Inside the Eating-Disordered Mind
Why are eating disorders are associated with cognitive impairment?
Posted Jun 05, 2014
This is a guest post by Emily Shea, Williams College Class of 2016.
Eating disorders are very prevalent both in the United States and worldwide. Though males can be and are affected, the disorders predominate in women, with staggering statistics. It is predicted that 0.5 to 3.7 percent of women suffer from anorexia nervosa at some point in their lives, with a 1.1 to 4.2 percent lifetime prevalence of bulimia nervosa on top of that statistic (National Association of Anorexia Nervosa and Associated Disorders). Eating disorders were reported to be the third most common illness classified as “chronic” for adolescents in 2000.
Recent studies have linked eating disorders to impaired cognitive functioning. Evidence points to problems with visuo-spatial reasoning and motor function. More important, the functioning of the central executive seems to be impaired in eating disordered patients (Weider et. al. 2014). The central executive is a critical component of the mind. It is, in a sense, the conductor, or boss, that coordinates thinking. Executive functions include the initiation of decision making, allocating attention, and planning out tasks.
Eating disorder patients often have persistent, obsessive thoughts about food, hunger, exercise, body shape and the like. It is possible that these thoughts “use up” some of their cognitive resources most of the time, leaving less ability to plan other decisions and perform other tasks. It is also possible that malnourishment also decreases their cognitive resources.
Let’s call this Theory 1: The link between eating disorders and decreased cognitive function comes from decreased cognitive resources caused by constant malnourishment and obsessive thinking about food, hunger, etc. If theory 1 is true, then cognitive function should return to normal levels if someone who had an eating disorder gets mentally and physically healthy.
Another possibility, call it Theory 2, is that diminished cognitive function is permanent and will not increase to normal levels even if someone gets mentally and physically healthy. This permanent impairment could be a pre-existing state or it could be caused by permanent damage as a result of malnourishment.
To distinguish between Theory 1 and Theory 2, Weider et al, (2014) tested patients and controls using a composite executive function score from such tasks as categorizing objects, sorting cards, inhibiting reading to identify colors and planning out the building of a tower. Anorexic patients performed about 1.5 standard deviations below healthy controls, whereas bulimics still performed below the healthy, at approximately 0.5 standard deviations below the mean control score. However, after adjusting for such factors as body mass index and depression score, which may be indicative of the patients current state of disorder, only a small improvement was made in approaching the healthy mean. Therefore, it seems that the current state of malnourishment cannot be the whole story.
Additional studies support this conclusion. A longitudinal study of executive function in eating disorders, conducted by Gillberg et al. (2010), tested subjects during adolescence, when they were afflicted by the disorder, and eighteen years later, when 84 percent of participants were found to be completely recovered. People who had suffered from an eating disorder performed more poorly than controls on this test 18 years later, even though these participants were now well-nourished and lacking a clinical diagnosis. Furthermore, in viewing the brain with MRI and fMRI to understand its structure and activity, eating disorder patients’ brains revealed various abnormalities including altered blood flow to the temporal lobes, decreased grey matter, and more. Some problems improved after the patient regained weight, indicating a malnourishment component, but some did not (Lena, 2004).
Together, these results support Theory 2. People with eating disorders did not fully recover even after they were healthy.
Debate continues about why. It is possible that being malnourished damaged the brains of people with eating disorders. Alternatively, these deficits in abilities might have been present before the onset of the disorder. It is difficult to distinguish between pre-existing differences and effects of brain damage. Given the prevalence of eating disorders, continued exploration of this question is critical.
One thing is clear: People with eating disorders often have mild cognitive impairments. These impairments can have far-reaching consequences (including increased likelihood of relapse following treatment; Duchesne et al., 2004). And they do not necessarily go away when these patients get healthy. Acknowledging these impairments can promote better understanding of the victims of eating disorders, and hopefully result in better treatment and recovery for all involved.
Duchesne, M., Mattos, P., Fontenelle, L., Veiga, H., Rizo, L., and Appolinario, J. (2004). Neuropsychology of eating disorders: a systematic review of the literature. In Brazilian Journal of Psychiatry. (Vol. 26, No. 2). Sao Paulo, Brazil.
Gillberg, I.C., Billstedt, E., Wentz, E., Anckarsater, H., Rastam, M., & Gillberg, C. (2010). Attention, executive functions, and mentalizing in anorexia nervosa eighteen years after onset of eating disorder. In Journal of Clinical and Experimental Neuropsychology (Vol. 32, Issue 4).
Lena, S.M., Fiocco, A.J., & Leyenaar, J.K. (2004). The role of cognitive deficits in the development of eating disorders. In Neuropsychology Review (In Vol 14, Issue 2, pp 99-113).
National Association of Anorexia Nervosa and Associated Disorders. “Eating Disorder Statistics.” Accessed 21 April 2014. <http://www.anad.org/get-information/about-eating-disorders/eating-disord...
Weider, S., Indredavvik, M.S., Lydersen, S., & Hestad, K. (2014). Neuropsychological function in patients with anorexia nervosa or bulimia nervosa. International Journal of Eating Disorders: E-pub.