Abstract
BackgroundHIV is a neurotropic virus, and it can bring about neurodegeneration and may even result in cognitive impairments. The precise mechanism of HIV-associated white matter (WM) injury is unknown. The effects of multiple clinical contributors on WM impairments and the relationship between the WM alterations and cognitive performance merit further investigation.MethodsDiffusion tensor imaging (DTI) was performed in 20 antiretroviral-naïve HIV-positive asymptomatic neurocognitive impairment (ANI) adults and 20 healthy volunteers. Whole-brain analysis of DTI metrics between groups was conducted by employing tract-based spatial statistics (TBSS), including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD). DTI parameters were correlated with clinical variables (age, CD4+ cell count, CD4+/CD8+ ratio, plasma viral load and duration of HIV infection) and multiple cognitive tests by using multilinear regression analyses.ResultsDTI quantified diffusion alterations in the corpus callosum and corona radiata (MD increased significantly, P < 0.05) and chronic axonal injury in the corpus callosum, corona radiata, internal capsule, external capsule, posterior thalamic radiation, sagittal stratum, and superior longitudinal fasciculus (AD increased significantly, P < 0.05). The impairments in the corona radiata had significant correlations with the current CD4+/CD8+ ratios. Increased MD or AD values in multiple white matter structures showed significant associations with many cognitive domain tests.ConclusionsWM impairments are present in neurologically asymptomatic HIV+ adults, periventricular WM (corpus callosum and corona radiata) are preferential occult injuries, which is associated with axonal chronic damage rather than demyelination. Axonopathy may exist before myelin injury. DTI-TBSS is helpful to explore the WM microstructure abnormalities and provide a new perspective for the investigation of the pathomechanism of HIV-associated WM injury.
Highlights
HIV is a neurotropic virus, and it can bring about neurodegeneration and may even result in cognitive impairments
HIV-associated neurocognitive disorders (HAND) can be clinically subdivided into three categories: asymptomatic neurocognitive impairment (ANI), mild neurocognitive disorder (MND) and HIV-associated dementia (HAD) [3]
The anterior limb of internal capsule, external capsule, retrolenticular part of the internal capsule, posterior corona radiata, posterior thalamic radiation, sagittal stratum, and superior longitudinal fasciculus presented significantly increased axial diffusivity (AD), and we found that most of them were close to the ventricles
Summary
HIV is a neurotropic virus, and it can bring about neurodegeneration and may even result in cognitive impairments. ANI is the mildest and most common type of HAND (accounting for 70%), which is characterized by mild cognitive impairment on neuropsychological performance tests without obvious accompanying difficulties in daily functioning [4]. These definitions are mainly based upon an individual’s performance on multiple cognitive domains and a brief self-report of cognitive difficulties in daily life. These neuropsychological tests are time consuming (~ 3 h) and are usually performed in specific research institutions [3], so patients in ANI stages are rarely diagnosed in traditional outpatient visits (15–30 min)
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