Heavy drinking and HIV infection are independently associated with damage to the brain’s white matter. As most neuroimaging studies of people living with HIV (PLWH) exclude heavy drinkers, effects of alcohol use on white matter in the context of HIV are not well understood. We examined associations of current alcohol use, HIV status, and clinical characteristics with indices of white matter integrity in PLWH and seronegative controls.
PLWH and controls were recruited from an immunology clinic for a study of alcohol- and HIV-associated brain dysfunction. Participants were categorized as non-drinkers, moderate drinkers, or heavy drinkers per NIH guidelines. Diffusion tensor imaging was used to derive measures of fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). Whole-brain voxelwise analyses were performed using tract-based spatial statistics (TBSS), corrected for multiple comparisons. Confirmatory region-of-interest (ROI) analyses were conducted to probe group differences.
The sample of 108 participants (62 PLWH, 46 controls) averaged 45.2±11.1 years of age and was 42% female. Most PLWH were on antiretroviral therapy (94%) and were virally suppressed (69%). PLWH and controls were matched on rates of heavy drinking, smoking, and other drug use. In voxelwise analyses, heavier alcohol intake was significantly associated with lower FA, higher RD, and lower AD in widespread areas (p’s<.05; Figure 1). ROI analyses confirmed that non-drinkers had higher FA than heavy drinkers in corpus callosum, cingulate gyrus, posterior thalamic radiation, and left external capsule (p's<.05). Non-drinkers had higher FA than moderate drinkers in genu and body of corpus callosum (p's<.05). Moderate drinkers had higher FA than heavy drinkers in body of corpus callosum, posterior thalamic radiation, and left external capsule (p's<.05). Older age extensively predicted lower FA (p<.05). Neither HIV status nor clinical characteristics were associated with FA, and the HIV by drinking group interaction was not significant (p's>.05).
Alcohol use significantly predicted white matter microstructural degradation in this sample of PLWH in care and seronegative controls. Results are consistent with a dose-dependent association of alcohol use with lower white matter microstructural coherence. The overlap between FA and RD maps points to dysmyelination as a possible mechanism. Findings underscore the need to address unhealthy alcohol use in HIV-positive and seronegative individuals.