The effects of cerebellar transcranial alternating current stimulation on hand tremor in Parkinson s disease: a preliminary study

Parkinson s disease (PD) is a neurodegenerativedisorder with motor and cognitive symptoms. Tremor is animportant symptom of this disease. Since the discovery ofdopamine concentration depletion in the basal ganglia, they havebeen the clinical and research targets in PD. However, increasinganatomical, pathophysiological, and clinical evidence suggestedthat the cerebellum may substantially contribute to the clinicalsymptoms of PD. This study aims at investigating the effect of thecerebellum on tremor. First, a head model was presented, followedby applying tACS on six PD patients for 15 minutes at eachpatient’s peak frequency. Recording PD patients’ post-stimulationrest and action tremors is performed in this study for the very firsttime. A tri-axial accelerometer was placed over the index finger ofeach patient’s dominant hand. The average magnitude of the poststimulationrest tremor decreased significantly (P-value = 0.0313),compared to its pre-stimulation counterpart. The average medianfrequency and the spectral energy of the post-stimulation rest andaction tremors increased in comparison to the pre-stimulationtremors. Our findings suggest that the cerebellar tACS could beuseful in suppressing the PD tremor.