“It is unclear whether the subtle cognitive and brain differences observed in young cannabis users might be larger in midlife and older adult cannabis users with longer histories of use,” Madeline H.
Participants were assessed for cannabis use and dependence at ages 18, 21, 26, 32, 38 and 45, with IQ gauged at ages 7, 9, 11 and 45 years.
Cognitive deficits among the study group could not be explained by habitual use of tobacco, alcohol or other illicit drugs; socioeconomic status in younger years or family history of substance dependence.