Cannabis psychosis: examining the evidence for a distinctive psychopathology in a systematic and narrative review.

BACKGROUND: The term "cannabis psychosis" has become ubiquitous in the psychiatric literature. Few authors have described the precise psychopathology of this potentially distinct subtype of psychosis. Specifically, little attention has been paid to exploring whether cannabis psychosis is characterized by a psychopathology which is different from that of other types of psychosis. OBJECTIVE: The purpose of this paper was to systematically review the literature for evidence of a specific constellation of symptoms which are consistently characteristic of cannabis psychosis within an inpatient psychiatric setting and to determine whether these combine to create a psychopathology which is distinct from that of other types of psychosis. METHOD: Systematic review using Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. RESULTS: 13 studies of the 439 identified met the inclusion criteria. Only eight studies had sufficient internal and external validity to allow comparison in a narrative format of the psychopathology present, compared with controls. Of these eight selected studies, seven reported at least one significant difference (p < .05) in the psychopathology of the cannabis group to the control group used as a comparator. DISCUSSION AND CONCLUSION: This study should be interpreted with great caution and conclusions should not be generalized. These findings do not suggest that "cannabis psychosis" does not exist, only that from a psychopathological perspective it may not be qualitatively any different from other forms of psychosis. Future research in this area needs to focus on clarifying the definition or description of "cannabis psychosis" and the use of standardized robust experimental and/or observational designs to eliminate heterogeneity that may lead to inconclusive results.

The epidemiology of addiction in Sub-Saharan Africa: a synthesis of reports, reviews, and original articles.

Use of alcohol and other psychoactive substances is associated with serious social and public health problems, but the extent of the problem in Sub-Saharan Africa is not well known. We set out to review epidemiological publications on alcohol and other psychoactive substances in Sub-Saharan Africa by performing a systematic search of electronic databases and paper records. Ten Sub-Saharan African countries are among the 22 in the world with the highest increase in per capita alcohol consumption. Cannabis, tobacco, and khat are widely used, and use of cocaine, stimulants, and heroin is increasing. More epidemiological research and implementation and evaluation of interventions is needed. Collaboration between African researchers and those in developed countries could help.

Substance misuse and psychiatric comorbidity in adolescents.

PURPOSE OF REVIEW: Many young people are misusing and becoming dependent on multiple substances (especially nicotine, alcohol, and cannabis), with a complex variety of psychological effects. RECENT FINDINGS: Analysis of interactions between smoking, drinking, and cannabis use indicates that the relationship between substance use and psychiatric comorbidity is primarily explained by regular smoking. In some studies the use of cannabis on a regular basis was associated with an increased risk of psychiatric illness. This is by no means the case for all studies, so this area of work remains controversial. Children with attention deficit hyperactivity disorder who are substance misusers have a poorer prognosis than those without it so there is concern about treatment with stimulant drugs: this fear appears not to be substantiated by one study. Young people with anxiety disorders are at increased risk of substance use disorders. Clinical trials for adolescent substance abuse treatment have provided support for the benefits of cognitive behavioural interventions. There is an accumulating evidence base for pharmacological treatment for adult substance misusers that can inform treatment for younger patients. It is estimated that, of those adolescents who were likely to be in need of help, only about 9% received treatment. SUMMARY: Since psychiatric disorders beginning in childhood may continue into adult life, there is an opportunity to intervene to prevent or reduce conditions complicated by substance misuse, if services are accessible. The need for longitudinal work is vital to explore the patterns of comorbidity, and implement and evaluate appropriate treatment interventions.

Prevalence of comorbid psychiatric illness and substance misuse in primary care in England and Wales.

STUDY OBJECTIVE: To estimate the annual period prevalence of co-occurring psychiatric illness and substance misuse among patients in primary care. DESIGN: Analysis of the general practice research database. SETTING: England and Wales, 1993-1998. PARTICIPANTS: Registered patients at 230 general practices representing 3.1% of the population. A comorbid case was defined as one with both a psychiatric diagnosis and substance misuse diagnosis (not including alcohol or tobacco) within a calendar year. A potentially chronic comorbid case was one that met this definition and, in addition, was treated in subsequent years for either a psychiatric condition or substance misuse. MAIN RESULTS: The annual period prevalence of comorbidity increased from 50/100 000 patient years of exposure (PYE) to 80/100 000 PYE, an increase of 62% during the study period. Rates of comorbid psychoses, comorbid schizophrenia, and comorbid paranoia increased by 147%, 128%, and 144%. The average age of comorbid cases decreased from 38 years to 34 years. Over 80% of comorbid cases were newly diagnosed in each study year, although many are treated in subsequent years for either psychiatric illness or substance misuse. CONCLUSIONS: This study provides data on the nature and extent of comorbidity in primary care in England and Wales. As the comorbidity rate is increasing by about 10% each year, and as comorbid cases are becoming younger, it is probable that the comorbidity rate will have increased beyond the study end point.

Psychological and social sequelae of cannabis and other illicit drug use by young people: a systematic review of longitudinal, general population studies.

BACKGROUND: Use of illicit drugs, particularly cannabis, by young people is widespread and is associated with several types of psychological and social harm. These relations might not be causal. Causal relations would suggest that recreational drug use is a substantial public health problem. Non-causal relations would suggest that harm-reduction policy based on prevention of drug use is unlikely to produce improvements in public health. Cross-sectional evidence cannot clarify questions of causality; longitudinal or interventional evidence is needed. Past reviews have generally been non-systematic, have often included cross-sectional data, and have underappreciated the extent of methodological problems associated with interpretation. METHODS: We did a systematic review of general population longitudinal studies reporting associations between illicit drug use by young people and psychosocial harm. FINDINGS: We identified 48 relevant studies, of which 16 were of higher quality and provided the most robust evidence. Fairly consistent associations were noted between cannabis use and both lower educational attainment and increased reported use of other illicit drugs. Less consistent associations were noted between cannabis use and both psychological health problems and problematic behaviour. All these associations seemed to be explicable in terms of non-causal mechanisms. INTERPRETATION: Available evidence does not strongly support an important causal relation between cannabis use by young people and psychosocial harm, but cannot exclude the possibility that such a relation exists. The lack of evidence of robust causal relations prevents the attribution of public health detriments to illicit drug use. In view of the extent of illicit drug use, better evidence is needed.