A study of more than 700 patients with eating disorders (ED) found significantly higher average IQs among participants, compared with the general population.
Researchers from the Netherlands analyzed IQ scores and ED severity among 703 adolescents and adults. Their findings are published online in the International Journal of Eating Disorders.
The team measured participants’ intelligence using the Wechsler's Full scale IQ (FSIQ), Verbal IQ (VIQ) and Performance IQ (PIQ) tests. The associations between IQ and ED were analyzed using body mass index, length of ED duration and Eating Disorder Inventory [ED-II] ratings.
The mean IQs of the ED patients were significantly higher than general population means, and effect-sizes were small to medium.
No linear associations were found between IQ and BMI, but PIQ score was associated with psychological/behavioral severity of the ED in adult patients with anorexia nervosa.
“Our findings suggest that, in contrast with other severe mental disorders where low intelligence is a risk factor, higher than average intelligence might increase the vulnerability to develop an ED,” wrote Christina M.T. Schilder, PhD, and colleagues.
The association between ED and above-normal intelligence has been cited in small studies previously, but larger studies are lacking and the link has not been studied thoroughly, the researchers said.
Schilder CMT, van Elburg AA, Snellen WM, et al. Intellectual functioning of adolescent and adult patients with eating disorders. International Journal of Eating Disorders. 2016 August 16;[Epub ahead of print].