The therapeutic potential of IGF-1 has been demonstrated in animal models of a number of neurodegenerative diseases such as cerebellar ataxia (Fernandez et al., 2005), multiple sclerosis (Chesik et al., 2007) and, as mentioned above, Parkinson disease (Ebert et al., 2008) and Alzheimer disease (Fernandez and Torres-Aleman, 2012), in which treatment with IGF-1 alleviates neurological symptoms. Here, IGF1 is linked to Parkinson disease.