Harvard researchers see genetic link between anorexia, early rising

New research has found an association between the eating disorder anorexia nervosa and early rising, unlike many other disorders, such as depression, binge eating disorder, and schizophrenia, that tend to be evening-based.

The study, published in JAMA Network Open and led by investigators at Harvard-affiliated Massachusetts General Hospital, in collaboration with University College London and the University of the Republic in Uruguay, also revealed a link between anorexia and insomnia risk.

Previous research had suggested a possible connection between eating disorders and the body’s internal, or circadian, clock, which controls a wide range of biological functions, including sleep, and affects nearly every organ in the body.

This study aimed to further understand this relationship by assessing genes associated with anorexia, the circadian clock, and several sleep traits, including insomnia.

The investigators used a statistical method called Mendelian randomization to see how genes that are associated with a given trait affect other traits of interest. For example, examining the sleep patterns of people with genetic differences that make them likelier to have anorexia provides evidence of the its relationship with sleep.

The scientists found a two-way association between anorexia-related genes and those associated with the morning chronotype, which means waking early and going to bed early. In other words, the findings suggest that being an early riser could increase the risk of anorexia nervosa, and having anorexia nervosa could lead to an earlier wake time. The team also found an association between anorexia nervosa and insomnia.

52% relapse rate of current
treatments for anorexia

When they further assessed the insomnia connection using the Mass General Brigham Biobank by developing a “genetic risk score” for anorexia, the scientists confirmed that the genetic risk score was indeed associated with higher insomnia risk.

“Our findings implicate anorexia nervosa as a morning disorder, in contrast to most other evening-based psychiatric diseases, and support the association between anorexia nervosa and insomnia as seen in earlier studies,” says senior author Hassan S Dashti, an assistant investigator in the Department of Anesthesia, Critical Care, and Pain Medicine at MGH and an assistant professor of anesthesia at Harvard Medical School.

Treatments for anorexia nervosa are limited and current treatments have relapse rates of up to 52 percent. In addition, the cause of the disease is still unclear. But as the illness has the second-highest mortality rate of all psychiatric diseases, more research is desperately needed into new prevention strategies and treatments.

“The clinical implications of our new findings are currently unclear; however, our results could direct future investigations into circadian-based therapies for anorexia nervosa prevention and treatment,” said Hannah Wilcox, lead author of the study and researcher at MGH.

Additional authors include Valentina Paz, Richa Saxena, John W. Winkelman, and Victoria Garfield.

This research was supported by the National Institutes of Health.