Three-Year Follow-Up: Cannabis Use Declined in Aboriginal Communities But Users Had More Hallucinations and Suicidal Thoughts

Longitudinal cohort study with 3-year follow-up. Randomly selected sample (n=161) and opportunistic sample (n=104) from Aboriginal communities in Arnhem Land, NT, Australia. Cannabis and substance use assessed by combining proxy assessments from Aboriginal health workers, medical records, and interview data. Changes analyzed using McNemar's test and Wilcoxon signed rank test.

This is one of very few longitudinal studies of cannabis use in an indigenous population. The finding that persistent use was associated with hallucinations, suicidal thoughts, and imprisonment underscores the real-world consequences of heavy cannabis use in a vulnerable population, while the overall decline in use suggests that community-level interventions can be effective.

Cannabis has been identified as a major health concern in some remote Australian Aboriginal communities. This study documented both the harms associated with continued use and the potential for community-level changes to reduce cannabis use. The reduction over three years, attributed partly to supply control, suggests that policy interventions can affect use patterns even in remote communities.

Relatively small sample from a specific remote population, limiting generalizability. Cannabis use was assessed through combined proxy, medical, and self-report methods rather than biological testing. The observational design cannot determine whether cannabis caused the psychiatric symptoms or shared risk factors explain both. The decline in use may reflect specific local factors not applicable elsewhere.