Investigation of repetitive transcranial magnetic stimulation as a treatment for Alzheimer’s disease: treatment results and coil design considerations
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Date
2018-10-29
Authors
Rutherford, Grant Andrew
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Abstract
Alzheimer’s disease causes a significant burden to both society and individuals. As life expectancy increases worldwide, any potential mechanisms to help mitigate the effects of this disease will be highly desirable.
This document presents a body of work relating to Repetitive Transcranial Magnetic Stimulation (rTMS) as a possible treatment for Alzheimer’s disease. The results of a pilot study investigating potential cognitive benefits of rTMS in this population are presented. The pilot study achieved statistically significant results using the Montreal Cognitive Assessment (MOCA), and a long term follow up study showed a generally slower decline than expected for participants receiving treatment. A review and discussion of possible confounding effects of simultaneous depression treatment is presented.
Additionally, a simulated model of a standard TMS coil was analyzed to determine occupational safety limits from electromagnetic field (EMF) exposure for an operator while holding the coil to determine if this practice is safe. Using this model, published exposure guidelines are exceeded at 24.6 cm from the coil compared with 70 cm previously accepted. When an operator holds the coil, the electric field in the hand of an operator has an average strength of 9.9 V/m and a peak strength of 88.5 V/m. However, since the only known effects of EMF exposure in this frequency band are acute peripheral nerve stimulation, it is recommended that holding the coil during application should be considered safe.
Finally, an investigation of potential improvements in energy efficiency in rTMS systems is presented using a simulated model. Various geometric parameters such as radius, width, thickness, and number of turns are varied and the results are discussed, along with square coil and ferromagnetic core configurations. Coils are compared at fixed output strength by varying stimulator capacitance. Square coil configurations are found to be more efficient than round coils, ferromagnetic core coils can improve efficiency dramatically under certain configurations, and reductions in energy of at least 50% appear achievable.
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Keywords
rTMS, Alzheimer's disease, Electromagnetics, TMS coil design, Occupational safety
Citation
Rutherford, Grant, Rebecca Gole, and Zahra Moussavi. "rTMS as a Treatment of Alzheimer’s Disease with and without Comorbidity of Depression: A Review." Neuroscience journal 2013 (2013).
Rutherford, G., Lithgow, B., & Moussavi, Z. (2015). Short and long-term effects of rTMS treatment on Alzheimer's disease at different stages: a pilot study. Journal of experimental neuroscience, 9, JEN-S24004.
Rutherford, G., Lithgow, B., & Moussavi, Z. (2015). Short and long-term effects of rTMS treatment on Alzheimer's disease at different stages: a pilot study. Journal of experimental neuroscience, 9, JEN-S24004.