rTMS for Bulimia Nervosa does not exert additional benefit over placebo. Bulimia Nervosa is a disease strongly influenced by sociocultural influences and psychological factors. In the past this has led to preliminary optimism about efficacy of fluoxetine in this eating disorder. The efficacy was based on the trial effect (Hawthorne Effect). Being in a trial with appointments, rating sessions, diagnostic sessions has effect on well being especially in diseases with a strong origination in sociocultural and psychological factors.
Bulimia Nervosa is accompanied by several psychiatric disorders as co morbidity. Some believe that Bulimia Nervosa and Depression share a common aetiology, that they are both part of the affective spectrum disorder model.
The authors had hoped that high frequency rTMS modulated the feeding suppression area in the frontal lobe.
Fourteen women were randomized into two groups of outpatients of either active or placebo stimulation after a week of placebo wash-out. Stimulation was placed on the left dorsolateral prefrontal cortex. Stimulation was delivered for 3 weeks (3 x 5 days) with an intensity of 120% motor threshold using 20Hz, in one session a day.
There was a considerable improvement in binging and purging as well as depressive and obsessive-compulsive symptoms. However no significant difference between active and sham treatment.
The high placebo response is again established in this group comparable to the placebo response to selective serotonin reuptake inhibitors in this group. This effect could be due to increased awareness and the regular documentation of the binge behavior.
Presence of additional personality disorder interferes with outcome
Walpoth, M., Hoertnagl, C., Mangweth-Matzek, B., Kemmler, G., Hinterhölzl, J., Conca, A., Hausmann, A. (2008). Repetitive Transcranial Magnetic Stimulation in Bulimia Nervosa: Preliminary Results of a Single-Centre, Randomised, Double-Blind, Sham-Controlled Trial in Female Outpatients. Psychotherapy and Psychosomatics, 77(1), 57-60. DOI: 10.1159/000110061