High rates of child and teen obesity could play a growing role in people's risk for multiple sclerosis (MS), British researchers say.
Prior research has suggested that 53% of MS risk is directly attributable to environmental factors. For example, up to 1 in 5 cases could be attributed to smoking, the research team noted.
Increasingly, obesity is also a big risk factor for the neurological disorder, the new global study found.
Researchers analyzed data from four countries -- the United States, Britain, Australia and Russia -- to estimate how much MS risk could be attributed to two modifiable risk factors, youth obesity and smoking. Overall, the data included almost 15,000 people with MS and almost 580,000 without.
The study was led by Ruth Dobson, a consulting neurologist and lecturer at Queen Mary University of London. Her team found that in 2015, youth obesity was linked to 11% of MS cases in the United States; 9% in Australia; 8% in Britain; and 4% of cases in Russia.
Rising obesity rates among the young worldwide also mean that by 2035, those numbers are projected to hit 14% in the United States; 11% in Australia; 10% in Britain and 6% in Russia, according to the new study published Aug. 26 in the International Journal of Epidemiology.
But there's still the "potential to reduce the incidence of MS worldwide with targeted public health strategies," Dobson noted in a university news release. If it's confirmed that youth obesity contributes to MS risk later on, reducing obesity in kids and teens could reduce MS incidence, as well as other obesity-related diseases, she and her colleagues said.
The study also found that in 2015, about 10% of MS risk could be linked to smoking, but said that will decline as smoking rates fall. On the other hand, obesity-related MS risk is on the rise due to increasing rates of weight gain.
"It is not only cancer and heart disease that are influenced by smoking and obesity," Dobson said. "Shifting the focus to diseases with onset in early adulthood, such as MS, may resonate more with younger people whose lifestyle choices will have an impact on their risk of future illness."
Dr. Asaff Harel is a neurologist at Lenox Hill Hospital in New York City. Reading over the new report, he said that "we know that there are many genetic and environmental factors" driving MS.
And while the study can't prove cause and effect, "reductions in early-life obesity and smoking would be beneficial from not only the MS standpoint, but the general health standpoint as well," Harel said.
The American Academy of Family Physicians has more on multiple sclerosis.