• are inpatients or outpatients;

• demonstrate capacity to consent according to the MacArthur competence assessment tool for clinical research (MacCAT-CR);

• 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);

• are 18 years of age or older;

• have demonstrated resistance to at least 2 antipsychotics of 600 mg of chlorpromazine equivalents for at least 6 weeks;

• 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;

• are considered to be appropriate to receive convulsive therapy as assessed by an ECT attending psychiatrist and a consultant anaesthesiologist;

• 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;

• are able to adhere to the intervention schedule;

⁃ meet the MST safety criteria;

⁃ If a woman of child-bearing potential: is willing to provide a negative pregnancy test and agrees not to become pregnant during trial participation.