Neuroimaging Biomarkers for Predicting rTMS Response in OCD

Medications (SSRIs and D2 antagonists) and cognitive-behavioral therapy are the mainstays of treating OCD; however, many patients show only a partial response, and more than 25% of patients show no improvement with these treatments. Repetitive transcranial magnetic stimulation (rTMS) is a promising alternative, using powerful, focused magnetic field pulses to stimulate target brain areas. So far, at least two stimulation targets have consistent evidence of efficacy in OCD: the dorsomedial prefrontal cortex (DMPFC) and the orbitofrontal cortex (OFC). Patients often show a strong response to one target but not the other. It is not well understood why some patients respond, while others do not. The investigators previously developed methods for discovering neurophysiological subtypes of depression based on resting state functional Magnetic Resonance Imaging (fMRI) measures of functional connectivity (RSFC) in relevant brain networks; diagnosing them in individual patients; and using them to predict individual differences in rTMS response. Subsequently, motivated by recent studies characterizing individual variability in the topology of these functional networks, the investigators have optimized methods for improving the accuracy of these predictions by accounting for individual variability, stabilizing the selection of treatment-predictive features, and increasing robustness in replication samples through regularization. Here, the investigators propose applying these methods to discover novel network-based subtypes of OCD and develop prognostic neuroimaging biomarkers for predicting differential treatment response to rTMS targeting the DMPFC or OFC, which could subsequently be tested in a randomized clinical trial.