Understanding Eating Disorders and Their Genetic Roots

Recent research spearheaded by the University of North Carolina has uncovered significant evidence linking genetics to anorexia nervosa. Published in the journal Nature Genetics, this study reveals that not only does anorexia have a genetic basis, but it also involves distinct metabolic traits that complicate weight recovery after treatment.

Traditionally, discussions around eating disorders like anorexia have centered on psychological and social influences, often framing it as a learned behavior or a reaction to external pressures. However, the familial nature of the disorder raises questions about hereditary risks, akin to those seen in conditions such as breast cancer and Alzheimer’s disease.

For years, the field of psychiatric genetics struggled to establish a genetic link to anorexia due to limited sample sizes. Anorexia nervosa impacts approximately 0.6% of the U.S. population, making it challenging to collect sufficient DNA samples for robust statistical analysis. The disorder's high mortality rate, estimated at around 6%, necessitates further research, especially when compared to the 15% mortality rate associated with substance use disorders.

In the UNC study, researchers identified eight genetic markers that may increase the risk of developing anorexia nervosa. Notably, some of these markers are also associated with other psychiatric conditions like depression and obsessive-compulsive disorder, suggesting a genetic overlap.

The most fascinating finding is the association of these genetic markers with low body mass index (BMI).

“This collection of genetic correlations indicates the need to explore two distinct categories of causal factors,” explains Dr. Cynthia Bulik, the study's lead author and director of the University of North Carolina Center of Excellence for Eating Disorders. “One category pertains to psychiatric elements, while the other relates to metabolic processes. The complexity of these factors is greater than we had anticipated.”

Individuals typically experience weight gain over time, yet those with anorexia nervosa frequently maintain low body weights even post-treatment. This situation complicates recovery efforts, leading to frustration for patients striving to adopt healthier eating habits, and concern among family members about potential relapses.

“We’ve long characterized this phenomenon as a psychological obsession with fitness,” Bulik states. “Our findings suggest we might need to consider metabolic influences as well.”

To carry out this study, Bulik collaborated with over 200 researchers worldwide, gathering data from nearly 17,000 anorexia patients across five countries: the U.S., Australia, New Zealand, Denmark, and Sweden, where she also directs the Centre for Eating Disorders Innovation at the Karolinska Institute in Stockholm.

The researchers then compared these individuals to a control group of over 55,000 individuals without the disorder, aiming to pinpoint significant genetic variations. This genome-wide association study is part of a broader initiative to investigate the genetic underpinnings of various psychiatric disorders.

Bulik hopes that a deeper understanding of anorexia as a metabolic condition may persuade insurance companies to extend coverage for inpatient treatment rather than terminating support once a patient reaches a specific BMI.

“When insurance companies discharge patients at BMIs like 17, the risk of relapse increases significantly since their metabolism hasn’t had time to stabilize,” she notes.

While the study marks a crucial step in identifying genetic risk factors and their potential effects on biological processes, Dr. Walter Kaye, a psychiatry professor at the University of California, San Diego, cautions that distinguishing between biological and psychosocial factors on an individual level remains complex.

“For certain individuals, genetics may play a larger role, while for others, environmental factors may be more significant,” Kaye explains. “The intricacies of this issue are more involved than we initially believed.”

Bulik's dataset is part of the broader Psychiatric Genomics Consortium, established in 2007, which brings together researchers, clinicians, and genetic data from around the globe to further understand a range of mental health disorders, including ADHD, bipolar disorder, depression, and schizophrenia.

Bulik expresses hope that continued exploration of the biological pathways linking these genetic factors to anorexia will eventually pave the way for drug therapies targeting the metabolic aspects of the disorder.

“At present, we lack effective medications for treating this illness, partly due to our limited understanding of the biology involved,” she states. “In the future, this research may lead to new avenues for drug development.”

The first video, Genes, Environment, and Eating Disorders: Accelerating Science Through Global Collaboration, delves into how genetic and environmental factors interplay in the context of eating disorders, emphasizing the importance of global cooperation in advancing research.

The second video, Innovative Approaches to Understanding Eating Disorders, showcases cutting-edge methods being employed to enhance our understanding of eating disorders, including genetic insights and novel treatment modalities.