Associations between adolescent cannabis use frequency and adult brain structure: A prospective study of boys followed to adulthood

Drug Alcohol Depend. 2019 Sep 1;202:191-199. doi: 10.1016/j.drugalcdep.2019.05.012. Epub 2019 Jul 19.


Background: Few studies have tested the hypothesis that adolescent cannabis users show structural brain alterations in adulthood. The present study tested associations between prospectively-assessed trajectories of adolescent cannabis use and adult brain structure in a sample of boys followed to adulthood.

Methods: Data came from the Pittsburgh Youth Study - a longitudinal study of ˜1000 boys. Boys completed self-reports of cannabis use annually from age 13-19, and latent class growth analysis was used to identify different trajectories of adolescent cannabis use. Once adolescent cannabis trajectories were identified, boys were classified into their most likely cannabis trajectory. A subset of boys (n = 181) subsequently underwent structural neuroimaging in adulthood, when they were between 30-36 years old on average. For this subset, we grouped participants according to their classified adolescent cannabis trajectory and tested whether these groups showed differences in adult brain structure in 14 a priori regions of interest, including six subcortical (volume only: amygdala, hippocampus, nucleus accumbens, caudate, putamen, and pallidum) and eight cortical regions (volume and thickness: superior frontal gyrus; caudal and rostral middle frontal gyrus; inferior frontal gyrus, separated into pars opercularis, pars triangularis, and pars orbitalis; lateral and medial orbitofrontal gyrus).

Results: We identified four adolescent cannabis trajectories: non-users/infrequent users, desisters, escalators, and chronic-relatively frequent users. Boys in different trajectory subgroups did not differ on adult brain structure in any subcortical or cortical region of interest.

Conclusions: Adolescent cannabis use is not associated with structural brain differences in adulthood.

Keywords: Adolescent; Brain structure; Cannabis; Magnetic resonance imaging.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Brain / diagnostic imaging
  • Brain / growth & development
  • Brain / pathology*
  • Humans
  • Latent Class Analysis
  • Longitudinal Studies
  • Magnetic Resonance Imaging / methods
  • Male
  • Marijuana Use / pathology*
  • Neuroimaging
  • Prospective Studies
  • Young Adult