In this study, the investigators will be examining the effects of the deep repetitive transcranial magnetic stimulation (rTMS) using the H1 coil in patients over the age of 60 diagnosed with mild to early-moderate Alzheimer's disease (AD) or mild cognitive impairment (MCI) and comorbid Major Depressive Disorder (MDD) who have been unable to tolerate or failed to respond to antidepressant medications. The coil was designed to stimulate deeper regions of the left dorsolateral prefrontal cortex (DLPFC). Based on prior research, the investigators propose that active stimulation with the H1 coil for 4 weeks may result in significant remission rates and will be tolerable and safe.

This study is an open-label trial to evaluate the safety and efficacy of H1-coil dTMS in treating depression in MCI and mild AD patients over 60 years of age who have not tolerated or failed to respond to antidepressant medications. 28 patients will be assigned to receive 4 consecutive weeks of daily active dTMS treatment. The long-term effects of treatment on emotional cognitive measures will be assessed at a 4-week follow-up visit (8 weeks from baseline). Symptom change and remission criteria will be assessed using the Montogmery-Asberg Depression Rating Scale (MADRS). Cognition will be assessed using a validated neuropsychological battery.

We will also offer patients to receive 4 weeks of treatment using theta-burst TMS, which is a milder version of TMS.

Inclusion Criteria:

• meet DSM 5 criteria for Major or Mild Neurocognitive Disorder due to Alzheimer's disease with Clinical Dementia Rating Scale (CDR) score of at least 0.5
• have been diagnosed with DSM5 Major Depressive Disorder, with the current episode longer than 4 weeks but less than 5 years
• did not respond to or did not tolerate antidepressant treatment
• are willing to provide informed consent
• are able to follow the treatment schedule
• are stable on medications for 2 months and are not expected to change medication during the entire study period (if they are taking medications)
• have a satisfactory safety screening questionnaire for TMS
• have an informant/study partner who is able to complete study questionnaires regarding the participant

Exclusion Criteria:

• have a metal plate in their head, except in the mouth (such as an ear implant, implanted brain stimulators, aneurysm clips)
• have known increased pressure or a history of increased pressure in their brain, which may increase their risk for having seizures
• have a cardiac pacemaker
• have an implanted medication pump
• have a central venous line
• have a significant heart disease or history of stroke
• Modified Hachinski Score (MHIS) > 3 (to exclude those with significant vascular component to memory loss)
• have a history of any psychotic disorder, bipolar disorder, eating disorder, obsessive compulsive disorder, post-traumatic stress disorder, or dementia other than AD
• have a history of substance abuse in the last 6 months
• have a history of stroke or other brain lesions
• have a personal history of epilepsy
• have a family history of epilepsy
• are a pregnant or breast-feeding woman
• are taking psychotropic medications including antidepressant medications, antipsychotics or mood stabilizing medications due to increased risk of seizure
• are taking memantine
• have a history of abnormal MRI of the brain
• have significant hearing loss requiring use of hearing aids
• have untreated hypo- or hyper-thyroidism