whether cannabis use (ever used; frequency of use in ever users) was associated with regional gray matter volume in any of these regions. Third, we examined whether associations between genotype and regional brain volume persisted after controlling for cannabis use. All DNS analyses controlled for sex and age; analyses on regional brain volume also controlled for total intracranial volume (ICV), while analyses including genotype additionally included the first three principal components of ancestry. All non-imaging analyses and group comparisons were conducted using the R (3.1.2) ‘Stats’ package.
