Edmund Silins

Cannabis use and educational achievement: Findings from three Australasian cohort studies

BACKGROUND The associations between age of onset of cannabis use and educational achievement were examined using data from three Australasian cohort studies involving over 6000 participants. The research aims were to compare findings across studies and obtain pooled estimates of association using meta-analytic methods. METHODS Data on age of onset of cannabis use (<15, 15-17, never before age 18) and three educational outcomes (high school completion, university enrolment, degree attainment) were common to all studies. Each study also assessed a broad range of confounding factors. RESULTS There were significant (p<.001) associations between age of onset of cannabis use and all outcomes such that rates of attainment were highest for those who had not used cannabis by age 18 and lowest for those who first used cannabis before age 15. These findings were evident for each study and for the pooled data, and persisted after control for confounding. There was no consistent trend for cannabis use to have greater effect on the academic achievement of males but there was a significant gender by age of onset interaction for university enrolment. This interaction suggested that cannabis use by males had a greater detrimental effect on university participation than for females. Pooled estimates suggested that early use of cannabis may contribute up to 17% of the rate of failure to obtain the educational milestones of high school completion, university enrolment and degree attainment. CONCLUSIONS Findings suggest the presence of a robust association between age of onset of cannabis use and subsequent educational achievement.

Cannabis and depression: An integrative data analysis of four Australasian cohorts☆

BACKGROUND This study presents an integrative data analysis of the association between frequency of cannabis use and severity of depressive symptoms using data from four Australasian cohort studies. The integrated data comprised observations on over 6900 individuals studied on up to seven occasions between adolescence and mature adulthood. METHODS Repeated measures data on frequency of cannabis use (not used/<monthly/≥monthly/≥weekly) and concurrently assessed depression scores were pooled over the four cohorts. Regression models were fitted to estimate the strength of association between cannabis use and depression. Fixed effects regression methods were used to control for confounding by non-observed fixed factors. RESULTS Increasing frequency of cannabis use was associated with increasing depressive symptoms (p<0.001). In the pooled data weekly users of cannabis had depression scores that were 0.32 (95%CI 0.27-0.37) SD higher than non-users. The association was reduced but remained significant (p<0.001) upon adjustment for confounding. After adjustment depression scores for weekly users were 0.24 (95%CI 0.18-0.30) SD higher than non-users. The adjusted associations were similar across cohorts. There was a weak age×cannabis use interaction (p<0.05) suggesting that the association was strongest in adolescence. Attempts to further test the direction of causality using SEM methods proved equivocal. CONCLUSIONS More frequent cannabis use was associated with modest increases in rates of depressive symptoms. This association was stronger in adolescence and declined thereafter. However, it was not possible from the available data to draw a definitive conclusion as to the likely direction of causality between cannabis use and depression.

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

Over the past five years, the release of cohort studies assessing the link between cannabis and psychosis has increased attention on this relationship. Existing reviews generally conclude that these cohort studies show cannabis has a causal relationship to psychosis, or at least that one cannot be excluded. Few studies have evaluated the relative strengths and limitations of these methodologically heterogeneous cohort studies, and how their relative merits and weaknesses might influence the way the link between cannabis use and psychosis is interpreted. This paper reviews the methodological strengths and limitations of major cohort studies which have looked at the link between cannabis and psychosis, and considers research findings against criteria for causal inference. Cohort studies that assessed the link between cannabis and psychosis were identified through literature searches using relevant search terms and MEDline, PsycINFO and EMBASE. Reference lists of reviews and key studies were hand searched. Only prospective studies of general population cohorts were included. Findings were synthesised narratively. A total of 10 key studies from seven general population cohorts were identified by the search. Limitations were evident in the measurement of psychosis, consideration of the short-term effects of cannabis intoxication, control of potential confounders and the measurement of drug use during the follow-up period. Pre-existing vulnerability to psychosis emerged as an important factor that influences the link between cannabis use and psychosis. Whilst the criteria for causal association between cannabis and psychosis are supported by the studies reviewed, the contentious issue of whether cannabis use can cause serious psychotic disorders that would not otherwise have occurred cannot be answered from the existing data. Further methodologically robust cohort research is proposed and the implications of how evidence informs policy in the case of uncertainty is discussed.

Qualitative review of serotonin syndrome, ecstasy (MDMA) and the use of other serotonergic substances: hierarchy of risk.

Growth of the antidepressant market and widespread use of the illicit drug ecstasy (methylenedioxymethamphetamine; MDMA) creates a need to delineate the potential harms associated with the concomitant use of ecstasy and serotonergic pharmaceutical drugs. One such harm is serotonin syndrome. The study aimed to synthesize the risk of serotonin syndrome associated with the concomitant use of ecstasy and other serotonergic substances in a clinically relevant hierarchy for psychiatrists and other medical practitioners. An extensive online database search was carried out of the literature on serotonin syndrome, in relation to illicit drugs and simultaneous use of other substances. Numerous licit and illicit substances implicated in serotonin syndrome, when used with ecstasy, have potential for increased toxicity and are presented in a resulting hierarchy of risk. Substances that inhibit serotonin re-uptake are less likely to lead to life-threatening elevations in serotonin when used with ecstasy. High doses or repeated use of stimulants such as methamphetamine and cocaine with ecstasy increase the risk of serotonin syndrome; as does the use of pharmaceutical amphetamine and ecstasy. Serotonin precursors also influence the course of serotonin syndrome when used with ecstasy. Substances that inhibit monoamine oxidase are most likely to lead to serious increases in serotonin when used with ecstasy. Findings highlight the importance of screening for the use of ecstasy and other serotonergic substances when prescribing antidepressant drugs.

Adolescent substance use and educational attainment: An integrative data analysis comparing cannabis and alcohol from three Australasian cohorts

BACKGROUND The relative contributions of cannabis and alcohol use to educational outcomes are unclear. We examined the extent to which adolescent cannabis or alcohol use predicts educational attainment in emerging adulthood. METHODS Participant-level data were integrated from three longitudinal studies from Australia and New Zealand (Australian Temperament Project, Christchurch Health and Development Study, and Victorian Adolescent Health Cohort Study). The number of participants varied by analysis (N=2179-3678) and were assessed on multiple occasions between ages 13 and 25. We described the association between frequency of cannabis or alcohol use prior to age 17 and high school non-completion, university non-enrolment, and degree non-attainment by age 25. Two other measures of alcohol use in adolescence were also examined. RESULTS After covariate adjustment using a propensity score approach, adolescent cannabis use (weekly+) was associated with 1½ to two-fold increases in the odds of high school non-completion (OR=1.60, 95% CI=1.09-2.35), university non-enrolment (OR=1.51, 95% CI=1.06-2.13), and degree non-attainment (OR=1.96, 95% CI=1.36-2.81). In contrast, adjusted associations for all measures of adolescent alcohol use were inconsistent and weaker. Attributable risk estimates indicated adolescent cannabis use accounted for a greater proportion of the overall rate of non-progression with formal education than adolescent alcohol use. CONCLUSIONS Findings are important to the debate about the relative harms of cannabis and alcohol use. Adolescent cannabis use is a better marker of lower educational attainment than adolescent alcohol use and identifies an important target population for preventive intervention.

Factors associated with variability and stability of cannabis use in young adulthood

BACKGROUND This study investigated the factors associated with initiating cannabis use, reverting to cannabis use and remaining a cannabis user in young adulthood. This is an important area of research as the risk for cannabis initiation is extending beyond adolescence and opportunities to influence cannabis use pathways can emerge throughout the life-course. METHODS A large, community-based sample was followed prospectively. Data from two successive waves (mean age 23 years and 27 years respectively) of the Path Through Life Study (PATH) were analysed (n=2045). The longitudinal design enabled change in cannabis use in young adulthood to be predicted based on factors assessed approximately four years prior. RESULTS An environment of licit drug use was strongly associated with initiating cannabis use (tobacco: OR=4.98, 95%CI: 2.31-10.76) and reverting to cannabis use in young adulthood (alcohol: OR=2.13, 95%CI: 1.42-3.19). Greater fun seeking was found to orientate people towards initiating cannabis use in young adulthood (OR=1.17, 95%CI: 1.04-1.30). Higher psychoticism increased the odds of remaining a cannabis user (OR=1.19, 95%CI: 1.07-1.33). Religious involvement was protective of cannabis initiation (OR=0.89, 95%CI: 0.83-0.95). Early childhood factors did not influence the pattern of cannabis use in young adulthood. CONCLUSIONS The findings make an important contribution to the development of prevention and intervention strategies for young adults by drawing attention to specific areas of risk and protection.

Residential detoxification: essential for marginalised, severely alcohol- and drug-dependent individuals

INTRODUCTION AND AIMS In an era of health care rationalisation, residential detoxification services catering for drug- and alcohol-dependent homeless people are being closed. The principal findings of a recent evaluation of a non-medicated residential detoxification service are presented. The aims were to describe the characteristics of residents, their experience of admission, rates of withdrawal completion, referral patterns, staff and key informant perceptions of the service and its role within the wider treatment system. DESIGN AND METHODS A process evaluation was utilised incorporating interviews with residents (n = 80) and key informants (n = 13); a survey of all service staff (n = 10); and demographic and clinical data for all residents (n = 392) admitted over one calendar year. Results. Residents were heavily substance-dependent and marginalised, with many exhibiting substantial mental and physical health impairments. Polydrug use and frequent prior engagement with drug and alcohol services were common. The majority completed withdrawal and were referred to further treatment. Residents who presented for heroin and other opiate withdrawal were more likely than other residents to leave before completing treatment (odds ratio 2.47, 95% confidence interval 1.48 - 4.15). Information from key informants, service staff and residents converged in underscoring the important role performed by the service. DISCUSSION AND CONCLUSION Out-patient detoxification for homeless and severely drug- and alcohol-dependent populations is unrealistic. For this group, access to residential detoxification is vital as it provides an environment where potentially serious medical and psychological complications can be managed. There continues to be a clear role for supervised withdrawal in such a setting.

How can data harmonisation benefit mental health research? An example of The Cannabis Cohorts Research Consortium

Peter Butterworth is supported by ARC Future Fellowship (FT130101444). Louisa Degenhardt is supported by an NHMRC Principal Research Fellowship (APP1041742). Delyse Hutchinson is supported by a ViceChancellor’s Postdoctoral Fellowship from the University of New South Wales. Richard P Mattick is supported by an NHMRC Principal Research Fellowship (APP1045318). Craig Olsson is supported by an Australian Research Council Principal Research Fellowship (DP 1311459). George Patton is supported by an NHMRC Senior Principal Research Fellowship (APP1019887).

Uptake of wheel-filtration among clients of a supervised injecting facility: Can structured education work?: Wheel-filtration uptake among SIF clients

INTRODUCTION AND AIMS Wheel-filtration of pharmaceutical opioid tablets is a recognised harm reduction strategy, but uptake of the practice among people who inject drugs is low. The study aimed to: (i) examine perceptions of filtration practices; (ii) provide structured education on wheel-filtration; and (iii) assess uptake of the practice. DESIGN AND METHODS Frequent opioid tablet injectors (n = 30) attending a supervised injecting facility in Sydney, Australia, received hands-on instruction on wheel-filtration based on recommended practice. Pre-education, post-education and follow-up questionnaires were administered. RESULTS Wheel-filtration was generally regarded as better than cotton-filtration (the typical method) in terms of perceived effects on health, ease of use and overall drug effect. Sixty-eight percent of those who said they would try wheel-filtration after the education had actually done so. Of those who usually used cotton-filtration, over half (60%) had used wheel-filtration two weeks later. DISCUSSION AND CONCLUSIONS Uptake of safer preparation methods for pharmaceutical opioid tablets increases after structured education in wheel-filtration. Findings suggest that SIFs are an effective site for this kind of education. Supervised injecting facility workers are uniquely positioned to provide harm reduction education at the time of injection. [Steele M, Silins E, Flaherty I, Hiley S, van Breda N, Jauncey M. Uptake of wheel-filtration among clients of a supervised injecting facility: Can structured education work? Drug Alcohol Rev 2018;37:116-120].

Rethinking dose-response effects of cannabis use in adolescence - Authors' reply.

www.thelancet.com/psychiatry Vol 1 November 2014 417 Authors’ reply We would like to thank Tom Freeman and Amanda Reiman and colleagues for their comments. Freeman and colleagues suggest the possibility that the associations between extent of early cannabis use and later outcomes reported in our Article were non-linear. They note that fi ndings for individuals reporting daily use tend to show lower rates of problems than do those reporting weekly use. It is our view that these apparent non-linearities are due to the small number of daily users, introducing some uncertainty into the specification of point estimates. Surely there are no statistical grounds for believing the association is nonlinear. We would note that the authors considered the classification of the extent of cannabis use, and whether the estimates for daily use should be presented was debated because of the small numbers included. In the end, we decided to present daily users as a separate group to display the available data. However, because of the small numbers included, strong inferences clearly cannot be drawn around the prognosis of the daily user group. case, poverty, familial chaos, racism, and trauma often vary with both early and regular cannabis use and the outcomes described in this study. Controlling for the characteristics of the participant’s life in the years leading up to the initiation of cannabis use would strengthen this research. In view of the fact that regular cannabis use before the age of 17 years is rare (7% of high-school seniors in the USA), these individuals probably have experiences that diff er from the 93% of their peers who are not using cannabis regularly at that age. Additionally, the study does not address the role that marijuana prohibition has as an environmental factor that shapes life consequences for cannabis users. Penalties for marijuana possession in adolescence might not include jail time but frequently include suspension or expulsion from school, removal from team sports, and denial of access to peer groups. These outcomes all aff ect future drug use. Participants in this study were probably marginalised from their educational experience because of their cannabis use, which would perpetuate the negative outcomes. The absence of third factor theory caveats in media coverage of the study, including consideration of marijuana policy, might lead readers to conclude that cannabis legalisation will result in increased rates of adolescent use that would turn into the negative outcomes described. There is no evidence that the legalisation or decriminalisation of cannabis results in increased use rates in teenagers, and some have suggested the opposite. For example, a compliance check in the cities of Denver and Pueblo Colorado, using underage decoys, found not one cannabis outlet among those tested who was willing to sell to a minor. No one is suggesting that cannabis use is suited for young people, rather that regulation is a more effective tool at preventing underage use than prohibition.