RecruitingProcedureParkinson's Disease Biomarkers in Nerve Cells in the GutParkinson's disease affects all the nerve cells in the body, including the ones in the gut. The gut contains its own nervous system, the enteric nervous system, and can be thought of as a "second brain". This second brain can reflect what is going on in the actual brain. This study is being done to look for biomarkers, or early indicators of developing Parkinson's disease, in the microbiome and in the gut tissue taken during routine screening colonoscopy. People aged 45 and over who are due for their routine screening colonoscopy are eligible to participate.