MDS-UPDRS: The International Parkinson and Movement Disorder Society sponsored revision of the Unified Parkinson's Disease Rating Scale; LD/CD: levodopa/carbidopa; CGI-C: Clinical Global Impression of Change; UPDRS: Unified Parkinson's Disease Rating Scale; PDQ-39: Parkinson's Disease Questionnaire; DA: dopamine; MAO-B: monoamine oxidase-B. Here, MAOB is linked to Parkinson disease.