Linking stress and senility

Studies have suggested that emotional stress can increase a person’s risk of developing Alzheimer’s disease. Now, scientists have found a gene that may explain the connection.

Paul E. Sawchenko of the Salk Institute for Biological Studies in La Jolla, Calif., and his colleagues turned their attention to a gene called type 1 corticotropin-releasing factor receptor (CRFR1), because it’s widely involved in the brain’s responses to stress.

Scientists had shown that mice subjected to extreme stress—whether by forced swimming in cold water, starvation, or heat—develop clumps of insoluble proteins called neurofibrillary tangles in their neurons. Such tangles form, along with plaques, in the brains of Alzheimer’s patients.

“We wanted to know if emotional stressors that are much milder and more like the ones people experience every day would have the same effect,” says Sawchenko.

To create mild stress, the scientists physically restrained mice in tubes for 30 minutes each day. After 2 weeks, the mice had developed the protein tangles in their brain cells. Mice that hadn’t been restrained developed no tangles.

However, mice engineered to lack CRFR1 didn’t develop tangles even after being restrained, the scientists report in the June 13 Journal of Neuroscience.

Several pharmaceutical companies are developing antianxiety drugs that block the protein made by CRFR1, and Sawchenko suggests that researchers might investigate these drugs for use in Alzheimer’s patients.