Nora D. Volkow, MD; James M. Swanson, PhD; A. Eden Evins, MD; Lynn E. DeLisi, MD; Madeline H. Meier, PhD;
Raul Gonzalez, PhD; Michael A. P. Bloomfield, MRCPsych; H. Valerie Curran, PhD; Ruben Baler, PhD
Does Cannabis Use Affect Cognitive Capacity?
Cannabis use causes acute impairment of learning and memory, attention, and working memory, 1-3 but it is less clear if cannabis use is associated with enduring neuropsychological impairment. Case-control studies comparing nonintoxicated heavy cannabis users with non users have fairly consistently shown that heavy cannabis users per-form worse on neuropsychological tests. For example, there sults from 2 separate meta-analyses4,5 showed that compared with nonusers, non intoxicated cannabis users perform worse on measures of global neuropsychological function, with effect sizes for specific neuropsy-chological domains (executive functions, attention, learning and memory, motor skills, and verbal abilities) of approximately one-third of a standard deviation or less.