Neuropsychological test performance in the acquired immunodeficiency syndrome: Independent effects of diagnostic group on functioning

Individuals infected with the acquired immunodeficiency syndrome (AIDS) are at risk for developing cognitive impairment. The extent to which the impai rment represents the results of a single factor accounting for a wide degre e of cognitive dysfunction, or is the result of the combined effects of mul tiple factors, has not been determined. In the present study, we analyzed d ata from 134 patients with AIDS and 105 HIV- controls using a recently deve loped analytical procedure. The results revealed that, by and large, the te st variables shared a significant amount of variance related to disease sta tus. Hence the AIDS-related influences on cognition are shared and thus can not be considered independent. Two tests, Digit Symbol Substitution, and th e primacy measure of verbal free recall, had a direct relationship with the group variable (AIDS vs. controls). These results suggest that a single fa ctor is sufficient to account for a large proportion of the AIDS-related va riance on a wide variety of neuropsychological tests.