In addition, associations between serum IGF-1 levels and cognitive function in patients with growth hormone deficiency (Webb et al. 2012; Licht et al. 2014), infantile spasms (Riikonen et al. 2010), Parkinson’s disease (Pellecchia et al. 2013), and delirium (Adamis and Meagher 2011) were reported. This evidence concerns the gene IGF1 and Parkinson disease.