Increased picture-word interference in chronic and recreational users of cocaine.

OBJECTIVE: The correct production of speech depends on the effective use of inhibitory control. Cocaine abuse has been linked to impaired inhibition in the verbal and nonverbal domains. The aim of this study was to evaluate the possible impairment of the inhibitory control process engaged in the production of language among chronic cocaine users, both in rehabilitation and recreational contexts.

METHOD: Researchers obtained an index of semantic interference from a picture-word task performed by chronic cocaine users in rehabilitation (Experiment 1) and recreational cocaine polydrug users (Experiment 2). Cocaine users in both groups were matched for age and intelligence with cocaine-free health controls. Performance on the picture-word task was analyzed by repeated-measures analyses of variance.

RESULTS: Both groups of cocaine users showed significantly more semantic interference than their respective cocaine-free control group. These results suggest a deficit in the ability to inhibit interfering information.

CONCLUSIONS: The present findings suggest that cocaine use, even at recreational levels, is associated with specific impairments in the inhibitory mechanism that reduces the activation of overt competing responses in language production. This impairment results in the inefficient avoidance of irrelevant information, inducing errors and slower responses during the production of spoken language.