LONDON, April 21 (UPI) -- Girls are more likely to be diagnosed with an eating disorder at schools with more female students and higher proportions of college-educated parents, according to a study of children in Sweden.
Even after accounting for other variables that could influence an eating disorder, researchers at five universities in England and Sweden found the two factors increased the number of girls with disorders, though they are not entirely sure why.
The researchers speculate explanations ranging from an aspirational culture to the disorders being contagious -- or maybe some schools are better at identifying students with eating disorders, they say.
The study raises concerns because there are no single sex schools in Sweden, unlike the United Kingdom or the United States, suggesting rates of eating disorders could be worse in all-girls schools.
"Our study suggests that eating disorders are more common in some schools than others," Glyn Lewis, a professor of psychiatry at University College London, said in a press release. "We cannot be sure why this happens, but the worst affected schools had a higher proportion of girls and more highly educated mothers. We don't know if these results from Sweden will also apply to schools in the United Kingdom but it is a concern that we have a number of highly academic, single sex, girls' schools in the United Kingdom. Eating disorders can be very serious and disabling, often affecting young women at a crucial time of their life and with long-lasting effects on their well-being."
For the study, published in the International Journal of Epidemiology, researchers analyzed data on 55,059 females born in 1983 who finished high school between 2002 and 2010 in Sweden.
The five-year incidence of eating disorders among the girls between ages 16 and 20 was 2.4 percent. For each 10 percent increase in proportion of girls at a school and 10 percent increase in proportion of children with at least one college-educated parent, the odds of an eating disorder increased.
This means that at a school where 25 percent of the population is girls and 25 percent of parents have degrees, there is a 1.3 percent chance of an average girls developing a disorder, compared to 3.3 percent risk for girls a school with 75 percent girls and 75 percent of parents with a degree.
"Eating disorders have an enormous effect on the lives of young people who suffer from them -- it is important to understand the risk factors so that we can address them," Dr. Helen Bould, a child and adolescent psychiatrist at the University of Oxford, said in a press release. "For a long time clinicians in the field have noted that they seem to see more young people with eating disorders from some schools than others, but this is the first empirical evidence that this is the case."