A diffusion tensor imaging study in HIV patients with and without apathy

[摘要] ENGLISH ABSTRACT: HIV/AIDS is a global epidemic that accounts for a large percentage of the mortality in SouthAfrica every year. Since the implementation of anti-retroviral treatment, HIV positiveindividuals have been living longer, and the cognitive impairment associated with the diseaseis becoming increasingly apparent. During the initial systemic infection of HIV, the virusmigrates through the blood-brain barrier and inflicts axonal injury by causing upregulation ofcytokines and neurotoxic proteins. HIV-associated dementia is a neuropsychologicalclassification of cognitive impairment in HIV and a variety of symptoms have been classifiedas a part of the dementia complex. One of these is apathy, which is thought to be a precursorfor dementia in HIV patients. Three groups of individuals have been recruited and scannedusing magnetic resonance imaging (MRI) to examine changes in the brain. These are an HIVnon-apathetic cohort, an HIV apathetic cohort and a healthy control cohort. Diffusion tensorimaging (DTI) is an MRI technique used to quantitatively assess white matter (WM) integrityusing metrics such as fractional anisotropy (FA). Voxel-based analysis, tract-based spatialstatistics (TBSS) and tractography are three established DTI analysis methods that have beenapplied in numerous studies. However, there are certain methodological strengths andlimitations associated with each technique and therefore all three of these techniques wereused to compare WM differences across groups. The frontal-subcortical pathways are knownto be abnormal in apathy, and this has been demonstrated in a number of imaging studies.Most of these studies have examined apathy in the context of neurodegenerative disorderssuch as Alzheimer's disease and Parkinson's. However, to our knowledge this is the first DTIstudy in HIV apathetic patients. With the tractography method, the anterior thalamic radiationand the corpus callosum were reconstructed for each individual to determine whether therewere any global changes in these tracts. No significant changes were found. However, avariety of regions in the WM were significantly abnormal in the HIV cohorts when comparingthe data at a voxel-based level and using TBSS. This included areas such as the genu andsplenium of the corpus callosum, the internal capsule and corona radiata. Changes in frontalWM for the HIV apathy group are an indication of dysfunction in the frontal-striatal circuits,and previous literature has implicated these circuits in the neuropathology of apathy in avariety of central nervous system (CNS) disorders.

[发布机构] Stellenbosch University