GAD1 and Alzheimer disease: Analysis of GABAergic signaling components in post-mortem human brain tissue revealed significant transcriptional downregulation of GABA receptors (GABBR2, GABRA1, GABRB3, GABRG2), GABA synthesizing enzymes (GAD1, GAD2), and other neurotransmitter receptors (GRIK1, GRIK2), implicating a disruption in the excitatory/inhibitory balance that contributes to cognitive decline in AD [44].