Anorexia Nervosa: Brain Connectivity Abnormalities

Functional magnetic resonance imaging is providing a new tool for understanding brain circuitry in normal brain development and in brain disorders. 

Anorexia nervosa is an restrictive calorie eating disorder often resistant to treatment.

No effective drug treatment for anorexia nervosa currently exists and psychotherapy is often only partially effective. A better understanding of the brain pathophysiology in anorexia nervosa is needed to aid in treatment development.

Stephanie Kullman along with colleagues at the University of Tubingen recently published a study of brain connectivity in twelve women with anorexia nervosa.

This study used a resting state functional connectivity approach with magnetic resonance imaging. In functional connectivity studies, the brain is studied during rest and levels of coherent activity between brain regions measured. 

The authors of this study noted anorexia nervosa commonly includes motor hyperactivity and so they used both a non-athlete and athlete female control group for comparision.

The primary findings from this study included the following:

• The brain inferior frontal gyrus (IFG) in both the left and right sides demonstrated reduced effective connectivity 
• Decreased effective connectivity was noted between the right IFG and the cingulate
• Increased effective connectivity was noted between the right IFG and the bilateral orbitofrontal gyrus region
• Increased effective connectivity was noted between the left IFG and the bilateral insular cortex

The authors note the inferior frontal cortex is a key region for executive functions, or control of complex cognitive functions. Disturbance of executive function in anorexia nervosa may contribute to food consumption and activity decision making.

The authors note their study found a link between level of physical hyperactivity in individual patients with anorexia nervosa and reduced IFG connectivity. Women with the highest level of physical activity had the lowest levels of IFG connectivity.

The areas of increased connectivity in this sample of patients with anorexia contribute to processing of the salience of stimuli. The authors note the insular cortex is a "multisensory neural node" involved in integration of "perception, emotion, interoceptive awareness, cognition and gustation". 

Disturbance of connectivity balance between the IFG and insular cortex may contribute to anxiety and fear related to somatic sensations.

The findings in this imaging study occurred in the context of active illness in anorexia nervosa. It would be interesting to follow these findings with recovery and weight restoration.

Additionally, modification of functional connectivity disturbances in anorexia may hold promise for new drug development and more effective psychological interventions.

Readers with more interest in this study can access the free full-text manuscript by clicking on the citation link below.

Image of brain with highlighted inferior frontal gyrus is from a screen shot from the Brain Tutor app for the iPad from the author's files.

Follow the author on Twitter @WRY999

Kullmann S, Giel KE, Teufel M, Thiel A, Zipfel S, & Preissl H (2014). Aberrant network integrity of the inferior frontal cortex in women with anorexia nervosa. NeuroImage. Clinical, 4, 615-22 PMID: 24936412