Research: is obesity related to childhood MS?

Langer Gould A, Brara SM, Beaber BE, Koebnick C: (epub) Childhood obesity and risk of pediatric multiple sclerosis and clinically isolated syndrome Neurology 2013

OBJECTIVE:To determine whether childhood obesity is a risk factor for developing pediatric multiple sclerosis (MS) or clinically isolated syndrome (CIS).
METHODS:Cases were identified through the Kaiser Permanente Southern California (KPSC) Pediatric Acquired Demyelinating Diseases Cohort between 2004 and 2010. For cases, body mass index (BMI) was obtained prior to symptom onset, for the underlying cohort BMI was obtained through the KPSC Children's health study (n = 913,097). Weight classes of normal weight, overweight, moderate obesity, and extreme obesity were assigned based on BMI specific for age and sex.
RESULTS:We identified 75 newly diagnosed pediatric cases of MS or CIS, the majority of which were in girls (n = 41, 55%), age 11-18 (n = 54, 72%). Obesity was associated with a significantly increased risk of MS/CIS in girls (p = 0.005 for trend) but not in boys (p = 0.93). The adjusted odds ratio and 95% confidence intervals for CIS/MS among girls was 1.58 (0.71-3.50) for overweight compared to normal weight (reference category), 1.78 (0.70-4.49) for moderately obese, and 3.76 (1.54-9.16) for extremely obese. Moderately and extremely obese cases were more likely to present with transverse myelitis compared with normal/overweight children (p = 0.003).
CONCLUSION:Our findings suggest the childhood obesity epidemic is likely to lead to increased morbidity from MS/CIS, particularly in adolescent girls.

This is an observational study, which does not shed light on the reasons behind this trend. The authors took care to ensure that weight was measured prior to MS symptom development, meaning that the weight increase is not a result of the disability caused by MS. If reproduced, then it hints at a shared factor that can be seen in both obesity and childhood MS. There are studies examining this in people with adult MS, and the results seem to indicate that increased body mass index (BMI) in late adolescence is associated with an increase in MS risk. At the moment, there is no indication as to the cause of this link. Could it be vitamin D - there is an association between increased BMI and low vitamin D levels, although this theory is purely speculative!