A major study published in the journal Biological Psychiatry has revealed key differences in brain structure between people with and without anorexia nervosa.
Anorexia nervosa is an eating disorder defined by restriction of energy intake relative to requirements, leading to a significantly low body weight. Patients will have an intense fear of gaining weight and distorted body image and are unable to recognise the seriousness of their significantly low body weight.
Little is known about why some people develop anorexia whilst others do not, although biological factors are widely recognised. The findings from the study, which was coordinated by neuroscientists at the University of Bath with international partners, draws on extensive analyses of brain scans taken from patients around the world and goes some way to answering the question.
They reveal that people with anorexia demonstrate ‘sizeable reductions’ in three critical measures of the brain: cortical thickness, subcortical volumes and cortical surface area. Brain size reductions are significant due the implied loss of brain cells or the connections between them.
The results are some of the clearest yet to show links between structural changes in the brain and eating disorders. The team says that the effect sizes in their study for anorexia are in fact the largest of any psychiatric disorder investigated to date.
This means that people with anorexia showed reductions in brain size and shape two to four times greater than people with conditions such as depression, ADHD, or OCD. The changes observed in brain size for anorexia may be attributable to reductions in body mass index (BMI).
The team emphasised the importance of early treatment to help people with anorexia avoid long-term, structural brain changes. Existing treatment typically involves forms of cognitive behavioural therapy and, critically, weight gain. Many people with anorexia are successfully treated and these results show the positive impact such treatment has on brain structure.
Their study pooled nearly 2000 pre-existing brain scans for people with anorexia, including people in recovery and ‘healthy controls’ (people neither with anorexia nor in recovery). For people in recovery from anorexia, the study found that reductions in brain structure were less severe, suggesting that, with appropriate early treatment and support, brain self-repair is possible.
Lead researcher, Dr Esther Walton of the Department of Psychology at the University of Bath explained: “For this study, we worked intensively over several years with research teams across the world. Being able to combine thousands of brain scans from people with anorexia allowed us to study the brain changes that might characterise this disorder in much greater detail.
“We found that the large reductions in brain structure, which we observed in patients, were less noticeable in patients already on the path to recovery. This is a good sign, because it indicates that these changes might not be permanent. With the right treatment, the brain might be able to bounce back.”
“The international scale of this work is extraordinary,” said Paul Thompson, a professor of neurology and lead scientist for the ENIGMA Consortium, an international effort to understand the link between brain structure, function and mental health. “Scientists from 22 centres worldwide pooled their brain scans to create the most detailed picture to date of how anorexia affects the brain. The brain changes in anorexia were more severe than in other any psychiatric condition we have studied. Effects of treatments and interventions can now be evaluated, using these new brain maps as a reference.”
He added: “This study is novel in term of the thousands of brain scans analysed, revealing that anorexia affects the brain more profoundly than any other psychiatric condition. This really is a wake-up call, showing the need for early interventions for people with eating disorders.”
Source: University of Bath
