Effect of Aging and Human Immunodeficiency Virus Infection on Cognitive Abilities

OBJECTIVES: To explore the combined effects of aging and human immunodeficiency virus (HIV) infection on cognitive decay. DESIGN: Cross-sectional, single-cohort study. SETTING: Institute of Clinical Infectious Diseases, Catholic University of the Sacred Heart, Rome, Italy. PARTICIPANTS: One hundred fifty-three asymptomatic HIV-positive (HIV+) outpatients (20% aged ≥ 60) and an age- and education-matched control population of 39 HIV-negative individuals. MEASUREMENTS: A neuropsychological investigation was conducted to compare four groups of participants classified on the basis of HIV serostatus and age (<60 vs ≥ 60). The effects of age and HIV infection on neuropsychological performance were analyzed using a two-by-two factorial analysis of variance. Demographic and clinical variables associated with neuropsychological performance were identified using linear regression analysis in the HIV+ population. RESULTS: HIV infection and aging had significant negative effects on cognitive performance, but no significant interaction was observed between these two factors. Although older HIV+ participants had worse cognitive performance, they showed no distinct cognitive pattern from younger HIV+ participants. Moreover, younger HIV+ participants' performance on memory tasks was qualitatively and quantitatively comparable with that of older HIV- participants, despite the dramatic age difference. CONCLUSION: Aging and HIV might be additive factors in the expression of cognitive decline. As the HIV+ population ages, routine neuropsychological examinations could help clinicians better understand and manage the expression of cognitive impairment.