This trial aims to assess the clinical effects and tolerability of Magnetic Seizure Therapy (MST) as an alternative to electroconvulsive therapy (ECT) for Treatment Resistant Schizophrenia (RS).

The study will involve a randomized, double blind, non-inferiority clinical trial with two treatment arms conducted in two academic institutions (the Centre for Addiction and Mental Health (CAMH) in Toronto, and University of British Columbia (UBC) Hospital in Vancouver, British Columbia). The investigators will compare MST to right unilateral ultrabrief pulse ECT (RUL-UB-ECT). Treatment will be administered two to three days per week. Clinical response will be assessed with the 18-item Brief Psychiatric Rating Scale (BPRS). Response will be defined as greater than or equal to 40% decrease in the BPRS positive psychotic symptom subscale (4 items - hallucinatory, behavior, suspiciousness, conceptual disorganization, and unusual thought content). Patients who do not meet response criteria after 15 treatment sessions will be considered non-responders and will cease treatment sessions. The blind will not be broken to participants until the completion of the entire study.

Inclusion Criteria:

1. are inpatients or outpatients;
2. demonstrate capacity to consent according to the MacArthur competence assessment tool for clinical research (MacCAT-CR);
3. have a DSM-5 diagnosis of Schizophrenia or Schizoaffective Disorder for at least 2 years, as determined by the MINI International Neuropsychiatric Interview - Version 7 (MINI-7.0);
4. are 18 years of age or older;
5. have demonstrated resistance to at least 2 antipsychotics of 600 mg of chlorpromazine equivalents for at least 6 weeks;
6. have a BPRS score at baseline of at least moderate severity (>4) on one of the four psychotic items (i.e., hallucinatory behavior, suspiciousness, conceptual disorganization, unusual thought content) or at least 12 on these 4 items combined;
7. are considered to be appropriate to receive convulsive therapy as assessed by an ECT attending psychiatrist and a consultant anaesthesiologist;
8. are on an antipsychotic at an adequate dose and are agreeable to keeping their current antipsychotic treatment constant during the acute phase of the intervention;
9. are able to adhere to the intervention schedule;
10. meet the MST safety criteria;
11. If a woman of child-bearing potential: is willing to provide a negative pregnancy test and agrees not to become pregnant during trial participation.

Exclusion Criteria:

1. have a history of MINI diagnosis of a substance use disorder (other than nicotine and caffeine) within the past three months;
2. have a concomitant major unstable medical illness;
3. are pregnant or intend to get pregnant during the study;
4. have probable dementia based on study investigator assessment;
5. have any significant neurological disorder or condition likely to be associated with increased intracranial pressure or a space occupying brain lesion, e.g., cerebral aneurysm;
6. present with a serious medical condition,
7. have an intracranial implant (e.g., aneurysm clips, shunts, stimulators, cochlear implants, or electrodes) or any other metal object within or near the head, excluding the mouth, that cannot be safely removed;
8. require a benzodiazepine with a dose > lorazepam 2 mg/day or equivalent or any anticonvulsant due to the potential of these medications to limit the efficacy of both MST and ECT;
9. are unable to communicate in English fluently enough to complete the neuropsychological tests;
10. have a non-correctable clinically significant sensory impairment (i.e., cannot hear or see well enough to complete the neuropsychological tests).

De-identified data from this project will be used for future research by internal and external project collaborators. Deidentified participant data along with data dictionaries will be made available and to gain access data requestors will need to sign a data access agreement.

Beginning 12 months and ending 3 years after publication of the primary outcome paper.

Participants will be randomized into the study using a permuted block method with a random number generator. The study statistician will prepare the randomization scheme. The block size will be fixed and study personnel will be blinded to the randomization block size.