Parkinson's disease affects more than 10 million people worldwide and is considered an endemic condition. "By the time the motor symptoms of Parkinson's disease appear, 50 -- 80 per cent of the relevant brain cells are often already damaged or gone. This pattern appeared only in people in the early phase of Parkinson's disease. The researchers estimate that within five years, blood tests designed to identify Parkinson's disease at an early stage could begin to be tested in healthcare systems. More About the Scientific ArticleThe study Longitudinal assessment of DNA repair signature trajectory in prodromal versus established Parkinson's disease has been published in npj Parkinson's Disease.