Cannabis Use and Disorder Transitions Among a Mixed Community Sample of At-Risk Adolescents and Adults: A Prospective New Zealand Study

ABSTRACT

The trajectories of cannabis use disorder (CUD) require more comprehensive delineation to expedite recognition of incubating dependence among high-risk users. This study examined baseline cannabis use and CUD over 12 months using DSM-IV/ICD10 diagnoses to distinguish transition groups.

In a prospective naturalistic design, 194 heterogeneous cannabis users (128 adolescents, 66 adults) aged 13-61 years were voluntarily recruited and assessed at baseline, and then re-assessed 12-months later.

Most participants met criteria for a baseline CUD (70% dependence, 20% abuse), 12 adolescents were 'diagnostic orphans', and 5 symptom-free. At follow-up, 25% adolescents reported using less, 6% the same level, and 69% using more cannabis. Significantly increased symptoms and dependence severity were reported, with no adolescent/adult differences evident. Three diagnostic transition groups were identified. While 84% adolescents (n=108) remained stable, 5% (n=7) had improved, 10% (n=13) had deteriorated. ‘Deteriorators’ scored significantly higher than ‘improvers’ on cannabis use, symptoms, and dependence severity measures. A subjective loss of control over cannabis use was among the earliest DSM-IV features among younger users on a trajectory towards dependence. Most participants (79%) anticipated difficulty trying to reduce/quit their use.

Younger adolescents can rapidly develop cannabis dependence, reporting similar and equally severe symptoms as longer-term adult users.

Impaired control over use occurs early in trajectories towards dependence. The seeming intractability of problematic cannabis use calls for concerted cannabis screening and early intervention (SEI) efforts at an earlier age to avert or reduce harmful consequences of cannabis use in the community.

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