A systematic review on risk factors and protective factors related to Parkinson\'s disease

                                                                                       Background: Parkinson's disease is one of the chronic neurological diseases. It is the second most common neurodegenerative disease after Alzheimer's, affecting 7.5 million people worldwide and its rate is expected to increase by 20% by 2020. three symptoms of tremor, muscle stiffness and movement disorders are among the main diagnostic symptoms of the disease. The prevalence of Parkinson's worldwide varies between 18 and 418 cases per 100,000 people per year. It is generally estimated that the prevalence of this disease in the general population is 0.3%. A systematic review study was performed to determine the factors associated with Parkinson's disease. Methods: This study was a systematic review that was conducted by searching national and international databases until February 2020. Initially, all articles which had mentioned Parkinson-related factors were collected and accepted by researchers based on studies. Entry and exit criteria were met. Exclusion criteria included irrelevant items, duplication of studies, unclear procedure, and lack of access to the full text of the study. To reduce bias, articles were evaluated independently by two researchers, and the quality of articles was assessed using the STROBE checklist. All final articles submitted to the systematic review process were prepared by a template checklist. Checklists included article title, first author’s name, year of publication, place of study, risk factors, protective factors, and ineffective factors or the ones which their effects have not yet been determined, and the average age. Results: In these studies, the following risk factors were reported: family history, agricultural occupation, literacy, stress, well water consumption, aging, environmental factors, genetic factors, pesticide exposure, and alcohol abuse. On the other hand, factors such as smoking and oilseeds, high levels of B-complex vitamins, female estrogen hormones, and selenium have been reported to protect against Parkinson's disease. Conclusion: Considering the results of the present study and although there is no definitive treatment for this disease, protective factors and risk factors should be seriously considered by health policymakers for preventive measures.