The purpose of this study is to see how well a treatment called "Repetitive Transcranial Magnetic Stimulation" works for patients who struggle with symptoms of both posttraumatic stress disorder and major depressive disorder.

This study aims to evaluate the safety and efficacy of repetitive transcranial magnetic stimulation (rTMS) for adults with comorbid posttraumatic stress disorder (PTSD) and major depressive disorder (MDD). Although standard rTMS uses stimulations delivered to the left prefrontal cortex at 10 pulses per second, prior work has shown that other stimulation frequencies may work for both PTSD and MDD. In this study, we examine the efficacy of left-sided 5Hz in patients with PTSD and MDD, hypothesizing that this lower frequency will improve PTSD and MDD symptoms.

Inclusion Criteria:

1. To ensure subjects can safely receive rTMS, eligible subjects must meet all established screening criteria for safety during MRI (magnetic resonance imaging), since MRI involves magnetic fields at similar intensity to those emitted from the rTMS treatment coil. These are conservative measures require a patient not having the following (unless MRI-safe): Cardiac pacemaker, implanted device (deep brain stimulation) or metal in the brain, cervical spinal cord, or upper thoracic spinal cord;
2. Outpatients 18-70 years of age (inclusive)
3. Meet DSM-IV criteria for MDD (recurrent or single episode chronic) and PTSD (acute or chronic) at the time of the screening and baseline visits;
4. Have a baseline score of "Moderately Ill" or worse on both the CGI-S and the PGI-S.
5. Have failed at least one antidepressant medication trial as part of definitive and adequate treatment in the current episode, OR have demonstrated intolerance to at least one antidepressant medication as part of attempted treatment in the current episode of illness (i.e., meet FDA labeling requirements for administration of rTMS for depression);
6. Be on a stable psychotropic regimen for at least six weeks (42 days) prior to screening, or no psychotropic medication at all, and be willing to maintain the current regimen and dosing for the duration of the study (unless medical necessary to make changes with notification of research staff);
7. If female and of child bearing potential, agree to use an acceptable method of birth control for the duration of the study treatment period
8. Be willing and able to comply with all study related procedures and visits,
9. Be capable of independently reading and understanding patient information materials and giving written informed consent.

Exclusion Criteria:

1. Are pregnant or lactating or planning to become pregnant within the next three months.
2. Have a lifetime history of loss of consciousness due to head injury for greater than 10 minutes, or any lifetime history of loss of consciousness due to a head injury with documented evidence of brain injury (including brain atrophy).
3. Current (or past if appropriate) significant neurological disorder, or lifetime history of a) seizure disorder b) primary or secondary CNS tumors c) stroke or d) cerebral aneurysm;
4. Current Axis 1 primary psychotic disorder, or bipolar I disorder, current alcohol and/or substance dependence or abuse within the past 1 month;
5. Past treatment with TMS therapy
6. Have active suicidal intent or plan as detected on screening assessments, or in the Investigator's opinion, is likely to attempt suicide within the next six months.
7. Demonstrate the presence of any other condition or circumstance that, in the opinion of the investigator, has the potential to prevent study completion and/or to have a confounding effect on outcome assessments.

Comorbid PTSD & MDD

baseline to endpoint (week 10 or LOCF).

Adverse event data collected through (1) Response of participants to queries by study clinicians during treatment sessions and during study-specific assessment visits (2) spontaneous reports initiated by participants.