Lower cerebrovascular reactivity in HIV-associated cognitive impairment: compared with normal aging and vascular cognitive impairment

Abstract Objectives Older people living with HIV (PWH) have a higher risk for HIV-associated cognitive impairment, which may be exacerbated by age-related cerebrovascular disorders. However, the pathophysiology underlying the cognitive impairment in PWH remains unclear. The goal of this study is to evaluate cerebrovascular dysfunction in PWH and investigate its relationship with cognition. Methods This cross-sectional study included 83 eligible subjects (ages 50–81 years) who completed MRI scans. Cerebrovascular reactivity (CVR) was assessed using blood-oxygenation-level-dependent functional MRI (BOLD-fMRI) during a 5 % carbon dioxide inhalation (hypercapnia challenge). A global cognitive measure of Montreal Cognitive Assessment (MoCA) and a battery of neuropsychological tests were also performed to assess their cognitive status. Results Quality-assured CVR scans were obtained from 63 subjects (22 PWH, 41 non-HIV controls), who were divided into 4 groups: 11 PWH without symptomatic cognitive impairment (PWH-sCI–), 11 PWH with symptomatic cognitive impairment (PWH-sCI+), 23 non-HIV controls with normal cognition (non-HIV-NC), and 18 non-HIV controls with cognitive impairment (non-HIV-CI). HIV status was associated with relatively lower regional gray matter CVR in the frontal lobe (p=0.001), parietal lobe (p=0.003), and basal ganglia (p=0.001), indicating cerebrovascular dysfunction in these brain regions in PWH compared to the non-HIV controls. Lower whole-brain and regional gray matter CVR were significantly associated with worse global cognition measured by MoCA in older PWH (p<0.037). Conclusions Our findings provided direct evidence that cerebrovascular dysfunction is associated with cognitive impairment in aging PWH, suggesting CVR is a promising candidate imaging biomarker of cerebrovascular dysfunction associated with cognitive impairment in PWH.