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Structural and functional brain abnormalities in HIV disease revealed by multimodal MRI fusion: association with cognitive function
  Clinical Infectious Diseases, 18 September 2020
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By applying an innovative analytic approach that "fuses" multimodal MRI data, we identified co-alterations in brain structure and function that correlated with cognitive function. Specifically, global T score was linked to reduced volume in the thalamus and visual, posterior parietal, and orbitofrontal cortices, reduced white matter integrity throughout the corpus callosum and association fibers, and altered activity in frontal-parietal and occipital networks.
PWH had lower component scores for both FA and GMV, suggesting that HIV-associated alterations in brain structure drive neurocognitive impairment. A unique feature of multimodal fusion is its ability to discover linked alterations in spatially distinct brain regions, even when there is no direct morphologic connection. Building upon a literature dominated by unimodal analyses, our results support the role of diffuse co-alterations in brain structure and function in neuroHIV [5-7].

HIV-associated neurocognitive impairment remains a prevalent comorbidity that impacts daily functioning and increases morbidity. While HIV infection is known to cause widespread disruptions in the brain, different MRI modalities have not been effectively integrated. This study applied 3-way supervised fusion to investigate how structural and functional co-alterations affect cognitive function.
Participants (59 with HIV and 58 without HIV) completed comprehensive neuropsychological testing and multimodal MRI scanning to acquire high-resolution anatomical, diffusion-weighted, and resting-state functional images. Pre-processed data was reduced using voxel-based morphometry, probabilistic tractography, and regional homogeneity, respectively. We applied multimodal canonical correlation analysis with reference plus joint independent component analysis (MCCAR+jICA), using global cognitive functioning as the reference.
Compared to controls, participants with HIV had lower global cognitive functioning. One joint component was both group discriminating and correlated with cognitive function. This component included the following covarying regions: fractional anisotropy in the corpus callosum, short and long association fiber tracts, and corticopontine fibers; gray matter volume in thalamus, prefrontal cortex, precuneus, posterior parietal regions, and occipital lobe; and functional connectivity in fronto-parietal and visual processing regions. Component loadings for fractional anisotropy also correlated with immunosuppression.
These results suggest that co-alterations in brain structure and function can distinguish people with and without HIV and may drive cognitive impairment. As MRI becomes more commonplace in HIV care, multimodal fusion may provide neural biomarkers to support diagnosis and treatment of cognitive impairment

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