In this study, the investigators will be examining the effects of repetitive transcranial magnetic stimulation (rTMS) on memory deficits in individuals with schizophrenia and schizoaffective disorder. Half of the study participants will be chosen by chance to receive active rTMS stimulation while half will be chosen by chance to receive sham rTMS. Sham rTMS will feel the same as active rTMS only there will be no direct brain stimulation. This is necessary to ensure that active rTMS is efficacious in the enhancement of memory in individuals with schizophrenia. Based on results from a recently published pilot study, the investigators propose that active rTMS treatment will result in a significant improvement in working memory performance compared to sham rTMS treatment.

This study is a randomized, double blind, sham controlled study to evaluate the efficacy of repetitive transcranial magnetic stimulation as a treatment for working memory deficits in individuals with schizophrenia or schizoaffective disorder between 18 and 59 years of age. The study duration is approximately 3 months, with the rTMS sessions lasting for 4 weeks, 5 times a week, for about 1 hour each. Several scales will be used to assess symptom severity as part of the clinical assessment. Cognition will be assessed using a validated battery and the N-back task.

This study also involves a type of brain imaging known as magnetic resonance imaging (MRI) at the beginning and at the end of the 4 weeks of daily rTMS to better understand the effects of rTMS on brain structure and function. Investigators will measure the size and connections of different parts of the brain to assess brain structure and blood flow while you are completing some basic tasks to assess brain function. We will also collect two blood samples (before and after rTMS treatment) to see if certain proteins change in response to treatment. Finally, an analysis of genetic material will be conducted to see if genes play a role in differences in how people respond to treatment.

Inclusion Criteria:

• Between 18 and 59 years of age
• Current diagnosis of Schizophrenia or Schizoaffective Disorder
• Able to provide written informed consent
• Fluency in the English Language

Exclusion Criteria:

• Have a history of substance abuse or dependence in the last 6 months
• Have a concomitant major and unstable medical or neurologic illness
• Have a history of seizures or have a first degree relative with a history of a seizure disorder
• Current pregnancy or a plan to become pregnant during the duration of the study
• Clinical instability: determined by treating physician
• Have received electroconvulsive therapy (ECT) within the last year
• Have a history of repetitive transcranial magnetic stimulation (rTMS)
• Are taking a benzodiazepine at a dose greater than Lorazepam 2mg or equivalent
• Are taking any non-benzodiazepine anticonvulsant
• Have a cardiac pacemaker, cochlear implant, implanted electronic device or non-electric metallic implant