HIV subtype linked to increased likelihood for dementia

Aug 28, 2009

Patients infected with a particular subtype of HIV, the virus that causes AIDS, are more likely to develop dementia than patients with other subtypes, a study led by Johns Hopkins researchers shows. The finding, reported in the September Clinical Infectious Diseases, is the first to demonstrate that the specific type of HIV has any effect on cognitive impairment, one of the most common complications of uncontrolled HIV infection.

HIV occurs in multiple forms, distinguished by small differences in the virus' and designated by letters A through K. Certain subtypes appear to cluster in particular areas of the world, and others have been associated with different rates of progression to full blown AIDS. Of the 35 million people living worldwide with HIV, the majority live in sub-Saharan Africa, where subtypes A, C and D dominate.

Nearly half of patients with advanced HIV infections have at least mild cognitive impairments, and about 5 percent have the severe form of cognitive impairment known as .

In earlier research, Ned Sacktor, M.D., and his colleagues found that about 31 percent of patients visiting an infectious disease clinic in the Ugandan capital, Kampala, where subtypes A and D dominate, had dementia. The finding led him and his team to wonder whether patients with different subtypes had different rates of dementia.

Sacktor, professor of neurology at the Johns Hopkins University School of Medicine and a clinician at the Johns Hopkins Bayview Medical Center, and his colleagues studied 60 HIV-infected patients from a Kampala clinic. All of the subjects had been part of a different study testing the effect of anti-retroviral drugs on , 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 each patient's brain function.

As expected, the majority of the patients had subtypes A or D. Out of the 33 subtype A patients, the researchers determined that seven had dementia, or about 24 percent. However, out of the nine patients with subtype D, 8 had dementia, about 89 percent.

"We were amazed to see such a dramatic difference in dementia frequencies between these two subtypes," Sacktor says. "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."

The research suggests that some biological property of each subtype seems to influence the likelihood that infected patients will develop dementia, says Sacktor. He and his team hypothesize that subtype D may cause more inflammation and injury in the brain, a possibility they are currently investigating.

Source: Johns Hopkins Medical Institutions

Explore further: South African "Mentor Mothers" lower HIV infection rates among pregnant women

add to favorites email to friend print save as pdf

Related Stories

Challenges of HIV-1 subtype diversity

May 21, 2008

A review article in the New England Journal of Medicine explores the genetic variation of HIV-1 and its implications for preventing and treating the disease. Francine McCutchan, Ph.D., a researcher with the U.S. Military HIV Re ...

Studies suggest HIV subtype more deadly than others

Nov 27, 2007

Two studies led by researchers at the Johns Hopkins Bloomberg School of Public Health found that people infected with HIV in Thailand die from the disease significantly sooner than those with HIV living in other parts of ...

Study sheds light on causes of HIV dementia

Dec 03, 2008

A new study led by researchers at Albert Einstein College of Medicine of Yeshiva University has clarified how two major variants of HIV differ in their ability to cause neurologic complications. The finding, ...

Analysis of Chinese AIDS epidemic shows surprising patterns

Feb 09, 2007

The mountainous Chinese province of Yunnan is tucked into the country’s southwest corner, a scenic region that borders Burma, Laos and Vietnam. The province shares its rugged topography with the surrounding countries, but ...

Herpes drug inhibits HIV replication, but with a price

Nov 06, 2008

The anti-herpes drug acyclovir can also directly slow down HIV infection by targeting the reverse transcriptase (RT) enzyme, researchers report in this week's JBC. This beneficial effect does pose a risk though, as HIV-in ...

Recommended for you

Obese British man in court fight for surgery

Jul 11, 2011

A British man weighing 22 stone (139 kilograms, 306 pounds) launched a court appeal Monday against a decision to refuse him state-funded obesity surgery because he is not fat enough.

2008 crisis spurred rise in suicides in Europe

Jul 08, 2011

The financial crisis that began to hit Europe in mid-2008 reversed a steady, years-long fall in suicides among people of working age, according to a letter published on Friday by The Lancet.

New food labels dished up to keep Europe healthy

Jul 06, 2011

A groundbreaking deal on compulsory new food labels Wednesday is set to give Europeans clear information on the nutritional and energy content of products, as well as country of origin.

Overweight men have poorer sperm count

Jul 04, 2011

Overweight or obese men, like their female counterparts, have a lower chance of becoming a parent, according to a comparison of sperm quality presented at a European fertility meeting Monday.

User comments : 0