Obese girls are at greater risk of developing MS, according to a new study. Researchers looked at body mass index (BMI) data from more than 900,000 children from the Kaiser Permanente Southern California Children's health study. Seventy-five of those children and adolescents between the ages of 2 and 18 were diagnosed with pediatric MS. More than 50 percent of them were overweight or obese (compared to 36.6 percent of the children who did not have MS) and the majority of them were girls.
According to the study, the MS risk was more than one and a half times higher for overweight girls, almost two times higher in moderately obese girls, and almost four times higher in extremely obese girls. The association between weight and MS was only seen in girls, and was greater in Hispanic girls in particular.
"In our study, the risk of pediatric MS was highest among moderately and extremely obese teenage girls, suggesting that the rate of pediatric MS cases is likely to increase as the childhood obesity epidemic continues," the authors wrote, noting that over the last 30 years, childhood obesity has tripled.
“Menstrual cycle levels of female sex steroids have been shown to increase the risk of MS in animal models by promoting inflammatory mediators of autoimmunity,” explained study author Dr. Annette Langer-Gould, of the Kaiser Permanente Southern California Department of Research & Evaluation inPasadena.
Fat tissue also produces these pro-inflammatory mediators.
“We speculate that these extremely obese peri-pubescent girls are getting a double dose of pro-inflammatory mediators and thereby increasing their risk of MS and MS-like illnesses,” she said.
The study found no association in boys, but the authors suspect that the effects of obesity may show up later in men, as they reach young adulthood.
Even though pediatric MS remains rare—1.7 in 100,000 kids—parents of obese teenagers should pay attention to symptoms such as collapsing weakness in the legs after modest exertion, pain and loss of vision in one eye, tingling and numbness, limb weakness and loss of bladder control. If these symptoms arise, the child should be examined by a neurologist, Langer-Gould said.
The study was published in the online issue of the journal Neurology