If you think stress is making your brain old and befuddled before its time, you may be right. Researchers know that areas of the brain associated with learning memory can deteriorate with age. And neuroscientist Philip Landfield of the University of Kentucky wondered whether stress accelerated that change. Using mild electric shocks, he trained rats to move across a plastic runway when a buzzer sounded. Then he buzzed at random. Not knowing when to expect an alarm, the rats spent the whole time--four hours a day--in a tizzy.
After six months, Landfield's team studied the rats' brains. In young stressed-out rats, nerve cells were less active than in laid-back counterparts--indicating their ability to learn and remember was at least temporarily impaired. In older rats, stress sped up the actual loss of brain cells. No one has yet shown such a direct link between stress and aging in humans, says Landfield. But, he notes, people who develop Alzheimer's disease might be especially vulnerable to stress. And if scientists can learn why stress is more harmful to elderly brains, they may also find clues to Alzheimer's. Meanwhile, says Landfield, "it seems prudent to avoid prolonged stress."