Cognition and immune function in HIV-1 infection

OBJECTIVES: To determine (1) whether there were differences in cognition between HIV-1-seropositive and HIV-1-seronegative homosexual men and (2), if so, whether these differences could be explained by the degree of immunosuppression [i.e., CD4 cell count and immunoglobulin A (IgA) levels]. DESIGN: A cross-sectional design was used to compare 66 HIV-1-seropositives (Centers for Disease Control stages II and III, n = 56; stages IVA and IVC-2, n = 10) and 37 HIV-1-seronegatives. The HIV-1-seropositives were classified into three immune groups based on their CD4 cell count (x 10(6)/l) and serum IgA level (mg/dl): (1) moderate [(n = 35) CD4 greater than 400, IgA less than 300]; (2) mixed [(n = 22) either CD4 greater than 400 and IgA greater than 300 or CD4 less than 400 and IgA less than 300] and (3) poor [(n = 9) CD4 less than 400, IgA greater than 300]. HIV-1-seronegatives formed the 'good' immune group (CD4 greater than 400 and IgA less than 300). METHODS: The four groups were compared on tests of verbal and visual memory, information-processing speeds, visuospatial skills, language processes, attention, psychomotor reaction time, and mental status. Factors other than HIV-1 sero-status that can influence cognitive performance were tested as covariates. RESULTS: HIV-1-seropositives had slower information-processing speeds and decreased verbal and visual memory, compared with HIV-1-seronegatives. These differences in cognition were not due to differential immunosuppression or to clinical status among the HIV-1-seropositives. CONCLUSIONS: Cognitive alterations occur in HIV-1-infected individuals before AIDS and appear to be independent of clinical status and degree of immunosuppression as measured by CD4 cell count and IgA levels.