The Effect of iTBS on the Inhibition Control Function of BN

Pathological out-of-control behavior is the core clinical symptom of Bulimia nervosa (BN). The study of its neural circuits and biological mechanism is very important to explore new intervention targets. Previous studies have found that the patients with BN have inhibitory control impairment, which may be the basis of uncontrolled binge eating and purging behaviors of BN. The study found that the cognitive decision-making dysfunction of substance addicts may lead to behavior solidification. At present, there is no related research on the cognitive decision-making model of BN. Previous studies of applicants have found that there is an enhancement in goal-oriented decision-making in BN, which may explain the binge eating and purging behaviors aimed at weight control. In addition, BN patients have obvious impulsiveness, and the individuals of BN often feel unable to control eating behavior , and experience obvious sense of out of control. The previous study confirmed that untreated BN patients were highly impulsive and had inhibitory control disorders. Inhibition and control disorder is one of the important pathogenesis of BN. Previous studies indicated that dorsolateral prefrontal cortex (DLPFC) and dorsomedial prefrontal cortex (DMPFC) were associated with aboved symptoms. In this study, the patients with BN were selected as subjects. A randomized, single-blind cohort study was designed to observe the effect of iTBS intervention of DLPFC or DMPFC on pathological out-of-control behavior. Combined with behavioral, neuroimaging and genetic techniques, the investigators focused on the function of the prefrontal lobe-striatum neural circuits dopamine system. By the objective markers of peripheral, brain imaging and behavior of BN, to provide new targets and ideas for the treatment of BN.

Bulimia nervosa(BN) is a chronic and refractory mental disorder characteristic of recurrent binge eating and weight control which mostly occur in adolescents and young women. The life-time prevalence ranges from 1.0%-4.2%, and keep increasing. Pathological out-of-control behavior is the core clinical symptom of BN. Impulsive personality trait is an important risk factor for overeating symptoms in patients with BN. Inhibition control dysfunction leads to increased impulsiveness, while impaired goal-oriented control leads to rigid behavior habits, such as obsessive-compulsive drug-seeking and drug use, resulting in pathological out-of-control behavior.

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive, safe and non-invasive physical intervention and nerve stimulation, which can be targeted at specific brain regions or networks, providing hope for people who do not respond well to drug therapy. iTBS stimulation mode can induce long-term potentiation of behavior and neural activity (LTP). Previous studies indicated that dorsolateral prefrontal cortex (DLPFC) and dorsomedial prefrontal cortex (DMPFC) were associated with out-of-control behavior.

In this study, the investigators will recruit 90 BN patients, would randomly divided into 30 DMPFC iTBS intervention group, 30 DLPFC iTBS and 30 sham-stimulation group. 20 iTBS will be given in the intervention group at DMPFC or DLPFC. To assess the eating disorder symptoms, impulsive and emotional change, clinical symptom scales, psychological scales and the behavioral experiments will be used at baseline, 4 weeks, 8 weeks, 12 weeks and16weeks, respectively. Furthermore, brain MRI will be used for BN at baseline.

This study is innovative and feasible. If the expected results can be obtained, it will lay a foundation for understanding the common mechanism behind the pathological behavior of BN and provide new directions and ideas for the design of effective intervention measures.

Eligibility Criteria:
Inclusion Criteria:

* female,
* Han nationality;
* right-handed;
* meet the diagnostic criteria of DSM-5 bulimia nervosa, body mass index (BMI) ≥ 18.5kg / m2;
* education level of junior high school or above, sufficient audiovisual level to complete the necessary examination of the study.
* Before entering the group, he has received fluoxetine treatment, the dose has been stable for one month, and has not received any form of physiotherapy (such as electroconvulsive therapy) within one month;
* each patient must understand the nature of this study and sign an informed consent form.

Exclusion Criteria:

* Patients who meet the diagnosis of DSM-5 other than BN, such as substance abuse / dependence, bipolar disorder, high risk of suicide, strong destructive impulses or antisocial behaviors;
* complicated with severe organic diseases and cognitive impairment, make it impossible for patients to complete the required symptom assessment and psychological tests;
* have a history of brain trauma or brain disease, epilepsy, etc. Those who have been exposed to ECT or MECT within 1 month;
* those with intracranial metal materials or pacemakers, implanted metal objects in vivo;
* those who are pregnant or planned pregnancy, women of childbearing age who are positive in pregnancy test.