Accelerated brain aging among HIV-infected adults might be caused in part by altered deep sleep patterns, new research suggests.
Using a measure known as the brain age index (BAI) – a machine-learning model that measures deviations in brain activity during sleep relative to healthy individuals – investigators identified 34 sleep electroencephalogram features that were significantly altered by HIV infection. The most notable of these was the decline in slow-wave activity during non-REM sleep, which has been previously associated with MRI markers of brain aging in healthy adults.
“One of the functions of slow-wave sleep appears to be its association with the glymphatic system, which clears [metabolic] waste products and supports memory consolidation,” study coauthor Brandon Westover, MD, PhD, associate professor of neurology at Massachusetts General Hospital/Harvard Medical School, Boston, said in an interview. “It’s also believed to be associated with an accelerated risk for dementia and other cognitive issues.”
Previous work conducted at Johns Hopkins and other institutions confirm Dr. Westerson’s hypothesis. Charlene Gamaldo, MD, medical director of Johns Hopkins Sleep Disorders Center in Baltimore, pointed to other study findings in patients with neurodegenerative disease that have shown a link between predominant habitual sleep positions and dementia, potentially driven by inefficient glymphatic transport. Dr. Gamaldo was not involved in the current study.
Threefold acceleration vs. healthy volunteers
“We’ve been grappling with whether people with HIV on ART experience accelerated aging or accentuated aging,” coauthor Shibani Mukerji, MD, PhD, associate director of the neuroinfectious diseases unit at Massachusetts General, said in an interview. “We have yet to have biomarkers to address this question, and most of the tools are limited to invasive or expensive diagnostics. “In general, sleep and its influence on health have been understudied in the HIV population.”
To address this question, the researchers retrospectively examined a Massachusetts General Hospital database of diagnostic sleep study participants from 2008 to 2018, identifying 3,155 healthy, HIV-negative control subjects and 43 HIV-positive participants. Thirty-four (79%) of the HIV-positive participants were men, 30 (70%) were White, and 38 (93%) were virally suppressed at the time of their sleep study. Four patients were taking efavirenz, 13 were taking an integrase strand transfer inhibitor, and all were adherent to antiretroviral therapy (ART) at the time of their sleep study.
None of the HIV-positive participants had a history of secondary brain infection or brain tumor, although one patient had recovered fully from a previous HIV-associated encephalitis.
The study findings, which were published online March 30, 2021, in Sleep, first showed that HIV-positive participants had an average BAI of 3.19 years (standard error of the mean,1.43 years), compared with the control participants, who had an average BAI of –0.16 (SEM, 0.18 years).
These findings held after adjustment for potential confounders (age, sex, race, tobacco use disorder, and alcohol use disorder), yielding a total effect of HIV on BAI of 3.35 years (P < .01).
“Despite being well controlled on ART, HIV-positive individuals who had participated in the sleep studies still had elevated brain age,” said Dr. Westover. “We didn’t have enough information to determine the pathways by which HIV increases the BAI, but chronic inflammation appears to be an important factor.”
The findings also demonstrated that comorbidities accounted for roughly a quarter of the effect of HIV on BAI. However, the lack of statistical significance (in part because of the limited sample size) precluded the ability to determine if treating or preventing them might influence the degree to which HIV affects BAI and, in turn, cognitive decline.