Youth aged 15-24 are likelier to have depression than all age groups in Canada. One-third of depressed youth do not respond to psychotherapy and/or antidepressant medications. A treatment called repetitive transcranial magnetic stimulation or rTMS has proven helpful in adolescents and young adults whose depressive symptoms have been difficult to treat with psychotherapy and/or antidepressants. Unfortunately, youth find rTMS difficult to access because it is not funded by the Ontario Health Insurance Plan, is typically only offered to adults, and the treatment schedule usually involves once-daily sessions, 5 days/week, for 4-6 weeks, which is associated with travel and opportunity costs e.g. missing school. This project looks at the feasibility of a new treatment pathway that allows youth with difficult-to-treat depression in hospital to receive rTMS twice-daily while engaging in on-unit schooling and therapeutic support. This "accelerated" way of providing rTMS is safe, has equal effectiveness to once-daily rTMS, and can shorten the time needed for treatment. This pathway is for youth already staying in hospital for difficult-to-treat depression or youth outside hospital who have difficult-to-treat depression that interferes with daily function to such a degree that they would benefit from staying in hospital. The investigators anticipate integrating rTMS and inpatient care for youth will be feasible, that it will be acceptable and accessible to youth and families, and there will be sufficient demand for this new treatment pathway. If successful, this project will inform care for youth with difficult-to-treat depression in Ontario and beyond.

Inclusion Criteria:

• age 14-19 years
• primary diagnosis of major depressive disorder or of bipolar I or II disorder, current episode depressed with no psychotic or mixed features
• current episode of depression lasting at least 4 weeks
• failed ≥1 evidence-based psychotherapy or antidepressant
• have a GRID-HAMD-17 (17-item Hamilton Depression Rating Scale) score of ≥16 (moderate-severe range)
• currently an inpatient or suitable for an elective inpatient admission

Exclusion Criteria:

• lifetime diagnosis of a psychotic disorder, anorexia nervosa, bulimia nervosa diagnosis of a substance use disorder (except caffeine and tobacco) within the past year
• obsessive compulsive disorder or personality disorder that is the main source and driver of distress
• active psychosis and/or mania
• history of epilepsy or any other neurologic condition that includes a history of seizures
• use of medications that lower the seizure threshold
• pregnancy or nursing
• history of severe headaches within the previous year
• improvement in depressive symptom severity between screening and baseline by 25% or more
• inability to adhere to the protocol