HIV infection and aging independently affect brain function as measured by functional magnetic resonance imaging

Abstract

We investigated the interactions between human immunodeficiency virus (HIV) infection and aging and their effects on brain function demands by means of functional magnetic resonance imaging (fMRI). A multiple-regression model was used to study the association and interaction between fMRI measures, HIV serostatus, and age for 26 HIV-infected subjects and 25 seronegative subjects. Although HIV serostatus and age independently affected fMRI measures, no interaction occurred. Functional brain demands in HIV-positive subjects were equivalent to those of HIV-negative subjects who were 15-20 years older. Frailty parallels between HIV infection and aging could result from continued immunological challenges depleting resources and triggering increased metabolic demands. In the future, fMRI could be a noninvasive biomarker to assess HIV infection in the brain.

Figure 1. Effects of HIV and aging on baseline cerebral blood flow (top), functional changes in cerebral blood flow (middle), and functional changes in the blood oxygen level dependent signal (bottom) in the visual cortex

Both HIV infection and aging led to significant decreases in baseline CBF and functional changes in the blood oxygen level dependent but no interaction was observed. HIV infection and aging also led to significant increases in functional changes in cerebral blood flow but no interaction was observed. The plots include regression lines for baseline each of the functional magnetic resonance imaging (fMRI) measures for HIV+ subjects (triangles) and the HIV− controls (circles). Each of the fMRI measures was log₁₀-transformed, in order to improve normality and homoscedasticity, and then back-transformed to the natural scale.