Study Protocol: Using Deep-Brain Stimulation, Multimodal Neuroimaging and Neuroethics to Understand and Treat Severe Enduring Anorexia Nervosa.

backgroundResearch suggests that altered eating and the pursuit of thinness in anorexia nervosa (AN) are, in part, a consequence of aberrant reward circuitry. The neural circuits involved in reward processing and compulsivity overlap significantly, and this has been suggested as a transdiagnostic factor underpinning obsessive compulsive disorder, addictions and eating disorders. The nucleus accumbens (NAcc) is central to both reward processing and compulsivity. In previous studies, deep-brain stimulation (DBS) to the NAcc has been shown to result in neural and symptomatic improvement in both obsessive compulsive disorder and addictions. Moreover, in rats, DBS to the NAcc medial shell increases food intake. We hypothesise that this treatment may be of benefit in severe and enduring anorexia nervosa (SE-AN), but first, feasibility and ethical standards need to be established. The aims of this study are as follows: (1) to provide feasibility and preliminary efficacy data on DBS to the NAcc as a treatment for SE-AN; (2) to assess any subsequent neural changes and (3) to develop a neuroethical gold standard to guide applications of this treatment.

methodThis is a longitudinal study of six individuals with SE-AN of >7 years. It includes an integrated neuroethical sub-study. DBS will be applied to the NAcc and we will track the mechanisms underpinning AN using magnetoelectroencephalography, neuropsychological and behavioural measures. Serial measures will be taken on each intensively studied patient, pre- and post-DBS system insertion. This will allow elucidation of the processes involved in symptomatic change over a 15-month period, which includes a double-blind crossover phase of stimulator on/off. DISCUSSION: Novel, empirical treatments for SE-AN are urgently required due to high morbidity and mortality costs. If feasible and effective, DBS to the NAcc could be game-changing in the management of this condition. A neuroethical gold standard is crucial to optimally underpin such treatment development. CLINICAL

trial registrationThe study is ongoing and registered with www.ClinicalTrials.gov, https://clinicaltrials.gov/ct2/show/NCT01924598, 22 July, 2013. It has full ethical and HRA approval (Project ID 128658).