Polydrug Abusers Display Impaired Discrimination-Reversal Learning in a Model
of Behavioral Control
Mark T. Fillmore*
Craig R. Rush
University of Kentucky, USA
* To whom correspondence should be addressed.
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Abstract |
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Long-term cocaine and alcohol use is associated with neuropsychological
impairments that implicate poor inhibitory mechanisms of behavioural control. This study
tested acquisition and discrimination-reversal learning in a group of polydrug users (n
= 20) with a history of cocaine and heavy alcohol use and a group of age-matched
controls (n = 20). A cued go/nogo task measured subjects' ability to learn
stimulus-response associations that involved the quick activation and sudden inhibition
of responses. Compared with controls, drug users displayed similar acquisition, but
impaired discrimination-reversal learning of both inhibitory and activational responses.
The results suggest that some drug-related neuropsychological deficits might reflect
specific impairments of the ability to inhibit interference from prior learning. The
findings contribute to growing evidence that suggests cocaine and alcohol use could
produce broad inhibitory impairments that increase the risk for learning deficits and
poor impulse control.
Key Words:
cocaine, alcohol, discrimination-reversal learning, inhibition
