Latency to cannabis dependence mediates the relationship between age at cannabis use initiation and cannabis use outcomes during treatment in men but not women.

Background: Time from first cannabis use to cannabis dependence (latency) may be an important prognostic indicator of cannabis-related problems and treatment outcomes. Gender differences in latency have been found; however, research in this general area is limited. As cannabis use increases and perceived risk declines, a better understanding of how these factors interact in predicting treatment outcomes is critical.
Methods: A secondary data analysis of a randomized, double-blind, placebo-controlled pharmacotherapy trial for cannabis dependence (N = 302) examined the associations between age of cannabis use onset, time to cannabis dependence (latency), and gender on cannabis use during the trial. Mediation analysis tested whether the association between age of onset and cannabis use during the trial was mediated by latency to cannabis dependence differentially for men and women.
Results: Age of use initiation was inversely correlated with latency to dependence prior to treatment [HR(95% CI) = 1.18 (1.06, 1.30); p = .002] and cannabis use during treatment (β=-1.27; SE = 0.37; p < .001). There was a significant mediation effect between age of onset, latency, and cannabis use that varied by gender. Earlier age of onset predicted longer latency, and subsequently, greater cannabis use during the trial in men (21.4% mediated; p < .05), but not women. Other substance use, race, and past psychiatric diagnosis did not predict latency either independently or in interaction models.
Conclusion: Findings support existing evidence that early cannabis use onset is associated with worse outcomes and add new knowledge on the differential associations between age of onset, latency to cannabis dependence, and treatment outcomes for men and women.
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