Transcranial Photobiomodulation as a Therapy for Patients With Parkinson's Disease: Relationship Between Pain and Brain Functional Connectivity

Parkinson's disease is a progressive and degenerative neurological movement disorder that affects thousands of people. The disease is characterized by presenting motor and non-motor symptoms, as the disease progresses, it becomes more disabling, making it impossible for the individual to perform simple tasks. A non-motor symptom increasingly reported by patients and undertreated in clinical practice is pain. During the past few decades, possible neural substrates of pain have been studied extensively, resulting in a potential network of connected brain areas that are believed to underlie pain processing and experience. There is no definitive consensus on all areas involved in such a pain network; however, pain-related regions consistently found across all studies include the thalamus, anterior cingulate cortex (ACC), posterior and anterior insula, amygdala, prefrontal cortex (PFC), secondary somatosensory cortex (IBS), and periaqueductal gray (PAG). With the aim of helping to improve the painful condition, non-pharmacological therapies have been studied, and one of them is phototherapy, a non-invasive method used by several areas of health, which has been shown to be increasingly effective in the treatment of decreased pain sensitivity. The present study aims to evaluate the effects of transcranial photobiomodulation in patients with Parkinson's disease. This is a randomized study, in which investigators will analyze the effect of FBM on pain control and on magnetic resonance images to better elucidate the connectivities of pain areas. Afterwards, the researchers will carry out a better elaboration on the treatments of individuals diagnosed with Parkinson's disease, the researchers will evaluate the pain through questionnaires, and the researchers will also evaluate the motor cognitive capacity of these patients before and after the therapy.