A recent study in Clinical Infectious Diseases found that HIV-infected individuals with subtype D virus, which refers to the HIV virus commonly found in Eastern and Central Africa, had a higher risk of dementia, when compared to subtype A, which refers to the virus commonly found in West Africa.

Dementia is a condition in which severe mental ability loss, such as in memory capacity, deteriorates an individual’s ability to function normally.

The study examined the relationship between different HIV subtypes and cognitive impairment in individuals beginning antiretroviral treatment. In the study, sixty treatment naïve individuals with immunosuppression (reduced immune system response) and signs of cognitive impairment were assessed through a series of neurological, neurophysiological, and functional tests.

Thirty-three individuals were infected with subtype A, two with subtype C, nine with subtype D, and 16 with A/D recombinants (combination of A and D virus sequences). Results showed that eight of the nine individuals (or 89 percent) infected with subtype D showed signs of dementia. In comparison, seven of 33 individuals (or 24 percent) infected with subtype A displayed signs of dementia.

HIV subtypes A and C are the most widespread. Subtypes A, C, and D are common in sub-Saharan Africa, while subtype B is common in United States.

This study is the first to show that HIV subtypes can cause cognitive impairment. Additional studies are necessary to support these findings and further define the relationship between subtypes of HIV and cognitive impairment.

For more information, please see the study in Clinical Infectious Diseases (abstract).