Investigating Treatment Response in Obsessive–Compulsive Disorder Through Neuromodulation and Patient-Derived Induced Pluripotent Stem Cell Models: Preliminary Clinical Observations from a Translational Study

Background: Treatment-resistant obsessive–compulsive disorder (OCD) is a heterogeneous and clinically challenging condition. Growing evidence suggests alterations in glutamatergic signaling within cortico–striatal–thalamo–cortical circuits, including those involving medium spiny neurons (MSNs), as well as genetic factors affecting synaptic organization, although the biological mechanisms underlying differential treatment response remain incompletely understood. Methods: This multicenter study presents a translational research framework aimed at investigating potential molecular and cellular correlates of treatment response in a cohort of patients with OCD, stratified according to their response to pharmacological treatments and transcranial magnetic stimulation (TMS). Peripheral blood mononuclear cells from clinically defined subgroups are reprogrammed into human induced pluripotent stem cells and differentiated into MSN-enriched neuronal cultures, enabling in vitro investigation of morphological, biochemical, and transcriptomic features associated with different clinical profiles. Optogenetic and pharmacological stimulation paradigms are applied to probe selected aspects of neuronal activation in vitro, providing a controlled and simplified experimental framework to explore cellular responses under different treatment conditions. By integrating clinical phenotyping with patient-derived cellular models, this study establishes a translational platform for hypothesis generation in the investigation of treatment response in OCD. Results and Conclusions: Preliminary clinical observations from an initial cohort undergoing neuromodulation are also reported to document feasibility and early clinical implementation of the study, providing an initial characterization of the cohort.