Assessing the efficacy and safety of rTMS, tDCS, and DBS in treating auditory hallucinations: a scoping review

Auditory hallucinations (AH)-the perception of sound in the absence of any external auditory stimulus-are among the most clinically significant and personally distressing symptoms encountered in psychiatry and neurology. Although AH is canonically associated with schizophrenia spectrum disorders, where it affects 60-80% of patients at some point in the illness course, it also emerges in major depressive disorder with psychotic features, bipolar disorder, post-traumatic stress disorder, borderline personality disorder, substance-induced psychoses, and a range of neurological conditions including epilepsy, Parkinson's disease, Lewy-body dementia, and acquired brain injury. Patients with treatment-resistant AH (TR-AH) experience a substantial decline in their quality of life and face increased economic burden. The limitations of existing pharmaceutical treatments have spurred researchers to develop and assess neuroregulation techniques that can directly target abnormal neural circuits involved in the pathophysiology of AH. This review consolidates the current research findings of stimulation-based treatment methods for AH and aims to conduct an evidence-based evaluation of efficacy, safety, and practical feasibility of three neuromodulation methods: repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), and deep brain stimulation (DBS). By making a comparison of these three methods, this review presents their respective risks and strengths and offers implications for future research direction.