Dorsal Raphe Nucleus: Seam for Earliest Detection of Tau and Symptoms

The dorsal raphe nucleus (DRN), a small brain region that produces serotonin, is among the first to be vulnerable to tau. Using new methods, we will map tau in the DRN, track its spread to other brain regions, and link it to mood and cognition to improve the earliest detection of Alzheimer’s disease

The dorsal raphe nucleus (DRN, Latin:”seam”), a tiny brainstem region providing serotonin, regulates behavior and cognition and is one of the first regions vulnerable to tau. Due to its size, DRN tau has only been investigated at autopsy. Taking advantage of new methods, we will examine tau patterns in the DRN, changes in DRN tau, spreading of tau to other brain areas and “seam” DRN tau to cognitive and behavioral changes. The outcomes of this innovative project will inform the field on the earliest brain changes in Alzheimer’s disease, improve early detection and design of clinical trials.

This project is the first to measure and track tau within the dorsal raphe nucleus (DRN, latin for seam) of living individuals. This is made possible by a novel method that enables us to extract tau information from very small brain regions, such as the DRN. By integrating these methods in two large studies, we can relate DRN tau to the first behavioral and cognitive changes of Alzheimer’s disease. In a smaller study, we will examine the relationship between DRN serotonin activity and tau accumulation. Together, using innovative methods, this project uniquely contributes to improved early detection and links this to new insights for future treatments aimed at halting disease progression.

The results of this research could shift the detection of Alzheimer’s disease years earlier than currently possible, identifying biological warning signs before memory problems emerge. Earlier detection opens the door to earlier intervention and more effective prevention trials. For the research field, our findings will provide important insights into the role of the brain’s serotonin system in Alzheimer’s disease and could point toward repurposing existing antidepressant medications as targeted therapies for certain individuals.