675. Beyond the cortex: expanding non invasive brain stimulation for psychiatry

Abstract

Abstract Background Non-invasive brain stimulation (NIBS) has emerged as a valuable therapeutic approach in psychiatry, offering an alternative to conventional pharmacological treatments. Evidence indicates that NIBS can be highly effective in certain conditions; for instance, repetitive transcranial magnetic stimulation (rTMS) has demonstrated outcomes comparable to, and in some cases surpassing, pharmacotherapy in treatment-resistant depression. Nevertheless, while established modalities such as transcranial electrical stimulation (tES) and TMS provide meaningful clinical benefits, their effects are largely confined to superficial cortical regions. This limitation is significant, as many of the core neural circuits implicated in psychiatric disorders reside within deeper brain structures that remain beyond the direct reach of these techniques. Aims & Objectives In this talk, Prof. Georg Kranz will provide an overview of current evidence supporting the application of NIBS in psychiatry. He will then address the limitations of established techniques, particularly their restricted ability to modulate deeper brain structures that are central to many psychiatric disorders. Finally, the talk will highlight the need for further clinical research into innovative approaches, including transcranial interferential stimulation (TIS), transcranial ultrasound stimulation (TUS), and its pulsed variant, transcranial pulse stimulation (TPS). Method The talk will draw on a diverse body of research, spanning clinical case studies and correlational investigations incorporating neuroimaging, as well as comprehensive systematic reviews and meta-analyses. Results rTMS has emerged as a leading non-invasive intervention in psychiatry, particularly for treatment-resistant depression. Recent meta-analyses and large clinical trials consistently demonstrate that rTMS yields higher remission and response rates than pharmacotherapy alone, while producing fewer systemic side effects. In addition, growing evidence in schizophrenia suggests that rTMS can alleviate symptoms such as auditory hallucinations, though findings remain heterogeneous. Although somewhat less robust than rTMS, tES also shows promise as an adjunctive treatment. Clinical trials in major depressive disorder report modest improvements in both cognition and mood, with home-based tDCS protocols proving feasible and safe under remote supervision. Research in depression and bipolar disorder further highlights its portability and potential to enhance quality of life, though therapeutic effects are generally moderate and vary across individuals. Discussion & Conclusions rTMS and tES are powerful techniques for modulating surface-level cortical networks; however, their inability to directly access deeper brain structures remains a critical limitation in addressing psychiatric conditions rooted in limbic and subcortical dysfunction. To overcome this depth constraint, innovative approaches such as TIS, TUS and TPS are being explored, offering the potential to target and modulate these clinically relevant circuits with greater precision.