BDNF and Parkinson disease: In cross-sectional comparison, mBDNF/proBDNF showed stronger correlation with PD diagnosis than did serum mBDNF level either at initial diagnosis or follow-up, with differences statistically significant, suggesting that mBDNF/proBDNF as one of the diagnosis clues for PD might be better than mBDNF and proBDNF alone.