An exploration of the effects of audio-visual entrainment on Parkinson´s disease tremor

A significant proportion of patients affected by Parkinson´s disease (PD) suffer from drug-resistant tremor, which often eventually progresses to disabling and distressing levels. Recent literature on PD indicates that such tremor is associated with corresponding oscillations in the thalamus. In this research, we wanted to explore the possibility that affecting such oscillations via a form of external audio-visual periodic stimulation (known as entrainment) might also have an indirect effect on PD tremor. Results with three PD patients have been encouraging, with all three showing a marked reduction of their tremor during the intervention with entrainment at approximately 10 Hz. However, in control sessions where stimuli presented no entraining oscillations, a very similar pattern of reduction in tremor was observed. This suggests that such a reduction is more likely due to the state of relaxation induced by both protocols than to an actual direct interference of the entrainment frequencies with the tremor frequencies.