[Review: executive functioning and cannabis use].Braz J Psychiatry 2008; 30(1):69-76BJ
Cannabis is the most used illicit drug worldwide, however only a few studies have examined cognitive deficits related to its use. Clinical manifestations associated with those deficits include a motivational syndrome, impairment in cognitive flexibility, inattention, deficits in abstract reasoning and concept formation, aspects intimately related to the executive functions, which potentially exert a central role in substance dependence. The objective was to make a review about consequences of cannabis use in executive functioning.
This review was carried out on reports drawn from MedLine, SciELO, and Lilacs.
In studies investigating acute use effects, higher doses of tetrahydrocannabinol are associated to impairments in performance of nonsevere users in planning and control impulse tasks. However, chronic cannabis users do not show those impairments. Although demonstration of residual effects of cannabis in the executive functioning is controversial, persistent deficits seem to be present at least in a subgroup of chronic users after 28 days of abstinence.
The neuropsychological studies found did not have as a main aim the evaluation of executive functioning. A criterial selection of standardized neuropsychological tests, more appropriate study designs as well as concomitant investigations with structural and functional neuroimaging techniques may improve the understanding of eventual neurotoxicity associated with cannabis use.