Effects of immunosuppression and disease severity upon neuropsychological function in HIV infection.

Effects of immunosuppression and illness severity upon neuropsychological function were assessed in a group of homosexual men with AIDS across 6 months. Participants included 62 who were seronegative (HIV-), 74 asymptomatic seropositives (HIV+A), 31 symptomatic seropositives (HIV+S), 23 with AIDS defining illnesses (AIDS-DI), and 10 who were diagnosed with AIDS solely on the basis of CD4+ levels falling below 200 /mm3 (AIDS-CD4). Groups were equivalent in age, education, and IQ. None were drug users, and none experienced a change in disease status across the 6-month inter-test interval. There was little evidence of cognitive decline across time. Nonetheless, after collapsing across time intervals, the AIDS-DI group had worse new-learning than all other groups. Additionally, the AIDS-DI demonstrated a greater number of impaired performances than the other participant groups. The data suggest that cognitive impairment in AIDS is unlikely due to independent contributions of immunosuppression and illness. Rather neurobehavioral deficits are more likely attributable to a combination of the two.