Pediatric-Onset MS Linked to Obesity

January 30, 2013

Childhood obesity was independently associated with an increased risk of pediatric onset of multiple sclerosis (MS) or clinically isolated syndrome (CIS) in girls but not boys in a new study.

"Our results should be interpreted as another reason to try and reduce obesity in young girls," lead author, Annette M. Langer-Gould, MD, from Kaiser Permanente Southern California (KPSC), Pasadena, told Medscape Medical News.

In the paper, published online January 30 in Neurology, the authors conclude, "These findings suggest that the risk of pediatric MS/CIS is highest among moderately and extremely obese teenage girls, implying that the incidence of pediatric MS/CIS is likely to increase as the childhood obesity epidemic continues."

Dr. Langer-Gould added. "If there is MS in the family, i would advise being extra careful to keep weight in check in adolescent girls."

Clear Dose Response

For the study, Dr. Langer-Gould and colleagues analyzed the relationship between obesity and MS/CIS in 900,000 children, members of the KPSC health maintenance organization.

The researchers identified 75 newly diagnosed pediatric cases of MS or CIS in 41 girls and 34 boys. Of these children with MS/CIS, 51% were overweight or obese. Obesity was associated with a significantly increased risk for pediatric MS/CIS in girls (P for trend = .005) but not for boys (P for trend = 0.93).

In addition, a clear dose response was seen in girls, with the risk for MS increasing with the degree of obesity, whereas this was not seen in boys.

Table. Risk for Pediatric MS/CIS With Increasing Weight Class

Class Odds Ratio in Girls Odds Ratio in Boys
Underweight/normal weight 1 1
Overweight 1.58 1.80
Moderate obesity 1.78 0.89
Extreme obesity 3.76 0.82

 

Speculating on the mechanism, Dr. Langer-Gould said this relationship may involve hormonal changes.

"Something is happening at puberty. It may be to do with the female hormones or something in the x chromosome," she said. "There are increased estrogen levels in both sexes in obesity. But estrogen levels will be much at puberty higher in girls than in boys. The combination of puberty and obesity can lead to very high estrogen levels in girls."

In the paper, the researchers expand on this idea, suggesting that the rapid rise and high estrogen exposure of obese, peripubescent girls in combination with the inflammatory mediators released by adipose tissue accelerate CIS/MS onset into adolescence. In contrast, raised estrogen levels in obese boys could lead to a raised lifetime risk for MS/CIS; however, because estrogen levels never reach those seen in obese girls, symptom onset is usually delayed into adulthood.

Dr. Langer-Gould noted that unfortunately just measuring blood estrogen levels may not be sufficient to prove this hypothesis, as estrogens can be stored in adipose tissue. As result, MS incidence may not correlate with levels found in a simple blood test.

The researchers call for further studies that follow children into adulthood to address these ideas further.

The study was supported by the National Institute of Diabetes and Digestive and Kidney Disorders and Kaiser Permanente Direct Community Benefit Funds.

Neurology. 2013;80:548-552. Published online January 30, 2013. Abstract

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