Cannabis use is associated with changes in psychological and functional well-being during young adulthood: evidence from self-reports and hair analyses.
Psychological medicine August 26, 2025 Lydia Johnson-Ferguson, Michelle Loher, Laura Bechtiger et al. 2 citations
Frequent cannabis use in young adulthood predicts increases in psychotic-like experiences, internalizing symptoms, aggression, problematic substance use, and higher odds of not being in employment, education, or training, along with decreased general well-being from ages 20 to 24. These associations held whether cannabis exposure was measured by self-reported frequency or by hair THC concentrations, and effect sizes were small. Composite measures combining self-reports and hair data were no more informative than either source alone. The findings come from a community sample of 863 young adults, with 150 reporting weekly-to-daily use and 110 having detectable cannabis in hair at age 20.