HIV-associated alterations in normal-appearing white matter: a voxel-wise diffusion tensor imaging study.

Area of Science:

• Neuroimaging
• Infectious Diseases
• Neurology

Background:

• Conflicting reports exist regarding HIV's impact on white matter integrity.
• Diffusion Tensor Imaging (DTI) is used to measure white matter integrity.

Purpose of the Study:

• To assess HIV-associated regional changes in normal-appearing white matter (NAWM) integrity using high-resolution DTI.
• To resolve conflicting DTI findings in HIV-associated white matter alterations.

Main Methods:

• Compared DTI measures (FA and MD) in 30 HIV-seropositive (SP) and 30 HIV-seronegative (SN) participants.
• Used voxel-by-voxel analysis on NAWM masks derived from T2-weighted images.
• Controlled for age and substance abuse history in group comparisons.

Main Results:

• No significant demographic or cognitive differences between SP and SN groups.
• Whole-brain DTI measures were equivalent; however, regional analyses revealed significant differences.
• HIV-seropositive individuals showed widespread increases in NAWM mean diffusivity (MD), indicating tissue breakdown.
• Fractional anisotropy (FA) showed variable changes (both increases and decreases) in NAWM in the HIV-seropositive group.

Conclusions:

• HIV infection is associated with decreased white matter integrity in NAWM, primarily indicated by increased MD.
• Variable changes in FA suggest complex alterations in axonal integrity and matrix in HIV-associated white matter damage.
• These findings help explain previous conflicting DTI results in HIV research.