HIV Infection and Aging Independently Affect Brain Function as Measured by Functional Magnetic Resonance Imaging

Abstract

We investigated interactions between HIV and aging on brain function demands using functional magnetic resonance imaging (fMRI). A multiple regression model studied the association and interaction between fMRI measures, HIV serostatus, and age for 26 HIV infected (HIV+) and 25 seronegative (HIV−) subjects. While HIV serostatus and age independently affected fMRI measures, no interaction occurred. Functional brain demands in HIV+ subjects were equivalent to ~15–20 year older HIV− subjects. Frailty parallels between HIV and aging could result from continued immunological challenges depleting resources and triggering increased metabolic demands. fMRI could be a non-invasive biomarker to assess HIV in the brain.

Abnormal MEG Oscillatory Activity during Visual Processing in the Prefrontal Cortices and Frontal Eye-Fields of the Aging HIV Brain

“…In contrast to several recent reports, we did not observe hypo-activation in the primary visual regions of HIV-infected patients [17], [18]. Previous studies have shown decreased regional cerebral blood flow (CBF) in the primary visual cortices during rest, and reduced fMRI BOLD activation in occipital cortices during visual stimulation.…”

“…The current study did observe greater activation (marginal means) in the left occipital region in uninfected controls, but this effect did not approach significance. This difference between studies may reflect the substantially larger sample size used by Ances et al, as these studies had more than twice as many participants per group than the current study and thereby, greater sensitivity to detect smaller effects [17], [18]. However, Ances and colleagues also recently showed that the test-retest reliability of fMRI (BOLD and CBF) measures in HIV-infected patients are much lower than controls, and that the intrinsic coupling between oxygenation and blood flow is aberrant in HIV-infected patients [19].…”

“…Such a breakdown in the coupling of these parameters could produce spurious results and lead to inconsistent findings between fMRI and MEG studies. Unfortunately, these studies only investigated the occipital area alone [17], [19] or the lenticular nuclei and the occipital region [18]. Thus, it is impossible to discern whether these previous fMRI studies would have also detected the larger group effects that we observed in the right DLPFC, right FEF, and posterior cingulate.…”

“…Interestingly, outside of the association cortices, the opposite pattern (HIV<controls) may exist in the primary sensory cortices. Two recent studies showed decreased activation in the primary visual cortices during a basic visual stimulation task using fMRI, and reduced resting cerebral-blood-flow to the same visual regions in HIV-infected patients with and without cognitive deficits relative to uninfected controls [17], [18]. These two studies did not evaluate cortical areas outside of the occipital region, which complicates any direct comparison to earlier studies of working memory and attention.…”

Neuropsychological profiles of adults and older adults with HIV

“…3 individuals 15-20 years older (Ances et al, 2010). In an adult and older adult HIV+ cohort, Fazeli et al (2014) elucidated both the presence of subtle cognitive impairment in 47% of the study sample and the persistence of a mild and diffuse pattern of cognitive impairment in the era of HAART.…”