IGF1 and Parkinson disease: Low levels of the Insulin-like growth factor 1 (IGF-1) is a risk factor for developing neurodegenerative disease (Westwood et al., 2014) and modulation of IGF-1 by estrogens is thought to cause slower progression of Parkinson’s disease in women compared to men [reviewed in González et al. (2008); reviewed in Labandeira-Garcia et al. (2016); reviewed in Castilla-Cortázar et al. (2020)].