Attention and memory in illicit amphetamine users: comparison with non-drug-using controls.

The purpose of this study was to clarify the extent of neuropsychological impairment previously found among amphetamine users (McKetin and Mattick, 1997) by comparing them with a non-drug-using control group. Amphetamine users who were classified as low dependence (n = 15) or high dependence (n = 11) according to the severity of dependence scale (SDS) were compared to non-drug-using control subjects (n = 9) on indices of the Wechsler Memory Scale-Revised (WMS-R). Dependent amphetamine users (high dependence group) performed approximately one half of a standard deviation worse than controls on the verbal memory, attention/concentration and delayed recall indices of the WMS-R but amphetamine users who were less dependent (low dependence group) showed no impairment.