Recreational cocaine polydrug use impairs cognitive flexibility but not working memory.

Rationale: Chronic use of cocaine is associated with dysfunctions in frontal brain regions and dopamine D2 receptors, with poorer mental flexibility and a reduced ability to inhibit manual and attentional responses. Little is known, however, about cognitive impairments in the upcoming type of recreational cocaine polydrug user (1-4 g monthly consumption). Objective: We studied whether recreational cocaine polydrug users, who do not meet the criteria for abuse or dependence, showed impairments in working memory (WM) and cognitive flexibility. Methods: Controls and recreational cocaine polydrug users (who abstained from cocaine and other substances more than 1 week) were matched by sex, age, alcohol consumption, and IQ (Raven's Standard Progressive Matrices). Groups were tested by using two cognitive tasks measuring cognitive flexibility and three tasks investigating the maintenance and monitoring of information in WM. Results: Recreational cocaine polydrug users performed significantly worse than controls on tasks tapping cognitive flexibility, but show comparable performance in the active maintenance and monitoring of information in WM. Conclusions: The findings suggest that recreational use of cocaine selectively impairs cognitive flexibility but not the maintenance of information in WM. The inability to adjust behavior rapidly and flexibly may have repercussions for daily life activities.