Researchers believe that patients infected with HIV subtype D are more likely to develop dementia than those with other types. Although the reasons behind it are still unknown, the Johns Hopkins led team is investigating whether subtype D causes more inflammation and injury in the brain, which could explain the related dementia.
In earlier research, Ned Sacktor, M.D., and his colleagues found that about 31% of patients visiting an infectious disease clinic in Kampala, Uganda, where subtypes A and D dominate, had dementia. This led him and his team to wonder whether patients with different subtypes had different rates of dementia.
Dr. Sacktor, professor of neurology at the Johns Hopkins University School of Medicine and a clinician at the Johns Hopkins Bayview Medical Center, studied 60 HIV-infected patients from a Kampala clinic. All the subjects had been part of a different study testing the effects of anti-retroviral drugs on cognitive impairment but had not begun taking the drugs. After determining each patient's HIV subtype, they performed a battery of neurological and cognitive tests to assess their brain function.
Most patients had HIV subtypes A or D. Out of the 33 subtype A patients, the researchers determined that seven had dementia, or about 21%. Out of the nine patients with subtype D, 8 had dementia, or about 89%. The findings will be reported in the September issue of Clinical Infectious Diseases.
“We were amazed to see such a dramatic difference in dementia frequencies between these two subtypes,” says Dr. Sacktor. “If this is the case in all of sub-Saharan Africa, HIV-associated dementia may be one of the most common but thus far unrecognized, dementias worldwide.”