Grant: Master's Award: Canada Graduate Scholarships

Major Depressive Disorder (MDD) is estimated to affect nearly 3 million individuals in Canada within a given year. Of these, an approximate 30% are classified as having Treatment-Resistant Depression (TRD) and do not remit from medications and psychotherapy – suggesting that there is much to understand regarding depression’s persistence and treatment. Current diagnostic standards result in a clinical umbrella (“depression”) to encompass over 227 possible permutations of symptoms, with treatments being similarly uniform in their approach. The neglect of inter-individual heterogeneity may underly the variability of treatment response. An alternative model, network science, proposes that disorders are not caused by an underlying, latent disease (e.g., “MDD”) – but that symptoms tend to cluster and cause each other in the manifestation of a disorder. Dynamic time warping (DTW) is a statistical method that analyzes how these symptom-level interactions change over time, and in what order. DTW has never been done with transcranial magnetic stimulation (rTMS), which is a safe and efficacious method for treating TRD. The proposed exploratory study will use DTW to model symptom-level heterogeneity in treatment response among patients undergoing rTMS for TRD. rTMS will be conducted according to clinical standards (once a weekday, for 6 weeks). The HRSD-17 will be used to assess MDD symptoms at baseline and after each week of treatment. This data will be analyzed using DTW, resulting in a visual model of symptom change patterns over rTMS. This study may indicate MDD phenotypes that are best targeted with rTMS. With efficacious and individualized medicine, emerging treatments may better relieve the burden of illness off those affected by MDD and the broader institutions they occupy.