Many people with HIV on antiretroviral therapy (ART) have viral genetic material in the cells of their cerebrospinal fluid (CSF), and these individuals are more likely to experience memory and concentration problems, according to new data published online today in the Journal of Clinical Investigation.

A study of 69 individuals on long-term ART found that nearly half of the participants had persistent HIV in cells in their CSF, and 30% of this subset experienced neurocognitive difficulties. These findings suggest that HIV can persist in the nervous system even when the virus is suppressed in a patient’s blood with medication. The study was funded by the National Institute of Allergy and Infectious Diseases (NIAID) and the National Institute of Mental Health (NIMH), both parts of the National Institutes of Health (NIH).

Investigators from the University of North Carolina, the University of Pittsburgh, and Yale University studied participants enrolled in the AIDS Clinical Trials Group (ACTG) HIV Reservoirs Cohort Study. This primarily male group—aged 45 to 56—of long-term HIV survivors had infections controlled with ART for, on average, 9 years. Researchers analyzed each participant’s CSF for HIV DNA and then compared these data to each participants’ results from standard neurocognitive evaluations. About half of participants had viral DNA in cells in the CSF, indicating the presence of latent virus, even though standard HIV RNA "viral load" tests of the cell-free CSF fluid were positive in only 4% of participants. Investigators also found that 30% of individuals with persistent HIV DNA in the CSF experienced clinical neurocognitive impairment compared with 11% of individuals whose CSF did not contain viral DNA.

Many researchers hypothesize that HIV-related inflammation causes HIV-associated neurocognitive disorder (HAND). The new findings suggest that the presence of persistent HIV-infected cells in the central nervous system (CNS), despite long-term ART, may play a role in neurocognitive impairment. The authors note that the overall frequency of neurocognitive impairment in this group was relatively low and that the association does not confirm that HIV DNA causes HAND. Overall, the current study found that examining CSF cells revealed a higher-than-expected prevalence of persistent HIV in the CNS, which may be a significant obstacle to efforts to eradicate HIV from the body.