The development of neurocognitive deficits in those infected with human immunodeficiency virus (HIV) is a significant public health problem. Previous cross-sectional studies show that performance on central auditory tests (CATs) correlates with cognitive test results in those with HIV, but no longitudinal data exist. We have been performing longitudinal assessments of central auditory and cognitive function on a cohort of HIV+ and HIV- individuals in Dar es Salaam, Tanzania to understand how the central auditory system could be used to study and track the progress of central nervous system dysfunction.
The goal of the project was to determine if CATs can track the trajectory of cognitive function over time in those diagnosed with HIV.
Tests of peripheral and central auditory function, as well as cognitive performance, were performed on 382 individuals over the course of 3.5 years. Visits were scheduled every 6 months. CATs included tests of auditory temporal processing (gap detection) and speech perception in noise (Hearing in Noise Test and Triple Digit Test). Cognitive tests included the Montreal Cognitive Assessment (MoCA), Test of Variables of Attention (TOVA), and subtests from the Cogstate battery. HIV+ subjects were divided into groups based on their CAT results at their final visit (bottom 20%, top 20%, middle 60%). Primary analyses focused on the comparison between HIV+ individuals that performed worse on CATs (bottom 20%) and the overall HIV+ group (middle 60%). Data were analyzed using linear mixed-effect models with time as the main fixed effect.
The group with the worst (bottom 20%) CAT performance showed a difference in trajectory for MoCA (p=.003), TOVA (p ≤.048), and Cogstate (p≤.046) over the course of the study period compared to the overall HIV+ group. A battery of three central auditory tests showed a significant difference in cognitive trajectory over a relatively short study period of 3.5 years independent of age (bottom 20% vs. HIV+, p<0.05).
Results were consistent with CATs tracking cognitive function over time, suggesting that central auditory processing can provide a window into CNS performance. CATs can be simple to perform and are relatively insensitive to education and socioeconomic status because they only require repeating sentences, numbers, or detecting gaps in noise. These tests could potentially provide a time-efficient, low-cost way to screen for and monitor cognitive decline in patients with HIV making them a useful surveillance tool for this major public health problem.