Assessment of Transcranial Electrical Stimulation and Auditory Stimulation During Walking in Parkinson Patients

According to the World Health Organization (WHO), Parkinson's disease affects 1 in 100 people over the age of 60. Currently, there are about 7 million people with this disease in the world and the WHO predicts that by 2030 they will reach more than 12 million.

Parkinson's disease (PD) is a progressive disease of the nervous system that affects movement, produced by the destruction of dopaminergic neurons found in a region of the brain called the basal ganglia. This disease usually affects people over 60 years of age, whose symptoms worsen as the disease progresses and in many cases the ability to function in everyday situations is greatly affected. Due to decreased levels of dopamine, motor symptoms such as tremor, stiffness, slowness of movement, postural instability and other non-motor symptoms such as depression, hallucinations, insomnia and dysfunction of the autonomous organic systems, for example, digestion and blood pressure, as well as alteration in the expression of emotions. Over time, different strategies have been developed to treat and slow the progress of the disease, including pharmacological, rehabilitative and even surgical treatments.

Transcranial direct current stimulation (tDCS) is a brain stimulation technique that delivers a low-intensity electrical current to the scalp, usually between 1 and 2 mA over approximately 5 to 30 minutes. During tDCS, most people feel a slight tingling, pricking, itching or warmth, however, these sensations are not painful and disappear when the stimulation is stopped. The tDCS technique is used with the aim of enhancing a specific brain activity through the neuromodulation of neuronal excitability. In pathologies such as PD, these therapies have been shown to induce immediate after-effects in the brain that translate into reduced gait freezing and improvements in executive function and mobility. In addition, the combined effects of tDCS and physical therapy on the walking ability of PD patients have been studied, where it was shown that anodic tDCS and physiotherapy could be used as a combination treatment to improve patients' gait speed.

Another potential therapeutic tool in the treatment of PD consists of the use of sound stimulation with beat frequencies similar to the step. Sounds, mainly rhythm, have also been shown to improve gait characteristics (speed, time and cadence of passage) and eliminate frozen gait, characteristic in this type of population. Sound strategies such as Binaural Beats (BBs) improve the ability of upper and lower limb movements in PD patients. Specifically, this technology is characterized by presenting two tones of different frequencies for each ear in order to influence the mood and mental performance of the listener. In accordance with the above, this protocol is proposed in order to evaluate the effect of tDCS combined with auditory and binaural stimulus strategies during gait therapy in patients with Parkinson's disease.