Mounting evidence indicates that chronic exposure to emotional stressors, such as anxiety or fear, can make a person more susceptible to Alzheimer's disease. The latest study comes from a team at the Salk Institute for Biological Studies in San Diego that replicated the body's reaction to mild stress by physically restraining mice for half an hour. The incident modified the tau protein, which gives neurons structural support, rendering it unable to fulfill its role. “This conversion is a key event in the development of Alzheimer's,” says Robert A. Rissman, lead author of the study. After a single stress episode, tau morphed back into its original state within 90 minutes. When the team induced stress every day for two weeks, however, tau remained in its modified state long enough to allow the individual protein molecules to clump together. These protein heaps are the first step toward neurofibrillary tangles, one of the hallmarks associated with Alzheimer's.