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CROI 2010: HIV/HCV Coinfected Patients Demonstrate Poorer Neurocognitive Performance, but No Difference in Neural Imaging

HIV/HCV coinfected individuals with good HIV suppression on performed more poorly than HIV monoinfected people on neurocognitive tests, but the 2 groups showed no significant differences in neural imaging measures, according to a study presented at the recent 17th Conference on Retroviruses and Opportunistic Infections in San Francisco (CROI 2010).

H. Peng from Washington University in St. Louis and colleagues compared performance on "neuropsychometric" tests and differences in brain imaging measurements in HIV positive and HIV/HCV coinfected individuals.

Neural imaging can help assess anatomical changes and physiological activity in difference parts of the brain. Since HIV and hepatitis C virus (HCV) have both been shown to affect neurocognitive function, the researchers hypothesized that HIV/HCV coinfected people would have greater neurocognitive impairment and more abnormalities in brain white matter, which consists largely of axons connecting neurons.

The study included 15 HIV monoinfected and 13 HIV/HCV coinfected patients on ART. The 2 groups had a similar sex distribution and education levels, but the coinfected participants were older on average.

Participants' neurocognitive performance was assessed using 2 common tests, trail-making parts A & B and the digit symbol test. Raw scores were standardized into z scores, and the researchers calculated a composite neuropsychological score (NPZ3) from the average of standardized values.

The neuronal imaging component of the study employed diffusion tensor imaging, a magnetic resonance imaging technique that shows how water diffuses in the brain; this method is particularly useful for analyzing white matter. Diffusion tensor images were mapped onto a common whole brain "skeleton" so the researchers could compare specific regions of interest, including the corpus callosum (the structure that connects the left and right hemispheres).

Results

• HIV/HCV coinfected participants demonstrated more impairment than HIV monoinfected individuals on each of the neuropsychological tests.
• The coinfected group had significantly worse scores on the trail-making part B (P = 0.01) and digit symbol test (P =0.04).
• Diffusion tensor imaging values for mean diffusivity (P = 0.15) and axial diffusivity (P = 0.07) were lower for HIV/HCV coinfected compared with HIV monoinfected participants.
• However, there were no significant differences in neuroimaging measures for brain regions of interest.
• No correlations were observed between CD4 cell count or HIV viral load and either NPZ3 scores or diffusion tensor imaging measures.
• Based in these findings, the investigators concluded, "The combination of HIV/HCV coinfection affected brief neurocognitive screening, but not neuroimaging measures."

"Neither neuropsychological nor neuroimaging measures correlated with existing HIV serum markers," they continued. "This lack of association may reflect relatively good virologic control by ART. Clinically significant neurocognitive dysfunction but not neuroimaging abnormalities are exacerbated by HCV infection in the setting of optimally treated HIV infection."

Washington Univ, St Louis, MO; Univ of Missouri-St Louis, MO.

4/6/10

Reference

H Peng, J Thomas, N Parker, and others. HCV/HIV Co-infection Affects Neurocognitive Measures, but Does Not Affect Neuroimaging Measures. 17th Conference on Retroviruses & Opportunistic Infections (CROI 2010). San Francisco. February 16-19, 2010. Abstract 402.