University of Missouri - Saint Louis

The Graduate School


An oral examination in defense of the dissertation for the degree

Doctor of Philosophy in Psychology

Jodi M. Heaps
M.A. in Psychology, December 2010, University of Missouri-St .Louis
B.A. in Psychology, May 2006, University of Missouri-St. Louis

Diffusion tensor imaging in human immunodeficiency virus and co-morbid Hepatitis C virus



Previous studies have demonstrated that HIV/HCV co-infection is associated with impaired cognitive function though 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. 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 on the index of liver function. 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 (mono p=0.007; co- infected p=0.001) compared to controls with both groups having lower FA values. Additionally, the HIV/HCV+ group had higher RD (p=0.019) compared to controls in the corpus callosum, particularly in the anterior sections. Increased RD in the corpus callosum predicted performance on executive function/working memory measures at a trend level (p=0.078) 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.


Date: November 12, 2012

Time: 11:00 a.m. to 1:00 p.m.

Place:432 Stadler Hall


Defense of Dissertation Committee


Robert Paul, Ph.D. (Advisor)

Beau Ances, M.D. Ph.D


Michael Griffin, Ph.D.

George Taylor, Ph.D.