Plasma Aβ42/Aβ40 ratios–a biomarker for Alzheimer disease (AD)–could be used to distinguish HIV-associated cognitive impairment from AD in aging people living with HIV (PLWH), a small study suggested.
About This Study
“Plasma Aβ42/Aβ40 ratios are not reduced in older people living with HIV” was published online on Jan. 5, 2023, in Clinical Infectious Diseases. The lead author is Sarah A. Cooley, Ph.D., of Washington University School of Medicine. (Disclosure note: Three authors are employees of C2N Diagnostics, which makes the test for determining plasma Aβ42/Aβ40 ratios.)
Key Research Findings
Blood samples from 66 virally-suppressed PLWH and 195 HIV-negative people–all > 40 years old–were analyzed for plasma Aβ42/Aβ40 ratios. Participants also underwent magnetic resonance imaging to determine hippocampal volumes and had their neurocognitive performance tested.
Among PLWH, 43 participants were considered to have no cognitive impairment, while 23 participants were cognitively impaired, albeit relatively mildly. Aβ42/Aβ40 ratios were similar between both groups and were not associated with HIV clinical characteristics, such as CD4 count. Patterns of cognitive decline among the 23 PLWH considered impaired corresponded to those seen in HIV-related neurocognitive impairment and did not match patterns seen in AD.
Among HIV-negative controls, 138 participants were not cognitively impaired, and 57 participants had AD. Aβ42/Aβ40 ratios were significantly lower in the AD group than in the three other groups. Among the AD group, lower ratios were associated with smaller hippocampal volumes.
There were significant demographic differences between the groups. The AD group was much older than the other groups and consisted mostly of white people: 7% in the AD group were African American compared to 43% of cognitively unimpaired HIV-negative participants, 63% of cognitively unimpaired PLWH, and 70% of cognitively impaired PLWH. The HIV-negative cohort included significantly more women than the PLWH cohort.
The study authors noted that cognitive impairment was also assessed differently: PLWH completed a set of neuropsychological tests, while HIV-negative participants were assessed individually by clinicians based on the clinical dementia rating scale.
Discussion Highlights and Implications for Practice
The Aβ42/Aβ40 ratio differences between cognitively impaired PLWH and HIV-negative people with AD suggest that this biomarker could be used to distinguish between cognitive problems related to HIV and those indicative of AD, study authors suggested. They called for further studies that include older PLWH and follow participants for longer periods of time.
By Barbara Jungwirth
Source : TheBodyPro