OBJECTIVE: The objective of this dissertation is to test three hypotheses: 1) there is no association linking a history of any cannabis smoking (including early-onset cannabis use, EOCU) with school entry; 2) there is no association between the entry into primary school and EOCU; and 3) there is no association between EOCU and completing each of the educational milestones beyond primary school: starting but not finishing secondary school, starting tertiary school, and starting but not finishing tertiary school.METHODS: The estimates for this work are based on cross-sectional national probability sample survey data from 16 countries participating in the World Mental Health Surveys Consortium, 2002-2007. There were 41695 participants, of whom 3113 did not enter into the school trajectory, and 6020 had used cannabis, including 2187 who started using before age 17 (EOCU). The methods included unadjusted and adjusted conditional logistic regression, unconditional logistic regression, and meta-analytic methods for estimation. The sampling plan complexity was taken into account (e.g., using weights based on sample selection probabilities), with Taylor series linearization methods for variance estimation as needed for non-independent observations (e.g., multiple households within sampled neighborhoods).RESULTS: After adjusting by sociodemographic covariates such as sex and age, there was no association between cannabis use trajectory variables and school entry (p > 0.05). Based on the area-matched conditional logistic regression model after statistical adjustment for eighteen meaningful covariates, there was an association between early-onset cannabis smoking and later secondary school failure (meta-analytic odds ratio estimate of 1.9; 95% CI = 1.3, 2.7). This result remained consistent when using the unconditional form of multiple logistic regression and the same set of covariates. Concerning failure to enter post-secondary schooling once secondary schooling has been completed, a departure from the null association was found in area-matched analyses with full covariate terms added to the conditional logistic regression model (meta-analytic odds ratio estimate of 1.4; 95% CI = 1.1, 1.7). However, the unconditional form of multiple logistic regression and the resulting meta-analytic odds ratio of 1.2 did not help to confirm those results (95% CI = 0.8, 1.8). Similar inconsistent results were found in estimating the association between EOCU and completing tertiary school once it started. There was evidence of cross-country variations in the association size for all three educational milestones.CONCLUSIONS: Cannabis use is rare during the years before one enters primary school. This dissertation's estimates suggest that failure to start school was not predictive of later cannabis smoking. Once schooling starts, there is a consistent finding that those with early-onset cannabis use are more likely not to complete secondary school. There is an association, although somewhat inconsistent, between early-onset cannabis use and failing to achieve the schooling milestones after completing secondary school. In future research, replications will strengthen the evidence and create a more solid evidence base about the underlying mechanisms that link early-onset cannabis smoking with disruption of schooling trajectories. That evidence base may create a foundation for future prevention and control activities at the intersection of public health and public education.
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