DLG4 and Cognitive impairment: In this study, we have carried out immunochemical assays to estimate the relative expression of presynaptic protein synaptosome-associated protein 25 (SNAP25) and postsynaptic density protein 95 (PSD95) in different brain regions in cognitively unimpaired subjects (CU), subjects with ADD, and subjects with moderate levels of AD pathology that were either cognitively unimpaired (CU) or had mild cognitive impairment (MCI).