Over the past decade, several case studies have documented instances where individuals with multiple sclerosis (MS), upon initiating antiretroviral therapy for HIV (aimed at controlling the virus), observed a complete disappearance of their MS symptoms or a significant slowing of disease progression.
These findings prompted researchers to explore whether HIV or antiretrovirals could impact the likelihood of developing MS. Our most recent study, published in the Annals of Neurology, confirms that the answer is affirmative.
Determining whether HIV or antiretroviral drugs could impact MS is challenging due to the need to follow large groups of people living with HIV, possessing detailed medical information on both HIV and MS, over an extended period.
Three prior studies attempted to address this question, but they were hindered by either a small number of patients or a lack of access to information on antiretroviral treatment. As a result, earlier research did not offer conclusive answers.
For this research, we leveraged extensive population-based health databases along with clinical HIV and MS registries, encompassing nearly every individual in British Columbia, Canada, and Sweden officially identified as HIV-positive, dating back to 1992 in Canada and 2001 in Sweden.
We tracked individuals with HIV from the initial acknowledgment of their HIV infection until the conclusion of the study period (2020 in Canada and 2018 in Sweden). New cases of MS during this timeframe were identified through data from hospitals, medical practitioners, and insights gathered from specialized MS clinics.
We examined the incidence of new MS cases among individuals with HIV and compared it to the rate of new cases in the general population within each respective region. This comparison aimed to ascertain whether there was indeed a distinct risk of MS in people with HIV.
We identified a cohort of more than 29,000 individuals with HIV and monitored them for an average of almost ten years. During this timeframe, only 14 individuals with HIV developed MS, representing a 47% reduction in cases compared to the expected numbers based on the general population.
Upon closer examination of individuals who had taken antiretroviral drugs (which comprised nearly everyone in the study), and specifically after initiating antiretroviral therapy, we observed a 45% reduction in MS cases compared to the expected numbers. In other words, we identified a diminished risk among individuals who were HIV-positive and had undergone antiretroviral therapy.
For women, the risk of developing MS was notably decreased, showing a reduction of 72%. Among men in the HIV-positive population, there were also fewer cases of MS than expected, although the difference in risk reduction was less prominent compared to women.
Possible biological explanation
Based on the findings of this study alone, it remains unclear whether the virus or antiretroviral therapy is responsible for the observed reduction in MS risk. However, there are biological reasons supporting both theories.
HIV results in a gradual decline of immune cells known as CD4+ T cells. These cells are also involved in MS, triggering a series of events leading to inflammation in the brain and spinal cord. Infection with HIV, by decreasing CD4+ T cell counts, may lower the chances of a person developing MS.
The discovery that the risk of MS is reduced when the HIV is likely controlled by antiretroviral drugs provides a glimmer of hope, suggesting that it may be the treatment rather than the virus itself that influences this effect.
Antiretrovirals may reduce the risk and disability of MS through potential mechanisms, including the inhibition of the Epstein-Barr virus. Growing research underscores the significant role of Epstein-Barr in MS.
The antiviral effects of HIV therapy could potentially restrict Epstein-Barr virus activity, reducing the risk of developing MS and slowing disease progression in those already affected.
The discovery that HIV infection or antiretroviral drugs provide a protective effect against MS has the potential to enhance our understanding of MS causes and how the disease impacts the body.
While treatments exist for the relapsing form of MS, none can effectively stop the continuous progression observed in the later stages of the disease. The results of this study could inspire a more focused exploration into whether antiretroviral drugs might impede the progression of MS.
Given the constraints on research resources, adopting this approach could offer more immediate benefits by addressing the significant unmet need for the development of improved treatments focused on preventing or slowing the progression of MS.
This article has been reissued from The Conversation under a Creative Commons license.
