NEUROMODULATION IN PSYCHOGERIATRICS: EMERGING EVIDENCE AND FUTURE DIRECTIONS.

Late-life mental illnesses, particularly treatment-resistant late-life depression, present a significant public health challenge due to complex interactions with medical comorbidity, polypharmacy, and neurocognitive disorders. Standard pharmacological treatments are often limited by efficacy and tolerability issues in this population. Neuromodulation has emerged as an essential therapeutic modality, offering targeted treatment that can circumvent systemic side effects. This narrative review provides a critical synthesis of the evidence for established neuromodulation techniques - Electroconvulsive Therapy (ECT), Repetitive Transcranial Magnetic Stimulation (rTMS), Transcranial Direct Current Stimulation (tDCS), and Vagus Nerve Stimulation (VNS) - and explores emerging approaches like Transcranial Focused Ultrasound (tFUS) within psychogeriatric populations. The application of these techniques is governed by a trade-off between efficacy, safety, and logistical burden. ECT remains the gold-standard for severe presentations, such as psychosis or catatonia, despite its cognitive risks. rTMS provides a powerful balance of efficacy and tolerability for non-psychotic TRD. tDCS and non-invasive VNS offer excellent safety profiles and potential for home-based administration, expanding access and showing promise for cognitive indications. While the clinical roles of these modalities are clarifying, the path forward requires addressing critical gaps. Future research must prioritize methodologically rigorous, geriatric-specific trials, the development of biomarkers to guide personalized treatment, and an unwavering focus on the ethical complexities of assessing capacity and obtaining informed consent. Integrating these imperatives will enable the field to deliver precise, effective, and patient-centered care for older adults.