MONDAY, Aug. 4, 2014 (HealthDay News) -- People with HIV seem to have a much lower risk of developing multiple sclerosis (MS) than those who don't have the virus, a new study finds.
This lower risk may be due to constant suppression of the immune system due to the HIV infection itself and/or the antiretroviral drugs used to treat the infection, according to the researchers.
They said their findings could prove important in finding new ways to treat MS, a degenerative nervous system disease.
The hospital study observed more than 21,000 HIV patients and nearly 5.3 million people in England who were followed for seven years. During that time, just seven people were diagnosed with MS instead of the expected 18 people. That means people with HIV seemed to be about 60 percent less likely to develop MS compared to those who didn't have HIV.
The longer a person had HIV, the less likely they were to develop MS. Compared to people in the general population, the risk of MS was 75 percent lower among people who had tested positive for HIV more than a year ago. The risk of MS was 85 percent lower among those who had tested positive for HIV more than five years ago.
Although this study linked HIV infection to a lower risk of MS, it wasn't able to prove that the HIV infection or treatments for HIV were the cause of the reduced risk.
"If subsequent studies demonstrate there is a causal protective effect of HIV and/or its treatment, and if the magnitude of it proves to be similar, this would be the largest protective effect of any factor yet observed in relation to the development of MS," wrote the study's authors.
Findings from the study were published online Aug. 4 in the Journal of Neurology Neurosurgery & Psychiatry.
This study adds to evidence suggesting a link between HIV infection and treatment and MS, but further research is needed to confirm this connection, Mia van der Kop, an epidemiologist at the University of British Columbia in Canada, wrote in an accompanying editorial.
The U.S. National Library of Medicine has more about multiple sclerosis.