Imaging of Brain Structural and Functional Effects in People With Human Immunodeficiency Virus

Abstract

Before the introduction of antiretroviral therapy, human immunodeficiency virus (HIV) infection was often accompanied by central nervous system (CNS) opportunistic infections and HIV encephalopathy marked by profound structural and functional alterations detectable with neuroimaging. Treatment with antiretroviral therapy nearly eliminated CNS opportunistic infections, while neuropsychiatric impairment and peripheral nerve and organ damage have persisted among virally suppressed people with HIV (PWH), suggesting ongoing brain injury. Neuroimaging research must use methods sensitive for detecting subtle HIV-associated brain structural and functional abnormalities, while allowing for adjustments for potential confounders, such as age, sex, substance use, hepatitis C coinfection, cardiovascular risk, and others. Here, we review existing and emerging neuroimaging tools that demonstrated promise in detecting markers of HIV-associated brain pathology and explore strategies to study the impact of potential confounding factors on these brain measures. We emphasize neuroimaging approaches that may be used in parallel to gather complementary information, allowing efficient detection and interpretation of altered brain structure and function associated with suboptimal clinical outcomes among virally suppressed PWH. We examine the advantages of each imaging modality and systematic approaches in study design and analysis. We also consider advantages of combining experimental and statistical control techniques to improve sensitivity and specificity of biotype identification and explore the costs and benefits of aggregating data from multiple studies to achieve larger sample sizes, enabling use of emerging methods for combining and analyzing large, multifaceted data sets. Many of the topics addressed in this article were discussed at the National Institute of Mental Health meeting "Biotypes of CNS Complications in People Living with HIV," held in October 2021, and are part of ongoing research initiatives to define the role of neuroimaging in emerging alternative approaches to identifying biotypes of CNS complications in PWH. An outcome of these considerations may be the development of a common neuroimaging protocol available for researchers to use in future studies examining neurological changes in the brains of PWH.

Keywords: MEG; MRI; PET; harmonization; neuroimaging; structure.

Figure 1.

A novel machine learning approach identified a human immunodeficiency virus (HIV) diagnostically specific pattern of cortical and subcortical volume, surface area, mean curvature, or thickness deficits in the regions, noted in green. The top 4 sagittal images mark the precentral motor strip, superior parietal cortex, pars triangularis, insula, inferior and middle temporal gyri, and superior frontal cortex. The bottom 4 sagittal images mark the caudal anterior cingulum, parahippocampal gyrus, occipital cortex, pericalcarine, fusiform, temporal pole, precunneus, and medial frontal cortex. The leftward-facing sagittal image marks the thalamus, hippocampus, and accumbens. The pattern of cortical and subcortical regions specific to HIV emerged from a novel machine learning approach that differentiated HIV from other diagnoses (alcohol use disorder, HIV plus alcohol use disorder, and controls. (This image is a portion of figure published elsewhere [, p 4], reprinted with permission from Elsevier.)