HIV-associated cognitive impairment in sub-Saharan Africa--the potential effect of clade diversity

In the US, HIV dementia occurs in 10-15% of HIV-positive individuals with advanced infection. The prevalence of HIV dementia in sub-Saharan countries, where the vast majority of individuals with HIV reside, is largely unknown. This Review will summarize our current understanding of HIV-associated cognitive impairment in resource-limited settings, focusing specifically on the countries of sub-Saharan Africa. We will describe the frequency of HIV dementia and HIV-associated cognitive impairment from several case series in the sub-Saharan region. We will then summarize recent studies from Uganda and Ethiopia that included detailed neuropsychological assessments. The potential influence of clade diversity on HIV-associated cognitive impairment will be discussed. Differences between the results of the studies in Uganda and in Ethiopia raise the possibility that HIV subtypes might have different biological properties with respect to their capacity to cause HIV-associated cognitive impairment. Further studies are needed to determine the true prevalence of HIV dementia in sub-Saharan Africa and to establish whether specific clade subtypes might influence the presentation of neurological complications.