Abstract
Background
As people with HIV (PWH) age, it remains unclear whether they are at higher risk for age-related neurodegenerative disorders, e.g., Alzheimer disease (AD), and if so, how to differentiate HIV-associated neurocognitive impairment from AD. We examined a clinically-available blood biomarker test for AD (plasma Aβ42/Aβ40 ratio), in cognitively-normal (CN) or cognitively-impaired (CI) PWH and people without HIV (PWoH) who were CN or with symptomatic AD.
Methods
66 PWH (age >40 years) (HIV RNA <50 copies/mL) and 195 PWoH provided blood samples, magnetic resonance imaging (MRI), and completed a neuropsychological battery or Clinical Dementia Rating scale (CDR). Participants were categorized by impairment (PWH_CN
n = 43; PWH_CI
n = 23; PWoH_CN
n = 138; PWoH_AD
n = 57). Plasma Aβ42 and Aβ40 concentrations were obtained using a liquid chromatography-tandem mass spectrometry method to calculate the PrecivityAD® Amyloid Probability Score (APS). The APS incorporates age and apolipoprotein E proteotype into a risk score for brain amyloidosis. Plasma Aβ42/Aβ40 and APS were compared between groups and assessed for relationships with hippocampal volumes or cognition and HIV clinical characteristics (PWH only).
Results
The plasma Aβ42/Aβ40 ratio was significantly lower, and APS higher, in PWoH_AD compared to other groups. A lower Aβ42/Aβ40 ratio and higher APS was associated with smaller hippocampal volumes for PWoH_AD. The Aβ42/Aβ40 ratio and APS were not associated with cognition or HIV clinical measures for PWH.
Conclusions
The plasma Aβ42/Aβ40 ratio can serve as a screening tool for AD and may help differentiate effects of HIV from AD within PWH, but larger studies with older PWH are needed.
