A diffusion tensor imaging and neurocognitive study of HIV-positive children who are HAART-naïve “slow progressors”

Abstract

There are few neuropsychological or neuroimaging studies of HIV-positive children with "slow progression". "Slow progressors" are typically defined as children or adolescents who were vertically infected with HIV, but who received no or minimal antiretroviral therapy. We compared 12 asymptomatic HIV-positive children (8 to 12 years) with matched controls on a neuropsychological battery as well as diffusion tensor imaging in a masked region of interest analysis focusing on the corpus callosum, internal capsule and superior longitudinal fasciculus. The "slow progressor" group performed significantly worse than controls on the Wechsler Abbreviated Scale of Intelligence Verbal and Performance IQ scales, and on standardised tests of visuospatial processing, visual memory and executive functioning. "Slow progressors" had lower fractional anisotropy (FA), higher mean diffusivity (MD) and radial diffusivity (RD) in the corpus callosum (p= <0.05), and increased MD in the superior longitudinal fasciculus, compared to controls. A correlation was found between poor performance on a test of executive function and a test of attention with corpus callosum FA, and a test of executive function with lowered FA in the superior longitudinal fasiculus. These data suggest that demyelination as reflected by the increase in RD may be a prominent disease process in paediatric HIV infection.

White Matter Development is Potentially Influenced in Adolescents with Vertically Transmitted HIV Infections: A Tract-Based Spatial Statistics Study

“…Xuan et al 29 reported that the mean FA values were significantly lower and the mean AIDS dementia complex values were significantly higher in the corpus callosum and periventricular, frontal, and parietal WM in the asymptomatic group. A similar result has been found in the study by Hoare et al 14 These results imply that patients with HIV may have alterations in the diffusion of water molecules in their brain WM, whether they have symptoms or not. In our study, most of the subjects were also asymptomatic, and there were no significant differences in the Montreal Cognitive Assessment and Mini-Mental State Examination scores between the 2 groups.…”

“…For example, a voxel-based morphometry study reported WM atrophy in the posterior part of corpus callosum, external capsule, and ventral temporal lobe in vertically infected youths (age range, 13-25 years). 13 Hoare et al 14 found that vertically HIV-infected children (age range, 8 -12 years) had lower FA and higher MD and radial diffusivity (RD) in the corpus callosum and increased MD in the superior longitudinal fasciculus. Taken together, these findings suggest that abnormal WM integrity may also be present in adolescents (age range, 12-18 years) with vertically transmitted HIV infections.…”

Clinical associations of white matter damage in cART-treated HIV-positive children in South Africa

“…A previous DTI study of HIV-positive children, who were slow progressors, found increases in RD that were more significant than the decreases in AD (Hoare et al 2012). The results suggested that the alteration in these two diffusivities is different, that demyelination as reflected by the increase in RD may be the prominent disease process associated with HIV infection in HIV, and axonal injury may occur at a weaker level in slow progressors (Hoare et al 2012).…”

“…The results suggested that the alteration in these two diffusivities is different, that demyelination as reflected by the increase in RD may be the prominent disease process associated with HIV infection in HIV, and axonal injury may occur at a weaker level in slow progressors (Hoare et al 2012). However, in this study of cART-treated children, we found both decreased AD and increased RD in a number of the white matter regions reported, indicating that both axonal injury and myelin loss (Song et al 2002) may be involved in this group of children.…”

“…DTI can be regarded as particularly suitable for use with this sample of children because it is a non-invasive technique that allows for rapid data collection (Hoare et al 2012). DTI is able to examine the microstructural integrity and directionality of the white matter, and therefore capable of providing information on the location of white matter microstructural changes correlated with clinical variables in vertically infected HIVpositive children.…”