SNCA and Cognitive impairment: These include glutamate ionotropic receptor AMPA type subunit 4 (Gria4) and synuclein alpha (Snca).72,73 In a proteomic approach performed on postmortem human brains with AD and Parkinson’s disease with dementia (PDD), and dementia with Lewy bodies (DLB), a significant correlation was found between cognitive impairment and loss of Gria3 protein before death.