When Household Members Quit Cannabis, Teens' Mental Health Improved

Longitudinal cohort study using ABCD Study waves 2 and 3. Included adolescents ages 10–13 with household cannabis use at wave 2. Cessation defined as absence of household member cannabis use at wave 3. Propensity score matching for demographic and psychometric confounders. Outcomes: Child Behavior Checklist (internalizing, externalizing), Prodromal Questionnaire-Brief (psychotic-like experiences). Mediators: Family Environment subscale (conflict), Sleep Disturbance Scale for Children.

Most cannabis mental health research focuses on the user themselves. This study asks a different question: what happens to the children in the household? The finding that household cessation improves teen mental health — mediated through reduced family conflict and better sleep — suggests that cannabis use affects families, not just individuals.

This family-level perspective connects to the individual adolescent research. The expectancy trajectories study (RTHC-00272) found that family dynamics shaped cannabis attitudes. The discrimination-to-intention study (RTHC-00264) showed environmental factors influence cannabis risk. This study adds that household substance use — and its cessation — directly affects teen mental health through the home environment. The sleep finding links to the cannabis-sleep research (RTHC-00281, RTHC-00012): if household cannabis use disrupts teen sleep (through secondhand exposure, household disruption, or other mechanisms), cessation would improve both sleep and the mental health outcomes that depend on it.

Observational design — household cessation may coincide with other positive changes (employment, relationship improvement, reduced stress) that independently benefit teen mental health. Household cannabis use was assessed by report, which may be inaccurate. Cannot determine whether effects are from secondhand exposure, household environment, genetic factors, or some combination. Two-wave comparison limits trajectory analysis.