L-theanine combined with luteolin could prevent symptoms similar to Alzheimer’s disease (AD) in rat models injected with amyloid-β (25–35) into the hippocampal CA1 region, and this was mainly associated with the improvement of hippocampal insulin signaling, norepinephrine metabolism, and the mitigation of neuroinflammation (48). This evidence concerns the gene INS and Alzheimer disease.