Effects of Chronic Cocaine Abuse on Verbal Learning and Memory

The purpose of this study was to determine the existence and nature of verbal memory deficits in a group of chronic cocaine abusers. Functional impairment in a control group of recovering alcoholics was also examined. Participants were selected from groups of volunteers enrolled in various drug treatment programs at the Veterans' Hospital in Hampton, Virginia. All participants were at least 30 days abstinent at the time of testing. Twelve cocaine abusers with a mean use time of 10 years served as the experimental group. Ten alcoholics with a mean use time of 25 years served as the control group. Participants were given a battery of neuropsychological tests to assess attentional abilities, immediate and delayed free recall for word lists and stories, recognition ability, ability to profit from memory cues, and learning strategies. Both groups of substance abusers showed normal performance on tests of attentional abilities. Cocaine abusers showed decreased learning efficiency of word lists and had difficulty with immediate and delayed free recall of word lists and stories. In addition, cocaine abusers did not use the expected amount of semantic (meaning-based) processing in their learning of word lists. Both groups displayed normal performance on recognition testing and profited from memory cues. Overall, cocaine abusers showed verbal learning impairment that can be attributed to reduced learning efficiency and poor learning strategies. Contrary to previous research, attentional impairments were not found in this study, possibly due to the relatively long abstinence times of participants in this study. It is possible that the types of impairments shown by cocaine abusers could be mitigated through training in the use of more efficient learning strategies, such as semantic processing and the use of memory aids. Future studies in this area might address the implementation and effectiveness of this type of training for cocaine abusers.