HIV Linked to Reduced Risk of Developing Multiple Sclerosis

Drugs used to treat human immunodeficiency virus (HIV) could potentially used to treat multiple sclerosis (MS), as research has indicated people with HIV have a lower risk for MS, suggested findings originally published online in August, but appearing in the January 2015 edition of the Journal of Neurology, Neurosurgery, and Psychiatry.

Researchers from the United Kingdom conducted a comparative cohort study which accessed more than 21,000 HIV positive patients and more than 5 million control subjects in order to investigate the possible association between HIV and MS. There was only a single case of an HIV positive patient with MS being treated with HIV antiretroviral therapies at the time the researchers began their study, but the patient’s symptoms resolved completely after antiretroviral therapy. The patient remained subsided for more than 12 years, which researchers have hypothesized was due to the pathogenesis of MS and the ability of antiretroviral therapy to coincidentally treat or prevent the progression of MS.

Before the current research began, Danish researchers conducted an epidemiological study on the incidence of MS in a newly diagnosed HIV population. Those researchers examined 5,018 HIV cases and compared the patients to 31,875 controls. After a follow up period of 393,871 person years, the incidence rate ratio for an HIV patient developing MS was 0.3. The researchers considered this ratio low, but it did not reach statistical significance maybe because of the small numbers in both groups.

The researchers compared the HIV positive patients to the control subjects and stratified the groups by age, sex, year of first hospital admission, region of residence, and socioeconomic status. The researchers found the overall rate ratio of developing MS in HIV positive patients, relative to those who were HIV negative, was 0.38.

“HIV infection is associated with a significantly decreased risk of developing MS,” the authors concluded, while adding that their results were consistent with the Danish study. “Mechanisms of this observed possibly protective association may include immunosuppression induced by chronic HIV infection and antiretroviral medications.”

The authors continued by saying that is subsequent studies consistently reported an incidence rate ratio of about 0.38, it would be the largest protective effect of any factor yet observed in relation to the development of MS. Prior studies have demonstrated that other factors like smoking, specific gene markers, vitamin D deficiency, and many viruses can contribute to increasing the risk of developing or progressing MS compared to controls. However, not having these risk factors may not be protective of the risk, the researchers cautioned.