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HIV brain impairment: who gets it, and why?
Gus Cairns, 2012-03-12 10:50:00
A number of papers at the 19th Conference on Retroviruses and Opportunistic Infections presented advances in research on HIV-related brain impairment and neurocognitive problems.
A couple of problems have dogged research into HIV-related brain impairment. One is how to differentiate between degrees of severity. Psychological tests can detect barely noticeable slowing of performance but the high prevalence of this asymptomatic neurocognitive impairment (ANI) overestimates the proportion of people with HIV who have real difficulty with working or daily life. We also do not know to what extent ANI is a predictor of the development of significant impairment, because some people improve, especially with antiretroviral treatment (ART).
The other problem is how to link neurological findings uncovered by brain scanning with the results of psychological tests: some studies, while uncovering both changes in cognitive performance and evidence of inflammation in the brain in HIV-positive people, have found little statistical linkage between the two.
The cause of brain impairment also remains uncertain: it is thought to be to do with HIV-induced inflammation of the microglia, the cells that function as the brain’s immune system, but exact causes remain elusive and recent studies have found that diabetes and fat accumulation are risk factors too. Finally, it remains unknown to what extent HIV-positive people on ART will still be more likely than HIV-negative people to develop dementia.
ANI is very common: in the largest ongoing study of HIV and neurocognitive problems, CHARTER, 52% of patients were found to have some degree of brain impairment, but the majority was asymptomatic.
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