The aim of the study is to examine the severity of sarcopenia in Parkinson's disease patients. Patients between the ages of 40-75 who have been diagnosed with Parkinson's disease by a neurologist and healthy individuals with similar demographic characteristics will be included in the study as a control group. The staging of Parkinson's patients will be done with the Modified Hoehn and Yahr Scale, and the severity of the disease will be done with the Unified Parkinson's Disease Rating Scale. Within the scope of the study, anterior thigh thicknesses of individuals with Parkinson's disease will be evaluated with ultrasonography. Sarcopenia severity will be determined with the ISarcoPRM algorithm using the ultrasonographic evaluations of the individuals. It is planned to include 80 Parkinson's patients in the study. Parkinson's patients between stages 1-3 according to the Modified Hoehn and Yahr Scale will be included in the study.