Blocking the kynurenine pathway, a regulator of brain metabolism, can restore cognitive function in lab mice with Alzheimer’s disease. The pathway is overactivated in Alzheimer’s, disrupting glucose metabolism and starving neurons of energy. By inhibiting this pathway, researchers improved memory and brain plasticity in mice, offering hope for new treatments in humans. IDO1 inhibitors, currently in cancer trials, could be repurposed for Alzheimer’s treatment.