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

Overview

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.

Subjects for this study will be recruited from Dr. Devi's clinical practice. Eligible subjects must have a diagnosis of possible or probable Alzheimer's disease using NINCDS-ADRDA criteria. The patient and his or her legally authorized representative need to be available to sign the informed consent. The assent of the incapable subject will be obtained prior to enrolling the subject in the study. Once informed consent and assent are obtained, the subject will have a functional magnetic resonance imaging (fMRI) scan of their brain anytime during the 2 weeks prior to the first study visit. At Visit 1, subjects will undergo a baseline battery of cognitive tests lasting approximately 30 minutes. Subsequently, the subject will undergo rTMS. During the visit, Dr. Devi will locate the area of the brain to be stimulated and mark that area of the scalp with an indelible skin marker that will wash out over time. In addition, the subjects will be provided with ear plugs to use during stimulation. This process of locating the area to be stimulated will take about an hour and will occur once. Then rTMS will be started and this procedure will take approximately 20-30 minutes (please see the full protocol for a complete description of this process). Each rTMS stimulation session will last for about 30 minutes, 2 consecutive days a week for 2 weeks. Both immediately prior to the onset of the first rTMS session, and just after the end of the fourth and final rTMS session, subjects will be tested on their cognitive and language skills. These two testing sessions will last 30 minutes each. Subjects will have another fMRI scan anytime during the 2 days after the fourth and final rTMS stimulation session. Subjects will continue to receive usual care throughout the study period. Any changes to usual treatment will be noted in the study file. All subjects will be seen again 4 weeks after the final study treatment session and will once again undergo the brief cognitive battery and fMRI scan. The investigators expect to recruit two subjects at a time for the study and each subject will be enrolled for 5 weeks from the baseline visit.