The effects of the Cannabis Expiation Notice System on the prevalence of cannabis use in South Australia: evidence from the National Drug Strategy Household Surveys 1985-95

This study sought to examine the impact of the Cannabis Expiation Notice (CEN) scheme on the prevalence of lifetime and weekly cannabis use in South Australia. Data from five National Drug Strategy Household Surveys between 1985 and 1995 were examined to test for differences in trends in self-reported: (1) lifetime cannabis use; and (2) current weekly cannabis use, after controlling for age and gender, between South Australia and the other states and territories. Between 1985 and 1995, rates of lifetime cannabis use increased in SA from 26% to 36%. There were also significant increases in Victoria (from 26% to 32%), Tasmania (from 21% to 33%) and New South Wales (from 26% to 33%). The increase in South Australia was significantly greater than the average increase throughout the rest of Australia, but the other Australian states differed in their rates of change. Victoria and Tasmania had similar rates of increase to South Australia; New South Wales, Queensland and Western Australia showed lower rates of increase; and the Northern Territory and the Australian Capital Territory had high rates that did not change during the period. There was no statistically significant difference between SA and the rest of Australia in the rate of increase in weekly cannabis use. While there was a greater increase in self- reported lifetime cannabis use in South Australia between 1985 and 1995 than in the average of the other Australian jurisdictions it is unlikely that this increase is due to the CEN system, because similar increases occurred in Tasmania and Victoria (where there was no change in the legal status of cannabis use), and there was no increase in the rate of weekly cannabis use in South Australia over the same period.

The effects of adolescent cannabis use on educational attainment: a review

This paper reviews research examining the link between cannabis use and educational attainment among youth. Cross-sectional studies have revealed significant associations between cannabis use and a range of measures of educational performance including lower grade point average, less satisfaction with school, negative attitudes to school, increased rates of school absenteeism and poor school performance. However, results of cross-sectional studies cannot be used to determine whether cannabis use causes poor educational performance, poor educational performance is a cause of cannabis use or whether both outcomes are a reflection of common risk factors. Nonetheless, a number of prospective longitudinal studies have indicated that early cannabis use may significantly increase risks of subsequent poor school performance and, in particular, early school leaving. This association has remained after control for a wide range of prospectively assessed covariates. Possible mechanisms underlying an association between early cannabis use and educational attainment include the possibility that cannabis use induces an 'amotivational syndrome' or that cannabis use causes cognitive impairment. However, there appears to be relatively little empirical support for these hypotheses. It is proposed that the link between early cannabis use and educational attainment arises because of the social context within which cannabis is used. In particular, early cannabis use appears to be associated with the adoption of an anti-conventional lifestyle characterized by affiliations with delinquent and substance using peers, and the precocious adoption of adult roles including early school leaving, leaving the parental home and early parenthood.

Reducing the harms caused by cannabis use: the policy debate in Australia

The debate about cannabis policy in Australia has revolved around the harms that cannabis causes to users and the community, on the one hand, and the harms that are caused by the prohibition of its use, on the other. This paper assesses evidence on: (1) the harms caused to users and the community by cannabis use (derived from the international scientific literature) and (2) the harms that arise from prohibition (as reflected in Australian research). The most probable harms caused by cannabis use include: an increased risk of motor vehicle accidents; respiratory disease; dependence; adverse effects on adolescent development; and the exacerbation of psychosis. The harms of the current prohibition on cannabis use policy are less tangible but probably include: the creation of a large blackmarket; disrespect for a widely broken law; harms to the reputation of the unlucky few cannabis users who are caught and prosecuted; lack of access to cannabis for medical uses; and an inefficient use of law enforcement resources. Cannabis policy unavoidably involves trade offs between competing values that should be made by the political process. Australian cannabis policy has converged on a solution which continues to prohibit cannabis but reduces the severity of penalties for cannabis use by either removing criminal penalties or diverting first time cannabis offenders into treatment and education. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.

Characteristics of DSM-IV and ICD-10 cannabis dependence among Australian adults: results from the National Survey of Mental Health and Wellbeing

A representative sample (n = 10 641) of Australian adults completed a structured diagnostic interview assessing the prevalence of mental and substance use disorders in the last year. The prevalence of DSM-IV (1.5%) and ICD-10 (1.7%) cannabis dependence was similar. DSM-IV and ICD-10 dependence criteria comprised unidimensional syndromes. The most common symptoms among dependent and non-dependent users were difficulties with controlling use and withdrawal, although there were marked differences in symptom prevalence. Dependent users reported a median of four symptoms. There was good to excellent diagnostic concordance (kappas = 0.7-0.9) between systems for dependence but not for abuse/harmful use (Y = 0.4). These findings provide some support for the validity of cannabis dependence. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.

Allowing the medical use of cannabis

Cannabis has been advocated as a treatment for nausea, vomiting, wasting, pain and muscle spasm in cancer, HIV/AIDS, and neurological disorders. Such uses are prohibited by law; cannabinoid drugs are not registered for medical use in Australia and a smoked plant product is unlikely to be registered. A New South Wales Working Party has recommended granting exemption from prosecution to patients who are medically certified to have specified medical conditions. This proposal deserves to be considered by other State and Territory governments.

The relationship between cannabis use and other substance use in the general population

This study examined if (1) there is an association in the general population between cannabis use, DSM-IV abuse and dependence, and other substance use and DSM-IV substance abuse/dependence; (2) if so, is it explained by demographic characteristics or levels of neuroticism? It used data from the Australian National Survey of Mental Health and Well-Being (NSMHWB), a stratified, multistage probability sample of 10641 adults, representative of the general population. DSM-IV diagnoses of substance abuse and dependence were derived using the Composite International Diagnostic Interview (CIDI). There was a strong bivariate association between involvement with cannabis use in the past 12 months and other substance use, abuse and dependence. In particular, cannabis abuse and dependence were highly associated with increased risks of other substance dependence. These associations remained after including other variables in multiple regression. Cannabis use without disorder was strongly related to other drug use, an association that was not explained by other variables considered here. The high likelihood of other substance use and substance use disorders needs to be considered among persons seeking treatment for cannabis use problems. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.

Co-morbidity between alcohol, tobacco and cannabis use: reply to David Fergusson

No abstract

Cannabis use and cancer (Editorial)

No Abstract

Testing hypotheses about the relationship between cannabis use and psychosis

Aim: To model the impact of rising rates of cannabis use on the incidence and prevalence of psychosis under four hypotheses about the relationship between cannabis use and psychosis. Methods: The study modelled the effects on the prevalence of schizophrenia over the lifespan of cannabis in eight birth cohorts: 1940-1944, 1945-1949, 1950-1954, 1955-1959, 1960-1964, 1965-1969, 1970-1974, 1975-1979. It derived predictions as to the number of cases of schizophrenia that would be observed in these birth cohorts, given the following four hypotheses: (1) that there is a causal relationship between cannabis use and schizophrenia; (2) that cannabis use precipitates schizophrenia in vulnerable persons; (3) that cannabis use exacerbates schizophrenia; and (4) that persons with schizophrenia are more liable to become regular cannabis users. Results: There was a steep rise in the prevalence of cannabis use in Australia over the past 30 years and a corresponding decrease in the age of initiation of cannabis use. There was no evidence of a significant increase in the incidence of schizophrenia over the past 30 years. Data on trends the age of onset of schizophrenia did not show a clear pattern. Cannabis use among persons with schizophrenia has consistently been found to be more common than in the general population. Conclusions: Cannabis use does not appear to be causally related to the incidence of schizophrenia, but its use may precipitate disorders in persons who are vulnerable to developing psychosis and worsen the course of the disorder among those who have already developed it. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.