Children who are obese face double the odds of developing multiple sclerosis later in life, a new study warns.

The overall odds for any one child to develop the neurodegenerative illness remains very low. However, the Swedish researchers believe the link could help explain rising rates of MS.

"There are several studies showing that MS has increased over several decades and obesity is believed to be one major driver for this increase," wrote a team led by Claude Marcus, of the Karolinska Institute in Stockholm. "Thanks to our prospective study design, we can confirm this theory."

The findings will be presented in May at the European Congress on Obesity in Venice.

For the study, Marcus and his colleagues tracked data from 1995 through 2020, compiled by the Swedish Childhood Obesity Treatment Register.

Almost 22,000 children were covered by that database, and their incidence of MS later in life was compared to that of similar, non-obese children from the general Swedish population. Rates of cases of newly diagnosed MS were tracked till 2023.

The result: While 0.06% of the non-obese children went on to develop MS, the rate more than doubled, to 0.13%, among people who had been obese during childhood.

Two-thirds of cases occurred in females, the study found, which mimics the general ratio of MS observed in women compared to men.

MS was diagnosed at roughly the same average age — about 23 — regardless of people's weight history, the team added.

How might being obese in childhood raise a person's odds for MS?

"Paediatric obesity is associated with several autoimmune diseases and the leading hypothesis is that the persistent low-grade inflammatory state, typically observed in obesity, is mediating the association," Marcus' group theorized.

They stressed, however, that the absolute risk to any one child with obesity going on to develop MS is still very low.

Because these findings will be presented at a medical meeting, they should be considered preliminary until published in a peer-reviewed journal.