Theta Burst Stimulation in Anorexia Nervosa

Anorexia Nervosa (AN) is a life-threatening eating disorder characterised by an intense fear of weight gain and disturbed body image, which motivates severe dietary restriction or other weight loss behaviours (e.g. purging). Treatment efficacy in adults with AN remains low: only a small percentage of individuals fully recover, and dropout rates are high. For adolescents with a relatively short term illness duration (under 3 years), family-based therapy has been associated with more favourable outcomes. However, for those adolescents with a longer illness duration (over 3 years), there are no specific treatments associated with positive long-term outcomes and these individuals are at risk of developing a severe and enduring form of the illness (SE-AN). In part, treatment can be problematic due to ambivalence, which is reflected in poor take-up of certain treatments (e.g. pharmacological treatments that lead to weight gain) and high drop-out rates. Repetitive transcranial magnetic stimulation (rTMS) has demonstrated efficacy for treatment of AN in adults and improving treatment adherence. However, this has yet to be investigated in adolescents with AN. This study will use a novel type of rTMS, theta burst stimulation (TBS), including intermittent TBS (iTBS) and continuous TBS (cTBS). TBS takes as little as a few minutes duration compared to the classical rTMS protocol which takes approximately 37.5 minutes. In addition, TBS has been found to produce longer after-effects of the induced plastic changes and has a lower stimulation intensity, which may therefore be more practical and potentially safer to administer in people with AN. Thus, the aim of this proof-of-concept trial is to obtain preliminary data on the safety and short-term (i.e. up to 24 hours) effects of a single session of iTBS and cTBS, compared to sham TBS, on reducing core symptoms of AN.