Dr. Hans Selye, the father of stress research, mapped the hormonal pathways shown in the illustration above some 40 years ago. Since then, scientists have found that stress provokes a number of even subtler chemical changes in the body that may have profound effects on health, both physical and mental. "There is a constant intertwining of stress systems," says Stanford Neurochemist Jack Barchas. "It's much like a symphony."
Over the past two decades, researchers have learned that stress triggers chemical changes in the brain. Particularly sensitive to emotional strains are the concentrations of...