INS and Alzheimer disease: Supplementation with GABA in mice fed high fat diets promotes fat browning, which is involved in thermoregulation as opposed to energy storage, and regulates lipid metabolism.79,80 Transplantation of fecal material from lean donors into metabolic syndrome recipients has been shown to improve insulin sensitivity, altered microbiome composition, and changes in plasma metabolites including GABA.81 Thus, GABA’s role in AD may be peripheral or may affect both AD and associated comorbidities.