Declarative and procedural memory functioning in abstinent cocaine abusers

Background We determined the nature and recovery of procedural and declarative memory functioning in a cocaine-abusing cohort in the 45-day period following use. Methods Thirty-seven cocaine abusers and 27 control subjects were administered the following memory and mood measures: California Verbal Learning Test, recall of the Rey-Osterrieth Complex Figure 1 Test, Pursuit Rotor Task, and Profile of Mood States at 4 visits (within 72 hours of admission and at 10, 21, and 45 days following abstinence). Results Analysis of performance on the Rey-Osterrieth Complex Figure 1 Test revealed that both groups improved in their recall over repeated administrations, though the control group recalled significantly more of the information than cocaine subjects during the 45-day interval. Results for the California Verbal Learning Test indicated improved learning for both subject groups over time, but no group × time interaction. On the Pursuit Rotor Task, cocaine abusers improved their performance at a faster rate than controls at visit 1. At day 45 (visit 4), cocaine abusers again showed improvement on the Pursuit Rotor Task, whereas controls demonstrated a relative plateau in rate of learning. Conclusions This study documented a lasting detrimental effect on a sensitive nonverbal declarative memory task in cocaine-dependent subjects following abstinence of 45 days. In contrast, abstinence from cocaine during this 45-day period was associated with sustained improvement on a motor learning test in the cocaine abusers relative to controls.