Brain Changes from Eating Disorders Mirror Those Seen in OCD and Autism

New research indicates that children with anorexia nervosa are undergoing significant brain changes that go beyond what starvation can explain. This insight helps clarify the neurological mechanisms behind the disorder, potentially paving the way for improved treatment strategies.

Anorexia nervosa is noted for severe dietary restrictions and a distorted body image, making it a less understood condition. While previous studies have highlighted that the brain’s outer layer, or cortex, is notably thinner in these individuals, it remains uncertain whether such changes stem from malnutrition or are intrinsic to anorexia.

Clara Morrow from The University of Montreal, Canada, examined brain scans of children with anorexia alongside those with Avoidant/Restrictive Food Intake Disorder (ARFID). Although both conditions encompass significant food restrictions and weight loss, ARFID lacks the body image concerns that characterize anorexia. Instead, individuals with ARFID may avoid food due to sensory sensitivities, disinterest in eating, or fear of adverse consequences like choking, vomiting, or gastrointestinal distress. The comparison could shed light on the unique brain changes associated with each condition and malnutrition, according to Moreau.

The study analyzed brain scans from 124 children diagnosed with anorexia, 50 with ARFID, and 116 without eating disorders. All participants were under 13 years old and resided in France. Researchers examined the extent of brain differences between those with and without eating disorders.

On average, children diagnosed with anorexia exhibited a significantly thinner cortex compared to those without eating disorders. Once body mass index (BMI) was taken into account, anorexia correlated with cortical thinning across 32 brain regions, particularly in the superior head lobule, an area involved in sensory information processing. “This aligns with our understanding, as we know anorexic patients often struggle with their perception of weight and size,” stated team member Anael Ayrolles from the University of Paris.

These alterations are akin to those observed in older adolescents and adults suffering from anorexia, notes Moreau. “The effect size is among the most significant in psychiatry,” she comments. “It appears as if they’ve experienced accelerated brain aging or early Alzheimer’s disease, though they show no symptoms of Alzheimer’s. However, if their BMI is normalized, brain recovery is often observed, though not in every case.”

In contrast, no significant differences in cortical thickness were observed between children with ARFID and those without any eating disorders. “We anticipated some overlap with anorexia potentially reflective of BMI,” explains Moreau. “However, our findings did not reveal many similarities between the two conditions.” The reason for this remains unclear, especially since this is the inaugural brain imaging study focused on ARFID. Given that ARFID typically manifests before the age of five, the brain may have adapted to limited food intake, suggests Moreau.

The researchers subsequently contrasted these brain differences with findings from previous studies on other disorders, including obsessive-compulsive disorder (OCD), ADHD, and autism. They found a notable correlation between anorexia and OCD, whereas ARFID displayed brain changes similar to those associated with autism. This aligns with Moreau’s assertion that sensory sensitivity is prevalent in both autism and ARFID. Conversely, OCD and anorexia exhibit obsessions, rituals, and preconceived notions.

Nevertheless, individuals with OCD and anorexia frequently present other mental health challenges, notes Joanna Steinglass from Columbia University in New York. Approximately 14% of those diagnosed with anorexia also meet the criteria for OCD. This complicates the understanding of whether a genuine neurological resemblance exists between the two conditions or if other mental health challenges underpin this correlation.

“We were cautious not to over-interpret our results,” said Ayrolles. However, these discoveries imply that malnutrition alone may not account for all the brain changes observed in anorexia. “Mental illness is fundamentally a brain-based illness, and understanding this helps us address patient experiences more effectively, often leading to less blame,” remarks Steinglass. “This insight could drive the development of more effective treatments.”