BDNF and Parkinson disease: The results demonstrated that serum levels of mBDNF and mBDNF/proBDNF were significantly lower in the ex-PD group (19.73 ± 7.31 and 0.09 ± 0.05 ng/ml) as compared with the ex-NPD group (23.47 ± 8.21 and 0.15 ± 0.12 ng/ml) (p < 0.01 for both) and in the po-PD group (19.24 ± 7.20 and 0.09 ± 0.05 ng/ml) as compared with the po-NPD group (25.05 ± 7.67 and 0.16 ± 0.14 ng/ml) (p < 0.01 for both).