Dopamine Dysfunction Linked to Memory Loss in Alzheimer’s Disease

A study led by Kei Igarashi, Distinguished Professor at Tohoku University School of Medicine, in collaboration with the University of California, Irvine, has identified dopamine dysfunction as a key driver of memory loss in Alzheimer’s disease. Published in *Nature Neuroscience* on April 23, 2026, the research focused on the entorhinal cortex—a brain region critical for memory processing—where dopamine levels in Alzheimer’s mice models dropped to less than 20% of normal levels. The team observed severe impairments in associative memory during odor-based learning tasks, alongside abnormal neural responses in the entorhinal cortex. To test whether dopamine restoration could reverse these effects, the researchers used optogenetic techniques and Levodopa, a Parkinson’s drug. Both interventions normalized neural activity and improved memory performance in the mice. Igarashi noted that dopamine dysfunction plays a central role in Alzheimer’s-related memory decline, offering a potential new therapeutic target. Current treatments focusing on amyloid-β and tau proteins have shown limited success, but the findings suggest dopamine-based therapies could help slow or reverse cognitive decline. The study, titled *Early dopamine disruption in the entorhinal cortex of a knock-in model of Alzheimer’s disease*, was conducted by a team including Tohoku University and UC Irvine researchers. The discovery opens new possibilities for treating millions of Alzheimer’s patients worldwide, potentially bringing closer the goal of restoring lost memories.