Reduced cerebrospinal fluid mitochondrial DNA is a biomarker for early-stage Parkinson's disease.

The identification of cell-free circulating mitochondrial DNA (ccf-mtDNA) in early-stage Alzheimer's disease (AD) raised the possibility that the same neurodegenerative effect could be observed in Parkinson's disease (PD). Here, and for the first time, we investigated the role of ccf-mtDNA in PD, identifying a significant reduction of ccf-mtDNA in PD patient cerebrospinal fluid (CSF) when compared to controls. Our data demonstrates that CSF ccf-mtDNA is not only a powerful biomarker for PD, but, given that the effect is also observed in AD, is likely a biomarker for neurodegeneration.