Cognitive Biomarkers in Eating Disorders

I previously posted on a review of the neuropsychological domain of set-shifting as a possible biomarker for eating disorders.  In that post, set shifting as measured by the Wisconsin Card Sort tests was impaired in those with an anorexia nervosa and continued impaired despite weight restoration.  Additionally, sisters of those with an eating disorder, also showed some impairment on this measure even when they had no eating disorder problem.  This supports a potential role for set shifting as a potential biomarker for eating disorders.

Now an additional study of neuropsychological performance in women with eating disorders and their healthy sisters has been published in the journal Comprehensive Psychiatry.  In this study, the authors examine two computerized tasks tapping the symmetry of performance of the brain’s left and right hemisphere.   

The test of right hemisphere function involved a two-bar visual bar graph stimulus.   Participants were asked to identify the presentation as odd or even dependent on the location of an indicator arrow.  In the test of left hemispheric function task, four letter strings were presented and participants were asked to identify the words as real work or a pseudoword.

The subjects with eating disorders included young women with anorexia nervosa, restricting subtype, anorexia nervosa, binge-purge subtype and bulimia nervosa.  The neuropsychological tests were assessed for accuracy and speed of response.  The key finding from the study were:

• Patients with eating disorders showed higher error rates and slower response times on tests of both the right and left hemisphere
• Anorexia nervosa, restricting subtype tended to be associated with the greatest level of impaired functioning
• Sisters of the eating disorder subjects also showed impairment despite scores similar to controls on measures of depression, impulse control, obsessional thinking and eating disorder symptoms

The authors note that there results support “general individual differences in cognitive processes that may run in families, irrespective of the eating disorder condition of the family member”.    The authors also note that their findings support the continuum model of eating disorders proposed by Michael Strober.  This model proposes that anorexia nervosa, restricting subtype is the most severe category of the eating disorders with bulimia nervosa being the least severe (on a general basis, it is possible for some individuals with bulimia nervosa to have a more severe eating disorder than some individuals with anorexia nervosa, restricting subtype).   The data from this study indicate the anorexia nervosa restricting subtype demonstrated the most severe neurocognitive impairment with bulimia nervosa the least impairment.

Look for more studies examining neurocognitive function in those with eating disorders.  Strategies that combine neuropsychological assessment with fMRI and genetic data may be the most powerful strategy for research in these disorders.  


Photo of rescued sea turtle from the Loggerhead Marine Center in Juno Beach, Florida courtesy of Yates photography

Rozenstein MH, Latzer Y, Stein D, & Eviatar Z (2011). Neuropsychological psychopathology measures in women with eating disorders, their healthy sisters, and nonrelated healthy controls. Comprehensive psychiatry PMID: 21397219