Incidental Learning and Memory Deficits on a Computerized Symbol-Digit Modalities Test in Adults with HIV/AIDS.

Objective: Incidental learning and memory, as well as processing speed, were examined in human immunodeficiency virus (HIV)-positive adults and a seronegative control group.

Methods: Participants completed a computerized Symbol-Digit Modalities Test (cSDMT) with two blocked conditions: a set of trials with the standard symbol-digit pairings and the second set with a rearranged symbol-digit pairings.

Results: HIV-positive adults showed slower overall reaction time compared to the HIV-negative group. More importantly, the most cognitively impaired HIV-positive group showed no interference in the rearranged set of symbol-digit pairings from the standard pairings on the cSDMT.

Conclusion: The relative slowing, or interference, in the HIV-negative group and two HIV-positive groups (unimpaired and impaired) was quite large (between 122 and 131 ms). We argue that the lack of such relative slowing in the most cognitively impaired HIV-positive group indicates a deficit in incidental learning and memory.