Anorexia patients found to have enhanced senses of smell

Young women suffering from anorexia nervosa, an eating disorder that causes them to lose more weight than is deemed healthy for someone of their height and age, could develop an enhanced sense of smell, according to research published earlier this year in the journal PLOS One.

People with anorexia have a distorted image of their own body, an intense fear of gaining weight and extremely low body weight, according to the National Institutes of Health (NIH). They often diet or exercise too much, or go to even more extreme measures in an attempt to lose weight.

Now, researchers from the University of Copenhagen Department of Clinical Medicine and the Mental Health Services in the Capital Region of Denmark have discovered that they also tended to be highly sensitive to smells, and that this olfactory sensitivity could play an important role in the disorder, according to a report published this weekend by the website PsyPost.

“The interest in olfaction and anorexia nervosa began with the intention to understand why it is so difficult to recover from this disorder in some, but not all, cases,” study author Mette Bentz told PsyPost via email. “My colleagues and I decided to study social functioning in persons with anorexia nervosa, along with areas that might relate to social functioning.”

“The sense of smell is associated with social functioning in other psychiatric disorders, and therefore, olfaction might be a simpler way to measure individual differences in persons with anorexia nervosa, which might predict functioning in social domains,” the researcher added.

Discovery could lead to new treatment options

The sense of smell has a significant influence on the eating process in healthy individuals, Bentz told PsyPost, and since the consumption of food is a key component of anorexia, the study author reasoned that altered olfactory processing could be a factor in the eating disorder as well.

“We knew from the research of others that olfaction shares some brain networks with executive functions, such as mental flexibility,” she explained. “Mental flexibility is in turn reduced in adults with anorexia nervosa and might explain why it is so difficult to change cognitive and behavioral patterns of anorexia nervosa, once they are firmly in place.”

As part of their research, Bentz and her colleagues looked at 43 young women with first-episode anorexia, 27 recovered anorexia patients and 39 females with no history of the condition. Each of the participants were between 14 and 22 years of age, PsyPost said, and each took part in an odor threshold test, an odor identification test and an eating disorder evaluation, the authors added.

Both of the clinical groups were found to have heightened olfactory sensitivity when compared to the control group, the study authors reported. Furthermore, once patients who had also been diagnosed with depression were excluded, participants with first-episode anorexia were found to be better at identified odors than those who had recovered from the condition.

“The superior olfaction in those who had anorexia nervosa or were recovered from anorexia nervosa was not related to their cognitive or social functioning,” Bentz explained. This could be “related to anxiety in general concerning bodily senses, or anxiety specifically concerning food related stimuli,” she added. “Therefore we speculate that superior olfaction might be involved in exacerbating disordered eating in anorexia nervosa.”

While the study only looked at female patients, if the results were correct, it could lead to a new method of treatment for anorexia patients, the researchers said. Specifically, if doctors can help their recovering patients avoid strong smells, it could make the process of renourishing them far easier, and gradually getting patients used to strong smells could help them overcome their fear of eating, the lead author told PsyPost.


Image credit: Unsplash/Melanie Wasser