Effect of Repetitive Transcranial Magnetic Stimulation on Language in Alzheimer's Disease

The investigators wish to investigate the efficacy of targeted repetitive transcranial magnetic stimulation (rTMS) on expressive language in patients with Alzheimer's disease (AD). In rTMS, magnetic pulses are used to noninvasively stimulate focal areas of cortex of about a square centimeter in area. rTMS has been approved in the United States for the diagnosis of peripheral nerve conditions. Depending on the frequency of stimulation, rTMS can preferentially stimulate or inhibit cortical areas. In stroke rehabilitation, for example, inhibition of the contralateral, uninvolved hemisphere by low frequency rTMS has improved movement of the affected limbs because of less aberrant inhibition of the affected hemisphere by the healthy hemisphere. The effects of rTMS has also been investigated and found to be useful in treating refractory depression and depression in Parkinson's disease. In addition, rTMS has improved naming in patients with Alzheimer's disease and has improved cognitive abilities and memory in non-demented older adults. Two studies found that rTMS improved aphasia in patients with stroke. While these studies are small, a review of the literature suggests that there may be a beneficial role for rTMS in patients with chronic neurological conditions. In addition, rTMS appears to be well tolerated, with transient headaches being the most common side effect. In this small open label study, the investigators wish to investigate the usefulness of bilateral stimulation of the brain region termed the dorsolateral prefrontal cortex (DLPFC) in patients with AD who have naming and language deficits.