Early and Frequent Teen Cannabis Use Linked to 51% More Mental Health and 86% More Physical Health Visits by Age 23

Three adolescent cannabis patterns were identified: nonuse (60%), late-onset after 15 (20%), and early/frequent before 15 (20%). Early/frequent users had 51% higher odds of mental health care (OR 1.51), 57% higher odds of common mental disorder care (OR 1.57), and 86% higher odds of physical health care (OR 1.86) compared to nonusers. Late-onset users showed increased physical but not mental health care utilization.

Population-based birth cohort from the Quebec Longitudinal Study of Child Development linked to administrative medical databases. Self-reported cannabis use at ages 12, 13, 15, and 17. Medical care utilization tracked from ages 18-23. Analyses adjusted for 32 individual, family, and community-level confounders measured from birth to age 12 using overlap weights.

This is among the strongest evidence linking adolescent cannabis patterns to concrete healthcare outcomes. By adjusting for 32 confounders measured before cannabis exposure began, it addresses the concern that pre-existing factors rather than cannabis itself drive the association.

The distinction between early/frequent and late-onset patterns is critical for policy. Late-onset users (starting after 15) did not show excess mental health care utilization, suggesting that delaying initiation may be as important as preventing use entirely.

Canadian birth cohort may not generalize to other populations. Medical care utilization reflects healthcare-seeking behavior, not just health status. Self-reported cannabis use may be underreported. Administrative data captures diagnoses given during visits but may miss undiagnosed conditions.