Some studies have suggested that people who are younger when they enter puberty are more likely to later develop multiple sclerosis. But the authors of a new study said their findings do not support a substantial role for the effect of the timing of puberty on the risk of MS independent of body mass index.

For the study, researchers at McGill University in Montreal, Canada, looked at a genomewide association study of 329,245 women and 372 genetic variants that are strongly linked with the age when girls have their first menstrual cycle. Then researchers looked at another genetic study that included 14,802 people with MS and compared them to 26,703 people who did not have the disease to examine whether the age of puberty was associated with risk of MS. 

The researchers said they did find that people with an earlier age of puberty were more likely to develop MS, but once they factored in BMI, the results were no longer significant. 

According to the researchers, more research is needed to determine whether decreasing rates of obesity could help to reduce the prevalence of MS. If so, this could be another important reason for public health initiatives to focus on lowering obesity rates.

The study is published in the journal Neurology.