Effects of transcutaneous auricular vagus nerve stimulation in individuals with Parkinson's disease - a double-blind randomized controlled clinical trial

INTERVENTION: Participants will initially undergo a clinical screening to collect demographic and health data. Subsequently, eligible participants will be randomized into active transcutaneous auricular vagus nerve stimulation group and sham transcutaneous auricular vagus nerve stimulation group. The groups will consist of 13 participants, totaling 26 participants in the study. The evaluation will take place over two days. On the first day, questionnaires will be applied to assess disease staging (Hoehn and Yahr Scale); general impairment and disease progression (UPDRS); quality of life (PDQ‐39); cognitive function (Addenbrooke's Cognitive Examination); and involuntary movements (Abnormal Involuntary Movements Scale ‐ MSD Manual). Also on the first day, participants will be assessed for heart rate variability and upper limb tremor using an accelerometer. On the second day, functional tests will be carried out to assess gait (Time up and Go ‐ TUG and dual‐task TUG ‐ TUG‐DT); functional mobility (Sit and stand test five times); fine motor function and manual dexterity (Nine pin test); grip strength (hand dynamometer); and isokinetic assessment of the bilateral knee and elbow using an isokinetic dynamometer (Biode X4). After the two‐day evaluation, the intervention protocol will begin. The participants will be randomized between the groups by an independent researcher who will numerate the transcutaneous auricular vagus nerve stimulation equipment in different numbers (1 or 2) according to the programming of the equipment (active stimulation or sham stimulation). Only this independent researcher knows which equipment will be active stimulation or sham stimulation. This researcher will have no contact with the research participants.The intervention protocol consists of 12 sessions CONDITION: C10.228.140.079.862 Parkinson's disease PRIMARY OUTCOME: Evaluate the overall function of individuals with Parkinson's disease throught the Unified Parkinson Disease Rating Scale (UPDRS). The result will be assessed by comparing the score in the pre‐ and post‐intervention evaluation. It is expected that there will be no significant difference in most of the items on the assessment tool, with the exception of the motor section INCLUSION CRITERIA: Individuals of both sexes; aged between 40‐80 years, with a diagnosis confirmed by a neurologist of Parkinson's disease present in stages 1 to 3 of the Hoehn and Yahr scale; who have motor and cognitive complaints related to the Unified Parkinson's Disease Rating Scale (UPDRS) and who have been on stable Parkinson Disease medication for at least 30 days SECONDARY OUTCOME: Evaluate the cognition throught the Addenbrooke's Cognitive Examination. The result will be evaluated by comparing the score in the pre‐ and post‐intervention evaluation. It is expected that there will be no significant difference in the cognitive capacity of the participants Evaluate the fine motor function and manual dexterity through the Nine Hole Peg Test. The result will be evaluated by comparing the participants' fine motor function and manual dexterity measures in the pre‐ and post‐intervention evaluation. It is expected that there will be an improvement in the fine motor function and manual dexterity of the participants Evaluate the gait speed through the Timed Up and Go test (TUG). We will analyze the participants' gait speed using this test in the pre‐ and post‐intervention. The result will be evaluated by comparing the participants' gait speed measurements in the pre‐ and post‐intervention evaluation. Recent studies have shown that transcutaneous auricular stimulation of the vagus nerve improves different gait variables such as step length, stride velocity, stride length and step length variability. Therefore, transcutaneous auricular vagus nerve stimulation is expected to improve the gait of the participants Evaluate the grip strenght through the manual dynamometer. The outcome will be assessed by comparing the participants' grip strength scores at pre‐ and post‐intervention. It is expected that there will be no significant difference in the participants' grip strength Evaluate the heart rate variability through the Polar watch. The results will be evaluated by comparing the heart rate variability measurements of the participants in the pre‐ and post‐intervention evaluation. The studies show that the effect of transcutaneous auricular stimulation of the vagus nerve on heart rate variability is inconclusive. Therefore, it is expected that there will be no significant difference in the heart rate variability of the participants Evaluate the quality of life through the Parkinson's Disease Questionnarie (PDQ‐39). We will analyze the participants' scores on this evaluation instrument pre‐ and post‐intervention. The result will be evaluated by comparing the participants' scores in the pre‐ and post‐intervention evaluation. It is expected that there will be a significant difference in the participants' quality of life as a result of improved motor functions, as previous studies have shown Evaluate the upper and lower limbs strenght through the isokinetic dynamometer (Biode X4). The results will be evaluated by comparing the strength and peak torque measurements of the upper and lower limbs of the participants in the pre‐ and post‐intervention evaluation. It is expected that there will be no significant difference in the strength and peak torque of the participants