Normative data for the neuropsychological evaluation of intravenous drug users

BACKGROUND: There are many recent epidemiological studies that find that intravenous drug users' (IDU's) performance in several measures of neuropsychological function are not the same than that of the general population, whether they are seropositive to HIV-1 infection or not. Consequently, it has been stated the need to establish appropriate norms for this population. The purpose of this study is to provide normative data on a battery of neuropsychological tests from a IDU group. SUBJECTS AND METHODS: This report provide normative data from a group of 116 IDU, on a battery of neuropsychological tests stratified by age group (mean = 30.9; SD = 4.5), and educational level (mean = 8; SD = 2.4). Comparisons between the means of the different groups according to age and education, and also with respect to sex are made. The analysis includes estimation of partial correlations between neuropsychological test scores and age and education. RESULTS: The analysis demonstrates that education is an important determinant of performance for most of these tests, while there are no differences in performance between the two age-groups. With respect to sex, females out-performed men on a measure of motor speed and coordination. CONCLUSIONS: This report provides norms that may be of use as a reference for clinical evaluation and research in drug user populations. It also emphasizes the need to establish normative data controlling for variables like educational level, from a population with special characteristics such as IDU population.