Individuals who are obese in early adulthood face a heightened risk of developing multiple sclerosis (MS), according to new research conducted by Dr. Brent Richards of the Lady Davis Institute at the Jewish General Hospital, Quebec, Canada and colleagues, published in PLOS Medicine. This result provides further confirmation of previous observational studies that had suggested the existence of such a link. MS is a progressive neurological disorder which can lead to disability and death, involving damage to the myelin which surrounds nerves in the spinal cord and brain. Causes of the disease are poorly understood, although immune-mediated mechanisms are likely. Currently available treatments have only modest effects on the disease and its symptoms, which underlines the importance of identifying preventive measures.
The team, comprised of researchers in Canada and the UK, and led by Lauren Mokry, carried out a Mendelian randomization study in large population datasets to investigate whether genetically determined obesity was associated with increased risk of MS. Such a study decreases the probability that exposures linked to obesity, such as smoking, can explain the findings. They found that a change in body mass index from overweight to obese (equivalent to an average size adult woman increasing in weight from 150 to 180 pounds) was associated with an increase of about 40% in the risk of MS.
"These findings may carry important public health implications because of the high prevalence of obesity in many countries" note the authors in their research article; "[because the] median age of onset for MS is 28-31 years ... [these findings should provide motivation] to combat increasing youth obesity rates by implementing community and school-based interventions that promote physical activity and nutrition."
In a Perspective discussing the research, Alberto Ascherio and Kassandra L. Munger note that, factoring in earlier research, Richards and colleagues' study "suggest[s] that obesity in early life is indeed causally related to multiple sclerosis risk and provide[s] a further rationale for obesity prevention."
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Lauren E. Mokry et al. Obesity and Multiple Sclerosis: A Mendelian Randomization Study, PLOS Medicine (2016). DOI: 10.1371/journal.pmed.1002053