While implicated in psychiatric disorders (Woźniak et al., 2016; Isherwood et al., 2017), learning and memory (Davis et al., 2013; Iscru et al., 2013), and neurodegenerative disease (Niswender et al., 2016), the role of GRM4 in cognition is not well understood. This evidence concerns the gene GRM4 and neurodegenerative disease.