

RESULTS

In those who had used cannabis before 20 years of age, rs4680 had a trend level effect on AoP (median AoP: Val/Val < Val/Met < Met/Met 19.37, 20.95, 21.24 years, respectively; log-rank test p = .051).

CONCLUSION

Our data are indicative of the need to further investigate the association between the COMT rs4680 variant and AoP in the context of adolescent cannabis use.

Rapid and simple analysis of disease-associated biomarkers of Taiwanese patients with schizophrenia using matrix-assisted laser desorption ionization mass spectrometry

BACKGROUND

Matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS) is an extremely sensitive analytical tool for characterizing biological compounds in bio samples. In this study, we applied MALDI-TOF MS to assess potential protein biomarkers in the peripheral blood mononuclear cells (PBMCs) of patients with schizophrenia in the acute phase, recovery phase and healthy controls in Taiwan.

METHODS

We recruited 40 participants, including 20 pairs of patients diagnosed with schizophrenia in the acute phase, after four-week treatment with drug in the recovery phase, and 20 healthy controls. The schizophrenic patients were diagnosed using Structured Clinical Interview for DSM-IV Axis I Disorders (SCID), and severity was assessed by a positive and negative symptom scale at baseline and at endpoint following four-week treatment with drug. The patients' PBMCs biomarkers were rapidly measured using a technique that combines MALDI-TOF MS and principle component analysis. A receiver operating characteristic curve was created for the evaluated biomarker.

RESULTS

Significant differences in α-defensins 1-3 were found between the patients in acute phase with schizophrenia and the healthy controls, but not between the schizophrenic patients in recovery phase and healthy controls or between the schizophrenic patients in acute phase and in recovery phase.

CONCLUSIONS

α-Defensins can be biomarkers of Taiwanese patients with schizophrenia, thus supporting the hypothesis that the inflammatory response and immunity system is correlated with the pathophysiology of schizophrenia. Moreover, the result also implies that α-defensins may be related in schizophrenia-associated disease not in efficacy of drug-treatment.

Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations

BACKGROUND

Cannabis use is common in North America, especially among young people, and is associated with a risk of various acute and chronic adverse health outcomes. Cannabis control regimes are evolving, for example toward a national legalization policy in Canada, with the aim to improve public health, and thus require evidence-based interventions. As cannabis-related health outcomes may be influenced by behaviors that are modifiable by the user, evidence-based Lower-Risk Cannabis Use Guidelines (LRCUG)-akin to similar guidelines in other health fields-offer a valuable, targeted prevention tool to improve public health outcomes.

OBJECTIVES

To systematically review, update, and quality-grade evidence on behavioral factors determining adverse health outcomes from cannabis that may be modifiable by the user, and translate this evidence into revised LRCUG as a public health intervention tool based on an expert consensus process.

SEARCH METHODS

We used pertinent medical search terms and structured search strategies, to search MEDLINE, EMBASE, PsycINFO, Cochrane Library databases, and reference lists primarily for systematic reviews and meta-analyses, and additional evidence on modifiable risk factors for adverse health outcomes from cannabis use.

SELECTION CRITERIA

We included studies if they focused on potentially modifiable behavior-based factors for risks or harms for health from cannabis use, and excluded studies if cannabis use was assessed for therapeutic purposes.

DATA COLLECTION AND ANALYSIS

We screened the titles and abstracts of all studies identified by the search strategy and assessed the full texts of all potentially eligible studies for inclusion; 2 of the authors independently extracted the data of all studies included in this review. We created Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow-charts for each of the topical searches. Subsequently, we summarized the evidence by behavioral factor topic, quality-graded it by following standard (Grading of Recommendations Assessment, Development, and Evaluation; GRADE) criteria, and translated it into the LRCUG recommendations by the author expert collective on the basis of an iterative consensus process.

MAIN RESULTS

For most recommendations, there was at least "substantial" (i.e., good-quality) evidence. We developed 10 major recommendations for lower-risk use: (1) the most effective way to avoid cannabis use-related health risks is abstinence, (2) avoid early age initiation of cannabis use (i.e., definitively before the age of 16 years), (3) choose low-potency tetrahydrocannabinol (THC) or balanced THC-to-cannabidiol (CBD)-ratio cannabis products, (4) abstain from using synthetic cannabinoids, (5) avoid combusted cannabis inhalation and give preference to nonsmoking use methods, (6) avoid deep or other risky inhalation practices, (7) avoid high-frequency (e.g., daily or near-daily) cannabis use, (8) abstain from cannabis-impaired driving, (9) populations at higher risk for cannabis use-related health problems should avoid use altogether, and (10) avoid combining previously mentioned risk behaviors (e.g., early initiation and high-frequency use).

AUTHORS' CONCLUSIONS

Evidence indicates that a substantial extent of the risk of adverse health outcomes from cannabis use may be reduced by informed behavioral choices among users. The evidence-based LRCUG serve as a population-level education and intervention tool to inform such user choices toward improved public health outcomes. However, the LRCUG ought to be systematically communicated and supported by key regulation measures (e.g., cannabis product labeling, content regulation) to be effective. All of these measures are concretely possible under emerging legalization regimes, and should be actively implemented by regulatory authorities. The population-level impact of the LRCUG toward reducing cannabis use-related health risks should be evaluated. Public health implications. Cannabis control regimes are evolving, including legalization in North America, with uncertain impacts on public health. Evidence-based LRCUG offer a potentially valuable population-level tool to reduce the risk of adverse health outcomes from cannabis use among (especially young) users in legalization contexts, and hence to contribute to improved public health outcomes.

Building smart cannabis policy from the science up

Social attitudes and cultural norms around the issue of substance abuse are shifting rapidly around the world, leading to complex and unpredictable consequences. On the positive side, efforts to more intensely disseminate the scientific evidence for the many connections between chronic substance use and the emergence of measurable and discrete brain dysfunctions, has ushered in an evolving climate of acceptance and a new era of improved access to more effective interventions, at least in the United States. On the negative side, there has been a steady erosion in the public perception of the harms associated with the use of popular drugs, especially cannabis. This worrisome trend has sprouted at the convergence of several forces that have combined, more or less fortuitously, to effectively change long-standing policies away from prohibition and toward decriminalization or legalization. These forces include the outsized popularity of the cannabis plant among recreational users, the unflagging campaign by corporate lobbyists and patient advocates to mainstream its medicinal use, and the honest realization in some quarters of the deleterious impact of the drug war and its draconian cannabis laws, in particular, on society's most vulnerable populations. Updating drug policies is a desirable goal, and significant changes may indeed be warranted. However, there is a real concern when policy changes are hurriedly implemented without the required input from the medical, scientific, or policy research communities. Regardless of how well intentioned, such initiatives are bound to magnify the potential for unintended adverse consequences in the form of far ranging health and social costs. To minimize this risk, science must be front and center in this important policy debate. Here, we review the state of the science on cannabis and cannabinoid health effects, both adverse and therapeutic. We focus on the prevalence of use in different populations, the mechanisms by which cannabis exerts its effects (i.e., via the endocannabinoid system), and the double-edged potential of this system to inspire new medications, on one hand, and to cause short and long term harmful effects on the other. By providing knowledge of cannabis' broad ranging effects, we hope to enable better decision making regarding cannabis legislation and policy implementation.

Irish general practitioner attitudes toward decriminalisation and medical use of cannabis: results from a national survey

Background

Governmental debate in Ireland on the de facto decriminalisation of cannabis and legalisation for medical use is ongoing. A cannabis-based medicinal product (Sativex®) has recently been granted market authorisation in Ireland. This unique study aimed to investigate Irish general practitioner (GP) attitudes toward decriminalisation of cannabis and assess levels of support for use of cannabis for therapeutic purposes (CTP).

Methods

General practitioners in the Irish College of General Practitioner (ICGP) database were invited to complete an online survey. Anonymous data yielded descriptive statistics (frequencies, percentages) to summarise participant demographic information and agreement with attitudinal statements. Chi-square tests and multi-nominal logistic regression were included.

Results

The response rate was 15% (n = 565) which is similar to other Irish national GP attitudinal surveys. Over half of Irish GPs did not support the decriminalisation of cannabis (56.8%). In terms of gender, a significantly higher proportion of males compared with females (40.6 vs. 15%; p < 0.0001) agreed or strongly agreed with this drug policy approach. A higher percentage of GPs with advanced addiction specialist training (level 2) agreed/strongly agreed that cannabis should be decriminalised (54.1 vs. 31.5%; p = 0.021). Over 80% of both genders supported the view that cannabis use has a significant effect on patients’ mental health and increases the risk of schizophrenia (77.3%). Over half of Irish GPs supported the legalisation of cannabis for medical use (58.6%). A higher percentage of those who were level 1-trained (trained in addiction treatment but not to an advanced level) agreed/strongly agreed cannabis should be legalised for medical use (p = 0.003). Over 60% agreed that cannabis can have a role in palliative care, pain management and treatment of multiple sclerosis (MS). In the regression response predicator analysis, females were 66.2% less likely to agree that cannabis should be decriminalised, 42.5% less likely to agree that cannabis should be legalised for medical use and 59.8 and 37.6% less likely to agree that cannabis has a role in palliative care and in the treatment of multiple sclerosis (respectively) than males.

Conclusions

The majority of Irish GPs do not support the present Irish governmental drug policy of decriminalisation of cannabis but do support the legalisation of cannabis for therapeutic purposes. Male GPs and those with higher levels of addiction training are more likely to support a more liberal drug policy approach to cannabis for personal use. A clear majority of GPs expressed significant concerns regarding both the mental and physical health risks of cannabis use. Ongoing research into the health and other effects of drug policy changes on cannabis use is required.

Psychiatric comorbidity associated with synthetic cannabinoid use compared to cannabis

BACKGROUND

Synthetic cannabinoids (SC) use has had a dramatic increase in recent years, but data regarding their adverse effects on mental health is limited. In this study, we compared clinical presentations of SC users with cannabis users in a psychiatric inpatient setting.

METHODS

Digital charts of all patients who were admitted to a dual diagnosis psychiatric unit in one year were reviewed. Patients who had any current substance use disorder were categorized in four groups: (1) SC use and cannabis use (SC+MJ+), (2) SC use without cannabis use (SC+MJ-), (3) cannabis use without SC use (SC-MJ+), and (4) No SC or cannabis use (SC-MJ-).

RESULTS

A total of 594 charts were included. SC+MJ- patients had significantly more psychotic symptoms (OR: 4.44, 95% CI: 1.98-9.94), followed by SC+MJ+ (OR: 3.61, 95% CI: 1.87-6.97) and SC-MJ+ (OR: 1.87, 95%CI: 1.33-2.64) patients. The SC+MJ- group also had more agitation and aggression was most prominent in SC+MJ+ subjects. Multivariate analyses showed that the psychiatric associations of SC and cannabis use remained significant even after controlling for potential confounds such as other substance use.

CONCLUSIONS

The prominent psychiatric features of SC users as compared to cannabis users in an inpatient setting are psychotic presentations and agitation, which have important treatment implications.

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 Effect of Changes in Cannabis Exposure on Psychotic Symptoms in Patients With Comorbid Cannabis Use Disorder

OBJECTIVE

It remains unclear whether there is an association between severity of cannabis use and psychotic symptom severity over time. Shedding light on this under-researched matter could have clinical implications for this patient group.

METHODS

This was a secondary analysis of a randomized, parallel-group, superiority, assessor-blinded trial. We followed 60 patients with dually diagnosed psychosis and cannabis use disorders from the Danish CapOpus trial, which included assessments at baseline, post-treatment (6 months) and 10 months. Cannabis use was registered by self-report assisted by timeline follow-back. Psychotic symptoms were measured using the Positive and Negative Syndrome Scale (PANSS) positive, negative, and general symptoms scores. Analyses were adjusted for potential confounders.

RESULTS

Patients were classified into four categories: minor use (0-30 joints at baseline and 0-9 joints at follow-up; n = 19), moderate use (0-30 joints at baseline and 10-196 joints at follow-up; n = 11), high (reducing) use (31-240 joints at baseline and 0-9 joints at follow-up; n = 9), and severe use (31-240 joints at baseline and 10-196 joints at follow-up; n = 21). Those with severe and persistent cannabis use (severe use group) had significantly higher scores, as compared to those with minor use, on the positive symptom (17.0, 95% CI [4.7-19.2] vs. 12.7, 95% CI [10.4-15.0], respectively, adjusted p < .009) and general symptom (37.4, 95% CI [34.0-40.8] vs. 29.8, 95% CI [26.3-33.3], respectively, adjusted p < .003) scales at follow-up. The severe use group had significantly higher scores, as compared to the moderate use group, on the negative symptom scale at follow-up (17.4, 95% CI [15.1-19.7] vs. 12.5, 95% CI [9.3-15.6], respectively, adjusted p < .02). On the other hand, patients in the high (reducing) use group demonstrated the greatest improvement in psychotic symptoms on all three measures.

CONCLUSIONS

These findings are preliminary and more research must be done to elucidate the relationship between cannabis use and psychosis. Treatment of psychosis and comorbid cannabis use disorder could in the future incorporate treatment strategies emphasising encouragement to reduce cannabis use. CapOpus is registered at clinicaltrials.gov (NCT00484302).

Synthetic Cannabinoids-Further Evidence Supporting the Relationship Between Cannabinoids and Psychosis

Consumption of synthetic mind-altering compounds, also known as "new psychoactive substances," is increasing globally at an alarming rate. Synthetic cannabinoids (SCs) are among the most commonly used new psychoactive substances. They are usually purchased as marijuana-like drugs, marketed as herbal blends and perceived as risk-free by inexperienced users. Yet, contrary to Δ(9)-tetrahydrocannabinol, SCs may lead to severe health consequences, including anxiety, tachycardia, hallucinations, violent behavior, and psychosis. This review focuses on the latest (2010-2015) evidence of psychotic symptoms induced by ingestion of products containing SCs. Reports suggesting that SCs may either exacerbate previously stable psychotic symptoms (in vulnerable individuals) or trigger new-onset psychosis (in individuals with no previous history of psychosis) are reviewed. Pharmacology and toxicology of these compounds are discussed, with particular reference to their psychoactive effects.

Psychosis and Substance Use: Implications for Conditional Release Readiness Evaluations

In Foucha v. Louisiana (1992), the United States Supreme Court ruled that individuals adjudicated not guilty by reason of insanity (NGRI) could not remain in a forensic hospital if they were no longer mentally ill and dangerous. Since this decision, a variety of important questions have arisen related to the insanity defense and what should happen to insanity acquittees post-adjudication. This article provides an analysis of clinical issues confronting forensic examiners when psychosis as a result of substance abuse is the underlying condition supporting an insanity defense. To accomplish this analysis, this article provides the reader with a review of literature showing the complex relationship between psychosis and substance abuse. Second, this article investigates how substance-induced psychosis may impact both insanity opinions and subsequent conditional release decisions. Third, the article aims to provide research-driven information to assist clinicians in conducting conditional release evaluations. Finally, this paper provides a model for evaluating dangerousness in the context of conditional release evaluations. Given the substantial comorbidity between substance abuse and psychosis, it is critical for researchers and clinicians to consider potential effects of substance abuse when evaluating insanity acquittees for conditional release, especially as substance use relates to future dangerousness. Copyright © 2016 John Wiley & Sons, Ltd.

A Qualitative Exploration of U.K. Prisoners’ Experiences of Substance Misuse and Mental Health Difficulties, and the Breaking Free Health and Justice Interventions

This qualitative study explored prisoners’ lived experiences of substance use and mental health difficulties and aimed to examine perceived links between these two areas and how they might be associated with recovery during engagement with the Breaking Free Health and Justice (BFHJ) treatment programs. Interviews were conducted with 32 prisoners receiving treatment for substance use in North-West England. Emerging from prisoners’ interviews were themes relating to difficult life experiences from childhood into adulthood, how these experiences played a role in the emergence of their multiple and complex difficulties, their treatment experiences, and how their current involvement with the criminal justice system acted as a catalyst for positive change, including engagement with the BFHJ programs. This study identified the roles of substance use and mental health difficulties in the lives of participants, identified how their multiple and complex difficulties might be addressed, and provided insights into prisoners’ interpretations of their life experiences.

Cannabis and Psychosis: a Critical Overview of the Relationship

Interest in the relationship between cannabis use and psychosis has increased dramatically in recent years, in part because of concerns related to the growing availability of cannabis and potential risks to health and human functioning. There now exists a plethora of scientific articles addressing this issue, but few provide a clear verdict about the causal nature of the cannabis-psychosis association. Here, we review recent research reports on cannabis and psychosis, giving particular attention to how each report provides evidence relating to two hypotheses: (1) cannabis as a contributing cause and (2) shared vulnerability. Two primary kinds of data are brought to bear on this issue: studies done with schizophrenic patients and studies of first-episode psychosis. Evidence reviewed here suggests that cannabis does not in itself cause a psychosis disorder. Rather, the evidence leads us to conclude that both early use and heavy use of cannabis are more likely in individuals with a vulnerability to psychosis. The role of early and heavy cannabis use as a prodromal sign merits further examination, along with a variety of other problem behaviors (e.g., early or heavy use of cigarettes or alcohol and poor school performance). Future research studies that focus exclusively on the cannabis-psychosis association will therefore be of little value in our quest to better understand psychosis and how and why it occurs.

Does a reduction in alcohol use by Dutch high school students relate to higher use of tobacco and cannabis?

Background

Substance use of adolescents was investigated in a region around Amsterdam, the Netherlands, in the period 2005–2009. The study was intended to find out to what extent behaviour related to different substances are interrelated and how trends develop in different subgroups.

Methods

Two cross-sectional surveys were conducted among Dutch students in the second and fourth year of secondary school, aged 13-16 [n = 1,854 in 2005; n = 2,088 in 2009] by making use of an online questionnaire including questions about alcohol consumption, tobacco use (smoking behaviour) and cannabis use. Two educational levels were included.

Results

Decreases in alcohol consumption, tobacco and cannabis use were found between 2005 and 2009. The strongest decline was seen in alcohol consumption. Last month drinking decreased from 61.8 % in 2005 to 36.5 % in 2009. Last month binge drinking decreased from 38.7 % in 2005 to 24.0 % in 2009. Reduced alcohol consumption was found among boys and girls, for all ages and in both educational levels. Changes were strongest among 13-year-olds. Weekly or daily smoking declined between 2005 and 2009 among 13-year-olds, girls and students in the lower schooling level. Last month cannabis use decreased among girls and students in the higher schooling level. In both 2005 and 2009 clustering with alcohol consumption was found for the use of other substances.

Conclusions

Between 2005 and 2009 alcohol consumption strongly decreased among high school students. This may be due to the national prevention campaign which in the same period highlighted the importance of not drinking before the age of 16. The decrease in smoking and cannabis use between 2005 and 2009 may be due to clustering with alcohol consumption. A reduction in the use of alcohol in adolescence did not lead to replacement by tobacco or cannabis use.

Illicit drug use, early age at first use and risk of premenstrual syndrome: A longitudinal study

BACKGROUND

Premenstrual syndrome (PMS) is common among women of reproductive age. Limited studies have investigated the long-term association between illicit drug use and PMS.

METHODS

The 1973-1978 cohort from the Australian Longitudinal Study on Women's Health, a prospective cohort study, was followed up for 13-year from 2000 to 2012. Data were collected through self-reported questionnaires on all variables, including PMS, illicit drug use and a range of sociodemographic, lifestyle, reproductive and psychological factors.

RESULTS

When the women were 22-27 years of age, over 40% use illicit drug in the last 12 months, 9% first used drug before age 15 years and approximately 35% reported PMS. Over the study period, the prevalence of drug use in the last 12 months declined whereas that of PMS remained fairly stable except an increase when they were 34-39 years old. Generalised estimating equations analysis showed that, compared to never drug users, significantly higher odds of reporting PMS were detected for illicit drug use in the last 12 months: multiple drugs (odds ratio (OR) 1.31, 95% confidence interval (CI) 1.21, 1.43), exclusive marijuana (OR 1.23, 95% CI 1.08, 1.40). A higher odds of PMS was identified for age at first drug use before 15 years (OR 1.20, 95% CI 1.03, 1.40).

CONCLUSIONS

Illicit drug use in the last 12 months, especially early age at first use and multiple drug use, is associated with increased risk of PMS. However current study is unable to prove causality.

Comorbid substance use disorders in schizophrenia: a latent class approach

Schizophrenia is a complex psychiatric disorder with a characteristic disease course and heterogeneous etiology. While substance use disorders and a family history of psychosis have individually been identified as risk factors for schizophrenia, it is less well understood if and how these factors are related. To address this deficiency, we examined the relationship between substance use disorders and family history of psychosis in a sample of 1219 unrelated patients with schizophrenia. The lifetime rate of substance use disorders in this sample was 50%, and 30% had a family history of psychosis. Latent class mixture modeling identified three distinct patient subgroups: (1) individuals with low probability of substance use disorders; (2) patients with drug and alcohol abuse, but no symptoms of dependence; and (3) patients with substance dependence. Substance use was related to being male, to a more severe disease course, and more acute symptoms at assessment, but not to an earlier age of onset of schizophrenia or a specific pattern of positive and negative symptoms. Furthermore, substance use in schizophrenia was not related to a family history of psychosis. The results suggest that substance use in schizophrenia is an independent risk factor for disease severity and onset.

The association between cannabis abuse and subsequent schizophrenia: a Swedish national co-relative control study

BACKGROUND

Although cannabis abuse (CA) is known to be associated with schizophrenia, the causal nature of this association is unclear, with prodromal effects complicating its interpretation.

METHOD

From Swedish national registry databases, we used a co-relative case-control design with full-sibling, half-sibling and first-cousin comparisons, alongside a general Swedish population sample. Using ICD codes, 5456 individuals with an initial diagnosis of schizophrenia (2000-2010) were matched with five schizophrenia-free controls. We further identified first-cousin, half-sibling and full-sibling pairs discordant for CA and statistically extrapolated results for discordant monozygotic (MZ) twins.

RESULTS

Within the general Swedish population, CA was strongly associated with later schizophrenia [odds ratio (OR) 10.44, 95% confidence interval (CI) 8.99-12.11]. This association was substantially attenuated both by increasing temporal delays between CA exposure and schizophrenia diagnosis and by controlling for increasing degrees of familial confounding. Extrapolated discordant MZ pairs suggested that fully controlling for confounding familial factors reduced the association between CA and later schizophrenia to more modest levels (ORs of approximately 3.3 and 1.6 with 3- and 7-year temporal delays respectively). Opiate, sedative, cocaine/stimulant and hallucinogen abuse were also strongly associated with subsequent schizophrenia in the general population. After controlling for familial confounding, only cocaine/stimulant exposure remained associated.

CONCLUSIONS

CA has an appreciable causal impact on future risk for schizophrenia. However, population-based estimates of cannabis-schizophrenia co-morbidity substantially overestimate their causal association. Predictions of the cases of schizophrenia that might be prevented by reduced cannabis consumption based on population associations are therefore likely to be considerably overestimated.

Cannabis and adolescent brain development

Heavy cannabis use has been frequently associated with increased rates of mental illness and cognitive impairment, particularly amongst adolescent users. However, the neurobiological processes that underlie these associations are still not well understood. In this review, we discuss the findings of studies examining the acute and chronic effects of cannabis use on the brain, with a particular focus on the impact of commencing use during adolescence. Accumulating evidence from both animal and human studies suggests that regular heavy use during this period is associated with more severe and persistent negative outcomes than use during adulthood, suggesting that the adolescent brain may be particularly vulnerable to the effects of cannabis exposure. As the endocannabinoid system plays an important role in brain development, it is plausible that prolonged use during adolescence results in a disruption in the normative neuromaturational processes that occur during this period. We identify synaptic pruning and white matter development as two processes that may be adversely impacted by cannabis exposure during adolescence. Potentially, alterations in these processes may underlie the cognitive and emotional deficits that have been associated with regular use commencing during adolescence.

Synthetic cannabinoid use among patients in residential substance use disorder treatment: prevalence, motives, and correlates

BACKGROUND

The abuse of synthetic cannabinoids has emerged as a public health concern over the past few years, yet little data exist characterizing the use of synthetic cannabinoids, particularly among patients seeking substance use disorder (SUD) treatment. In a sample of patients entering residential SUD treatment, we examined the prevalence of and motivations for synthetic cannabinoid use, and examined relationships of synthetic cannabinoid use with other substance use and demographic characteristics.

METHODS

Patients (N=396; 67% male, 75% White, Mage=34.8) completed self-report screening surveys about lifetime prevalence of synthetic cannabinoid use, route of administration, and motives for use.

RESULTS

A total of 150 patients (38%) reported using synthetic cannabinoids in their lifetimes, primarily by smoking (91%). Participants chose multiple motives for use and the most commonly endorsed included curiosity (91%), feeling good/getting high (89%), relaxation (71%), and getting high without having a positive drug test (71%). Demographically, those who used synthetic cannabinoids were younger and more were White. They had higher rates of other substance use and higher scores on measures of depression and psychiatric distress.

CONCLUSIONS

Lifetime synthetic cannabinoid use was relatively common in SUD patients and many of those who used it reported doing so because they believed it would not result in a positive drug test. Further research is needed to characterize the extent of synthetic cannabinoid use among SUD treatment samples, and to establish understanding of the longitudinal trajectories of synthetic cannabinoid use in combination with other substance use, psychiatric distress, and treatment outcomes.

One year follow-up of alcohol and illicit substance use in first-episode psychosis: does gender matter?

Longitudinal studies on first-episode psychosis (FEP) patients have shown a decrease of substance use disorders (SUDs) over the first years of illness, but there has been less focus on the gender aspect. The present study examines stability of alcohol and illicit substance use, with specific focus on gender, in a one year follow-up investigation of 154 FEP patients (91 men, 63 women) in Oslo, Norway, using criteria for DSM-IV substance use disorder diagnosis, the Alcohol Use Disorders Identification Test (AUDIT) and the Drug Use Disorders Identification Test (DUDIT). The results show that cannabis was the most frequently used illicit substance at both times. Significantly more men (34%) than women (13%) had a current illicit SUD at baseline. At follow-up, the rate of illicit SUDs was significantly reduced in men (18%) but not in women (11%). There were no significant gender differences in the rate of current alcohol use disorders (AUD) (men 14%; women 8%) at baseline, and no significant reduction in AUD in any of the genders at follow-up. At follow-up, total AUDIT and DUDIT scores were reduced in men only. In conclusion, the high and persistent rate of SUDs, particularly of cannabis, among men and women during the first year of treatment for psychosis should be addressed in the clinical management of the patients. Female FEP patients who are also substance users may be particularly vulnerable in this regard and warrant closer attention.

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.

A preliminary study of functional brain activation among marijuana users during performance of a virtual water maze task

Numerous studies have reported neurocognitive impairments associated with chronic marijuana use. Given that the hippocampus contains a high density of cannabinoid receptors, hippocampal-mediated cognitive functions, including visuospatial memory, may have increased vulnerability to chronic marijuana use. Thus, the current study examined brain activation during the performance of a virtual analogue of the classic Morris water maze task in 10 chronic marijuana (MJ) users compared to 18 nonusing (NU) comparison subjects. Imaging data were acquired using blood oxygen level-dependent (BOLD) functional MRI at 3.0 Tesla during retrieval (hidden platform) and motor control (visible platform) conditions. While task performance on learning trials was similar between groups, MJ users demonstrated a deficit in memory retrieval. For BOLD fMRI data, NU subjects exhibited greater activation in the right parahippocampal gyrus and cingulate gyrus compared to the MJ group for the Retrieval-Motor Control contrast (NU > MJ). These findings suggest that hypoactivation in MJ users may be due to differences in the efficient utilization of neuronal resources during the retrieval of memory. Given the paucity of data on visuospatial memory function in MJ users, these findings may help elucidate the neurobiological effects of marijuana on brain activation during memory retrieval.

Does olanzapine inhibit the psychomimetic effects of Δ⁹-tetrahydrocannabinol?

Δ⁹-Tetrahydrocannabinol (THC) produces transient psychomimetic effects in healthy volunteers, constituting a pharmacological model for psychosis. The dopaminergic antagonist haloperidol has previously been shown to reduce these effects. This placebo-controlled, cross-over study in 49 healthy, male, mild cannabis users aimed to further explore this model by examining the effect of a single oral dose of olanzapine (with dopaminergic, serotonergic, adrenergic, muscarinergic and histaminergic properties) or two oral doses of diphenhydramine (histamine antagonist) on the effects of intrapulmonarily administered THC. Transient psychomimetic symptoms were seen after THC administration, as measured on the positive and negative syndrome scale (20.6% increase on positive subscale, p<0.001) and the visual analogue scale for psychedelic effects (increase of 10.7 mm on feeling high). Following the combination of THC and olanzapine, the positive subscale increased by only 13.7% and feeling high by only 8.7 mm. This reduction of THC effects on the positive subscale failed to reach statistical significance (p=0.066). However, one-third of the subjects did not show an increase in psychomimetic symptoms after THC alone. Within responders, olanzapine reduced the effects of THC on the positive subscale (p=0.005). Other outcome measures included pharmacokinetics, eye movements, postural stability, pupil/iris ratio, and serum concentrations of cortisol and prolactin.

Popular intoxicants: what lessons can be learned from the last 40 years of alcohol and cannabis regulation?

In this paper we discuss the relative physical, psychological and social harms of the two most frequently used intoxicant drugs in the UK, namely cannabis and alcohol. Over the past 40 years, the use of both drugs has risen significantly with differential consequences. It is argued that increased policing of cannabis use under the current drug classification system will lead to increased criminalization of young people, but is unlikely to significantly reduce the rates of schizophrenia and psychosis. In comparison, increases in alcohol drinking are related to significant increases in liver cirrhosis hospital admissions and mortality, at a time when mortality rates from other major causes are on the decline. A recent expert-led comparison of the health and social harms to the user and to others caused by the most commonly used drugs in the UK showed alcohol to be more than twice as harmful as cannabis to users, and five times as harmful as cannabis to others. The findings underline the need for a coherent, evidence-based drugs policy that enables individuals to make informed decisions about the consequences of their drug use.

Lower Risk Cannabis use Guidelines for Canada (LRCUG): a narrative review of evidence and recommendations

OBJECTIVES

More than one in ten adults--and about one in three young adults--report past year cannabis use in Canada. While cannabis use is associated with a variety of health risks, current policy prohibits all use, rather than adopting a public health approach focusing on interventions to address specific risks and harms as do policies for alcohol. The objective of this paper was to develop 'Lower Risk Cannabis Use Guidelines' (LRCUG) based on research evidence on the adverse health effects of cannabis and factors that appear to modify the risk of these harms.

METHODS

Relevant English-language peer-reviewed publications on health harms of cannabis use were reviewed and LRCUG were drafted by the authors on the basis of a consensus process.

SYNTHESIS

The review suggested that health harms related to cannabis use increase with intensity of use although the risk curve is not well characterized. These harms are associated with a number of potentially modifiable factors related to: frequency of use; early onset of use; driving after using cannabis; methods and practices of use and substance potency; and characteristics of specific populations. LRCUG recommending ways to reduce risks related to cannabis use on an individual and population level--analogous to 'Low Risk Drinking Guidelines' for alcohol--are presented.

CONCLUSIONS

Given the prevalence and age distribution of cannabis use in Canada, a public health approach to cannabis use is overdue. LRCUG constitute a potentially valuable tool in facilitating a reduction of health harms from cannabis use on a population level.

A systematic meta-review grading the evidence for non-genetic risk factors and putative antecedents of schizophrenia

INTRODUCTION

Identifying the relative strength of evidence associated with non-genetic risk factors and putative antecedents of schizophrenia will guide research and may inform the design of early detection and intervention strategies.

AIMS

To present and quality assess current evidence for non-genetic risk factors and putative antecedents derived from well-conducted systematic reviews that report pooled data.

METHOD

Medline, Embase, CINAHL, Current Contents, and PsycINFO databases were searched systematically, and supplemented by hand searching. Review reporting quality was assessed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, review methodology was assessed using the Assessment of Multiple Systematic Reviews (AMSTAR) checklist, and evidence quality was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Twenty-four reviews met inclusion criteria. The risk factors with the highest quality evidence, reporting medium effect sizes, were advanced paternal age, obstetric complications, and cannabis use. The strongest evidence among the putative antecedents was identified for motor dysfunction and low IQ.

CONCLUSIONS

More research is required that applies sound methodological practices, taking into consideration specificity for schizophrenia and possible confounding factors, to robustly identify the non-genetic risk factors and putative antecedents of schizophrenia.

Cannabisbezogene Störungen bei Jugendlichen und jungen Erwachsenen

Umfang des Problems: Die Zahlen für Lebenszeitprävalenzen von Cannabis sowie regelmäßige Konsummuster unter Jugendlichen zeigen nach starkem Anstieg der Vorjahre in den Jahren 2007 und 2008 erstmals einen leichten Rückgang. Die Behandlungsnachfrage scheint dagegen weiter anzusteigen, die Prävalenzen cannabisbezogener Störungen bei Jugendlichen und jungen Erwachsenen sind bereits sehr hoch. Ätiologie: Individuelle Vulnerabilität und Risikofaktoren prägen in einer Interaktion von psychosozialen, substanzbezogenen, intra- und interpersonellen (familiären) Variablen die Initiation sowie die Progression zu regelmäßigem Konsum, zum Teil resultieren cannabisbezogene Störungen. Behandlung: Die Behandlung dieser Klientel erfordert ein hohes Maß an störungs- und altersspezifischer Orientierung. Besondere psychosoziale und suchtmedizinische Umstände sowie die Auswirkungen des Cannabiskonsums müssen ebenso berücksichtigt werden wie die entwicklungspsychologischen und –psychopathologischen Besonderheiten des Kindes-, Jugend- und jungen Erwachsenenalters. Aufgrund oft gering ausgeprägter Eigenmotivation zu Verhaltensänderung und Behandlung kommt motivationsfördernden Ansätzen eine wichtige Bedeutung zu.

Health effects of using cannabis for therapeutic purposes: a gender analysis of users' perspectives

The purpose of this qualitative study was to describe how individuals who self-report therapeutic use of cannabis perceive its health effects. Data from 23 individual interviews were transcribed and analyzed. Understandings of gendered roles and identities were used to explore the data and interpret differences in perceptions. Descriptions of the health benefits of cannabis for therapeutic purposes included cannabis as life preserving, a disease therapy, a medicine for the mind, a means for self-management, and a way to manage addiction. Self-management of risks focused on the potential effects of excessive use, smoking-related risks, and purchasing precautions. Although the reports of women and men were similar in many respects, there were important differences in patterns and practices of use that reflected gender influences. Insights from the study provide direction for developing gender-specific information to support decision making and usage for therapeutic users.