Cognitive impairment associated with cocaine use: The role of co-existent alcohol abuse/dependence

Cocaine abuse has been reported as leading to impaired cognitive function. However, cocaine abusers commonly also abuse alcohol, which can itself produce cognitive impairment. This study, therefore, aimed to examine the potential confounding effect of alcohol abuse on neuropsychological test performance in cocaine and alcohol abusing individuals, comparing them with individuals who abused alcohol alone and non-abusing controls.

Nineteen cocaine abusers who also met DSM-IV criteria for alcohol abuse/dependence (14 m, 5f; mean age 38.65 ± 3.83) and 20 matched individuals who met criteria for alcohol abuse/dependence alone (12 m, 8f; mean age 38.19 ± 4.82) were administered a battery of neuropsychological tests covering executive function, memory, language and visual/visuospatial function after two to four weeks of abstinence. Nineteen matched healthy controls (8 m, 11f; mean age 37.01 ± 5.98) were also tested.

Both the cocaine + alcohol group and the alcohol group performed significantly more poorly than the healthy controls on the executive (ESs 2.13 and 2.57) and memory tests (ESs 0.58 and 1.06). The findings were similar for language (ESs 0.92 and 1.69), where the cocaine + alcohol abusers additionally performed significantly better than the alcohol abusers. Both patient groups were impaired on two of the five tests of visual/visuospatial function, with better performance by the cocaine + alcohol group on one of them.

Chronic cocaine abuse does not appear from this study to be associated with cognitive impairment over and above that which can be attributed to co-existent alcohol abuse.