It has been reported previously that SNCA mutation carriers have more frequent and more severe dementia, rapid progression, hallucinations and autonomic dysfunction (Muenter et al., 1998; Farrer et al., 2004; Fuchs et al., 2007; Ahn et al., 2008; Nishioka et al., 2009; Puschmann, 2013; Bonifati, 2014; Kasten et al., 2017; Schneider and Alcalay, 2017). This evidence concerns the gene SNCA and dementia.