Disease progression and phenotypes of non-motor symptoms in Parkinson’s disease

Abstract

Background: Motor symptoms, non-motor symptoms, and treatment-related motor complications appear during the course of Parkinson's disease. Aim: To observe the progression of all symptoms related to Parkinson's disease including prodromal non-motor symptoms, motor symptoms, treatment-related motor complications, and non-motor symptoms. Methods: We assessed 201 patients with Parkinson's disease. The reviewed symptoms included all of the motor and non-motor symptoms listed in the Movement Disorder Society-Parkinson's disease criteria and other non-motor symptoms such as pain, fatigue, and apathy. According to established criteria, the presence of each symptom was coded. If present, latencies were calculated by months. To identify representative non-motor symptoms, we performed non-hierarchical and hierarchical cluster analyses. Results: We observed the presence of prodromal non-motor symptoms and the progression of motor symptoms, treatment-related complications, and non-motor symptoms. Regarding the non-motor symptoms, a comparison of the results from the two sets of cluster analysis led to the identification of six subgroups: “pain,” “constipation,” “depression and insomnia,” “hyposmia,” “daytime urinary urgency and symptomatic orthostatic hypotension,” and “excessive daytime somnolence, rapid eye movement sleep behavioral disorder, hallucinations, and dementia.”. Conclusions: In some patients, Parkinson's disease starts from the extra-striatonigral pathway. Apart from the motor symptoms and treatment-related complications, the non-motor symptoms progress independently in several directions, as a result of non-dopaminergic dysfunction, outside the nigrostriatal pathway.