Neuropsychological functioning in drug abusers.

The present study examined differences in neuropsychological performance among chronic cocaine, alcohol, and polysubstance abusers. A comprehensive neuropsychological battery was completed by 355 incarcerated adult male felons who were classified by DSM-IV criteria into four subgroups: (1) alcohol dependence or abuse (ETOH) (n = 101), (2) cocaine dependence or abuse (COC) (n = 60), (3) polysubstance dependence or abuse (POLY (n = 56), and (4) a group of age and education matched adult male felons with no history of drug abuse (n = 138). Results showed no significant differences in neuropsychological performance between COC and control subjects. However, both the POLY and ETOH groups were found to perform significantly worse on nearly all measures compared to the COC and control groups. Further, analysis of neuropsychological domains showed the POLY group to perform significantly worse compared to the other groups in the areas of short-term memory, long-term memory and visual motor ability. Correlations between neuropsychological performance and length of abstinence from drug use showed the ETOH group to have made the greatest amount of improvement on individual measures and domains. The COC group showed the least amount of improvement, but their performance was not significantly different from controls. Results provide further support for the differential effects of drug use on neuropsychological functioning.