While more than half of long-term virally suppressed participants in a small study published in AIDS showed markers of low-grade immune activation in the central nervous system (CNS), such markers were not associated with lower neurocognitive performance and were "likely clinically benign in most cases," according to the study authors.
Researchers studied blood and cerebrospinal fluid (CSF) samples from 20 people living with HIV whose virus had been suppressed for a median of 13.2 years. None of the participants showed neurocognitive impairment at baseline. In follow-up surveys, no participant reported any change in everyday function due to cognitive impairment. That said, 14 of the 20 participants completed a neurocognitive evaluation, and data indicated a slightly lower mean performance relative to what would be expected of similarly aged people.
One of the immune activation markers, CSF neopterin, decreased with antiretroviral therapy, but remained above the normal range in 55% of participants. The other, neurofilament light protein, dropped to within the normal range for participants' ages while on treatment.
While no participant experienced treatment failure, antiretroviral regimens did change as newer medications became available. Use of these newer drugs, as well as earlier treatment initiation, may impact CNS immune activation over time, study authors noted. They called for further studies on this question, as well as on the interplay of aging-related cognitive function and HIV-related immune activation.