Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Psychology

Date of Defense

12-14-2013

Graduate Advisor

Robert Paul, PhD.

Committee

Griffin, Michael

Taylor, George

Ances, Beau

Abstract

Previous studies have demonstrated that infection with both human immune deficiency virus (HIV) and hepatitis C (HCV) is associated with impaired cognitive function. It is unclear whether co-infection is associated with neuroimaging markers of brain dysfunction. The purpose of the present study was to compare HIV+ individuals, HIV/HCV+ individuals, and seronegative controls using diffusion tensor imaging (DTI) to assess the microstructural integrity of white matter tissue. Methods: Twenty-five HIV+ patients, 25 HIV/HCV+ patients, and 25 seronegative controls matched for age were included in the study. All participants completed an MRI session, neuropsychological testing, and an evaluation of clinical variables including liver health. White matter regions of interest (ROI) were determined using a semi-automatic method based on individual anatomy. DTI metrics including mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) were compared across groups using ANOVA. A regression model including DTI metrics, an index of liver function, and self-reported physical and mental health was performed to determine the relationship between those variables and cognitive performance in the co-infected group. Results: The co-infected group was similar to the mono-infected group in terms of HIV clinical variables. None of the participants met criteria for cirrhosis or fibrosis. There were no differences between groups on DTI metrics in the frontal ROI. In the anterior corpus callosum there was a significant difference between the HIV+ groups compared to controls with both patient groups having lower FA values. Additionally, the HIV/HCV+ group had significantly higher RD compared to controls in the corpus callosum, particularly in the anterior sections. Increased RD in the corpus callosum was associated with performance on executive function/working memory measures only at a trend level (p=0.07) in the co-infected group. Conclusions: Co-infection with HIV and HCV may result in significant alterations in white matter structural integrity as measured by DTI, especially in the anterior corpus callosum. The effect of HIV/HCV co-infection was greater than the effect of HIV mono-infection compared to controls in all regions sampled. These results suggest that the combined effects of the viruses in the brain result in compromised white matter microstructural integrity.

OCLC Number

870712348

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Psychology Commons

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