Brain HIV burden and length of survival after AIDS diagnosis.

Patients with AIDS in the late stages of disease can develop dementia. Previous studies have suggested HIV encephalitis is the pathological substrate of HIV-associated dementia. We hypothesized that patients who survive longer after the initial diagnosis of AIDS would have a higher brain HIV burden and consequently manifest dementia. We examined the relationship between length of survival after AIDS diagnosis and the presence of HIV encephalitis or HIV-associated dementia. We studied retrospectively the following parameters in 74 consecutive AIDS autopsies: length of survival after AIDS diagnosis, clinical diagnosis of dementia, and neuropathologic findings (including HIV burden assessment). Multinucleated giant cells (MNGC) were identified in 20% of the brains studied. HIV gp41 was detected by immunocytochemistry in 54%, approximately half of which had abundant HIV burden. Brains from all 4 patients who were clinically diagnosed with dementia and had no opportunistic neuropathologic changes contained MNGC and abundant HIV burden. Survival after AIDS diagnosis was significantly longer in patients with MNGC (p = 0.03) or abundant HIV burden (p = 0.02). A trend toward longer survival after AIDS diagnosis was apparent in patients with dementia, but did not reach statistical significance. These findings suggest that prolonged survival with immunosuppression may be a prerequisite for the development of HIV encephalitis.