At least 20 percent of adults and 3 percent of children with eating disorders also have autism. But much of what researchers know about link between the two conditions has come from studies of people seeking treatment for eating disorders, which makes it difficult to understand whether one condition sets the stage for the other or something else explains the overlap.
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To investigate whether autism traits precede disordered eating, [researcher Francesca] Solmi and her colleagues analyzed data from the Avon Longitudinal Study of Parents and Children, which tracks nearly 14,000 people born in Bristol, England, in 1991 and 1992.
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The researchers found that adolescents with disordered eating habits had more autism traits at ages 7, 11 and 14, suggesting that these traits raise the odds of developing an eating disorder. And the more autism traits a teenager had, the more frequent her disordered eating behaviors.
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The emergence of disordered eating may be related to the social stresses of adolescence, Solmi says, and that stress can be particularly intense for people with autism traits.
“If you have difficulties relating to your peers, this might result in feelings of anxiety or depression,” Solmi says. “In the case of eating disorders, it could be that eating then becomes one way in which people cope.”
Other experts say further work is needed to understand the mechanisms underlying both social difficulties and eating disorders. It is likely that they share common biology, rather than one condition causing the other.