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UBC Theses and Dissertations

Personalized stimuli as treatment for resting tremor in Parkinson's disease Cheung, Marcus Ting Hin


Resting tremor in Parkinson’s disease (PD) affects quality of life and individuals’ ability to complete activities of daily living. Resting tremor has been shown to respond to transcranial alternating current stimulation (tACS) when delivered out of phase with the tremor. The present work aimed to further investigate potential tACS-based treatment mechanisms by designing and delivering personalized stimuli and extend our understanding of Parkinsonian resting tremor. Nine participants with tremor dominant PD received fourteen unique tACS stimuli to Primary Motor Cortex (M1) and Supplementary Motor Area (SMA). Effect on tremor was measured before and during stimulation via a 9 degree of freedom (DoF) motion sensor. The first principal component score was obtained from Principal Component Analysis (PCA) of these measures and the power of the data was compared before and during stimulation using a two-sample t-test. Four custom stimuli were designed by weighted linear combination of the data with the greatest effect on tremor; two of which were designed to be suppressive and two were designed to be augmentative towards tremor. Average power was calculated following delivery of the personalized and non-personalized stimuli. Regardless of whether tACS was delivered as a personalized or non-personalized stimuli, results indicate an increased average power during stimulation compared to no stimulation and an overall trend towards augmentation of tremor across participants. Supporting analyses, including Multivariate Empirical Mode Decomposition (MEMD) reinforce this finding, showing no clear trend towards any specific frequencies contributing to tremor suppression. The present results suggest that a broad spectrum frequency-based approach is not an effective means of suppressing tremor in people with PD and a phase-based or more targeted frequency approach may have more promise as a treatment mechanism for resting tremor in PD.

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