14 February 1997
We performed a cross-sectional comparison of the baseline neuropsychologic performance of 107 injecting drug users and 230 homosexual men participating in two longitudinal studies. Cognitive tests measured attention, memory and psychomotor speed. Using multiple regression modelling, the analysis adjusted for age, IQ score, race, six-month history of alcohol, cocaine, opiates and marijuana use, HIV serostatus and CD4+ lymphocyte count. Injecting drug users showed significantly poorer scores in all neuropsychologic tests in the univariate analysis. However, once adjusted for age, IQ score and race, only Rey Complex Figure tests were significantly worse among injecting drug users. These data indicate that age and IQ score rather than risk group account primarily for the differences in the cognitive performance, regardless of serostatus and CD4+ count.