Other Subtypes May Affect Disease Outcomes Too
• Science Update
In a study of HIV-related cognitive impairment in Uganda, people with HIV subtype D were more likely than those with the other subtypes to have HIV-associated dementia (HAD), according to NIMH-funded researchers. This study, published in the September 1, 2009, issue of Clinical Infectious Diseases, is the first to show that HIV subtype may affect a person's risk for developing HAD.
HIV-associated dementia is a common symptom of advanced HIV infection, affecting a person's central nervous system and cognitive skills. While the subtype of HIV has been shown to affect the progression of HIV to AIDS, the effect on HAD risk has been unknown.
To explore this relationship, Ned Sacktor, M.D., of Johns Hopkins Bayview Medical Center, and colleagues conducted a study in Uganda of 60 people at risk of developing HAD. The wide variety of HIV subtypes in Uganda and other sub-Saharan countries, along with studies suggesting a relatively high prevalence of HAD and other HIV-related neurological complications in these regions, makes them ideal locations for studying the effects of HIV subtypes on various disease outcomes.
All participants in Sacktor's study had advanced HIV infection but had not previously received highly active antiretroviral treatment (HAART), the current standard of care for HIV. The researchers assessed participants' neurological, neuropsychological, and functional status, as well as their HIV subtype.
Results of the Study
Of the 60 study participants:
- 33 were infected with subtype A
- 2 were infected with subtype C
- 9 were infected with subtype D
- 16 were infected with a subtype that had characteristics of both subtype A and subtype D.
Participants with HIV subtype D were more likely to have HAD (89 percent with dementia) than those with subtype A (24 percent with dementia). The two other HIV subtypes observed in the study did not show a significant association with HAD.
The results suggest that among people with advanced HIV infection, those with subtype D are more likely to have HAD than those with other subtypes. According to the researchers, these findings are the first to show that HIV subtypes may play a role in causing HAD.
More studies are needed to confirm whether the relationship between HIV subtype D and increased HAD risk exists among the broader HIV-infected community, instead of just those who had not previously received HAART. Additional research should also focus on how subtype D may lead to increased risk of HAD, and whether other subtypes may also influence risk for this and other HIV-related neurological complications.
Sacktor N, Nakasujja N, Skolasky RL, Rezapour M, Robertson K, Musisi S, Katabira E, Ronald A, Clifford DB, Laeyendecker O, Quinn TC. HIV subtype D is associated with dementia, compared with subtype A, in immunosuppressed individuals at risk of cognitive impairment in Kampala, Uganda . Clin Infect Dis. 2009 Sep 1;49(5):780-6. PubMed PMID: 19622045.