The prevalence and incidence of neurocognitive impairment in the HAART era.

OBJECTIVES: HAART suppresses HIV viral replication and restores immune function. The effects of HAART on neurological disease are less well understood. The aim of this study was to assess the prevalence and incidence of neurocognitive impairment in individuals who initiated HAART as part of an AIDS clinical trial.
DESIGN: A prospective cohort study of HIV-positive patients enrolled in randomized antiretroviral trials, the AIDS Clinical Trials Group (ACTG) Longitudinal Linked Randomized Trials (ALLRT) study.
METHODS: We examined the association between baseline and demographic characteristics and neurocognitive impairment among 1160 subjects enrolled in the ALLRT study.
RESULTS: A history of immunosuppression (nadir CD4 cell count < 200 cells/microl) was associated with an increase in prevalent neurocognitive impairment. There were no significant virological and immunological predictors of incident neurocognitive impairment. Current immune status (low CD4 cell count) was associated with sustained prevalent impairment.
CONCLUSION: The association of previous advanced immunosuppression with prevalent and sustained impairment suggests that there is a non-reversible component of neural injury that tracks with a history of disease progression. The association of sustained impairment with worse current immune status (low CD4 cell count) suggests that restoring immunocompetence increases the likelihood of neurocognitive recovery. Finally, the lack of association between incident neurocognitive impairment and virological and immunological indicators implies that neural injury continues in some patients regardless of the success of antiretroviral therapy on these laboratory measures.