A possible mechanistic link between stress and the development of Alzheimer tangles

Top left: In unstressed animals the hippocampus, which is involved in the formation of memories and learning, is free of phosphorylated tau. Top right: Subjecting mice to low-level chronic emotional stress -- the kind we experience in everyday life—leads to widespread tau phosphorylation, a key step in the formation of neurofibrillary tangles (black streaks), one of the hallmarks of Alzheimer's disease. Bottom: While acute stress effects are reversible, repeated stress leads to cumulative increases in phosphorylated tau, a portion of which is sequestered in an insoluble, and potentially pathogenic, form. Credit: Image courtesy of Dr. Paul E. Sawchenko and Dr. Robert A. Rissman, Salk Institute for Biological Studies