Noninvasive Brain Stimulation as a Novel Treatment Approach for Anorexia Nervosa: A Meta-analysis and Systematic...

Pharmacological and psychological therapies are the main approaches for managing anorexia nervosa (AN). Recent advances in etiology and functional pathways in the brain have opened the gateway for assessing brain-focused treatment. Noninvasive techniques such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) have been researched for potential benefits. This systematic review and meta-analysis explored the effects of rTMS and tDCS on AN with respect to eating behavior, body mass index (BMI), and comorbid symptoms.

Electronic database searches were conducted based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using the following keywords: eating disorders, anorexia nervosa, neurostimulation, repetitive transcranial magnetic stimulation, rTMS, and transcranial direct current stimulation, tDCS. The study included articles published in English until December 2024. The data extracted from the studies included author details, year of publication, type of study design, type of stimulation, stimulation methods, sessions, outcomes, and comorbid symptoms. A total of 20 studies were included in the review; 16 used rTMS, and four used tDCS. Five studies were included in the meta-analysis. The dorsolateral prefrontal cortex (DlPFC) was the main target area for neurostimulation. One study targeted the bilateral dorsomedial prefrontal cortex, right inferior parietal lobe, and insula. The meta-analysis revealed increased BMI following rTMS (standardized mean difference [SMD] = 0.174, 95% confidence interval [CI]: -0.201 to 0.548, p = .363). The Eating Disorder Examination Questionnaire score decreased (SMD = 0.231, 95% CI: -0.204 to 0.671, p = .304), and there was a significant reduction in comorbid depression (SMD = -0.501, 95% CI: -0.941 to -0.053, p = .030) and anxiety (SMD = -0.461, 95% CI: -0.892 to -0.025, p = .040). Studies involving tDCS showed potential improvement in BMI, core symptoms of AN, and its associated symptoms.

Noninvasive neurostimulation has shown improvement in the symptoms of AN and BMI, although meta-analyses have not yet demonstrated robust effects. In contrast, more substantial evidence supports its efficacy in alleviating mood symptoms. Further research is needed to understand the underlying mechanisms, optimize targets, and refine stimulation parameters, which are crucial for developing effective brain-targeted interventions.