Topological Organization of Whole-Brain White Matter in HIV Infection

Abstract

Infection with human immunodeficiency virus (HIV) is associated with neuroimaging alterations. However, little is known about the topological organization of whole-brain networks and the corresponding association with cognition. As such, we examined structural whole-brain white matter connectivity patterns and cognitive performance in 29 HIV+ young adults (mean age = 25.9) with limited or no HIV treatment history. HIV+ participants and demographically similar HIV- controls (n = 16) residing in South Africa underwent magnetic resonance imaging (MRI) and neuropsychological testing. Structural network models were constructed using diffusion MRI-based multifiber tractography and T₁-weighted MRI-based regional gray matter segmentation. Global network measures included whole-brain structural integration, connection strength, and structural segregation. Cognition was measured using a neuropsychological global deficit score (GDS) as well as individual cognitive domains. Results revealed that HIV+ participants exhibited significant disruptions to whole-brain networks, characterized by weaker structural integration (characteristic path length and efficiency), connection strength, and structural segregation (clustering coefficient) than HIV- controls (p < 0.05). GDSs and performance on learning/recall tasks were negatively correlated with the clustering coefficient (p < 0.05) in HIV+ participants. Results from this study indicate disruption to brain network integrity in treatment-limited HIV+ young adults with corresponding abnormalities in cognitive performance.

Keywords: HIV; cognition; network analysis; whole-brain connectivity.

FIG. 1.

Structural network analysis visualizations. Left: A visualization of imaging-based reconstructions of anatomy, showing diffusion magnetic resonance imaging (MRI)-based tractography and T1-weighted MRI-based gray matter segmentations. The left hemisphere shows Desikan–Killiany regions-of-interest and the right hemisphere shows streamline tractography curves used to define connectivity between regions. Right: A visualization of a structural network model derived from neuroimaging data. The left hemisphere shows Desikan–Killiany regions-of-interest and the right hemisphere shows a node-link diagram representing the topological organization of white matter. Nodes are placed at the centroid of each region and the links are derived from the average fiber bundle length between the pairs of regions with structural connections. Color images available online at www.liebertpub.com/brain