GRM1 and Alzheimer disease: Conversely, sparse evidence exists on the role of cerebral mGluR1 in the pathophysiology of AD, although several studies have investigated the contribution of cerebellar mGluR1 to cerebellar ataxia (Aiba et al., 1994; Ichise et al., 2000; Ishibashi et al., 2016; Ishibashi et al., 2017; Notartomaso et al., 2013; Sillevis Smitt et al., 2000).