Similarly to BDNF, also IGF-1 could be seen as a potential biomarker for neuroplasticity in PD, given the possible contribution of impaired insulin/IGF-1 signalling in PD pathophysiology, and the increased IGF-1 levels in serum and CSF of PD patients (Godau et al. 2010). This evidence concerns the gene IGF1 and Parkinson disease.