Structural connectome differences in HIV infection: brain network segregation associated with nadir CD4 cell count

Area of Science:

• Neuroscience
• Medical Imaging
• Infectious Diseases

Background:

• HIV infection can impact the central nervous system.
• Combination antiretroviral therapy (cART) improves HIV management but neurological complications persist.
• Understanding structural brain changes in HIV is crucial for predicting and mitigating neurological deficits.

Purpose of the Study:

• To investigate differences in structural brain network organization between HIV-positive and HIV-negative individuals using diffusion tensor imaging (DTI).
• To explore the association between HIV infection and brain network metrics derived from fractional anisotropy (FA) and mean diffusivity (MD).
• To correlate brain network metrics with nadir CD4 cell count and cognitive performance in individuals with HIV.

Main Methods:

• Diffusion Tensor Imaging (DTI) was used to acquire structural brain data.
• Global and nodal graph theory metrics were applied to analyze brain network organization based on FA and MD.
• Neuropsychological testing was administered to assess cognitive function.

Main Results:

• HIV-positive individuals showed a lower FA global clustering coefficient compared to HIV-negative individuals, indicating altered network segregation.
• HIV-positive individuals exhibited reduced MD nodal degree in the left thalamus, suggesting changes in thalamic centrality.
• Within the HIV-positive group, FA global clustering coefficient correlated positively with nadir CD4 cell count.
• Cognitive performance was associated with FA-based network metrics: negatively with characteristic path length and positively with global efficiency.

Conclusions:

• HIV infection is associated with altered structural brain network segregation and thalamic centrality, even with cART.
• Low nadir CD4 cell count may be a risk factor for these neurological alterations.
• Graph theory metrics derived from DTI show promise as neural biomarkers for identifying individuals at risk of HIV-related neurological complications.