GRM5 and Parkinsonism: Moreover, full mGlu5 NAMs have even improved cognition in animal models of Fragile X (Michalon et al., 2014), Parkinson’s (De Leonibus et al., 2009), and Alzheimer’s Disease (Hamilton et al., 2016) reiterating mGlu5 function is relevant for cognition and effects on cognition (positive or negative) are also dependent on the underlying neurobiology of the disorder.