22 April 2013
Short, sharp stress can be good for us
Intermittent stressful events appear to keep the brain at optimal performance levels, say scientists at the University of California, Berkeley. "You always think about stress as a really bad thing, but it's not," said Daniela Kaufer, who has just completed a study that compared chronic stress to acute stress.
In studies on rats, Kaufer found that significant, but brief stressful events caused stem cells in their brains to proliferate into new nerve cells that, when mature two weeks later, improved the rats' mental performance.
Previous research has demonstrated that chronic stress elevates levels of glucocorticoid stress hormones, which suppresses the production of new neurons in the hippocampus, impairing memory. This is in addition to the effect that chronically elevated levels of stress hormones have on the entire body, such as increasing the risk of chronic obesity, heart disease and depression.
Less is known about the effects of acute stress, Kaufer said, and past studies have been conflicting. To clear up the confusion, the researchers subjected rats to acute but short-lived stress - immobilization in their cages for a few hours. This led to stress hormone (corticosterone) levels as high as those from chronic stress, though for only a few hours. The stress doubled the proliferation of new brain cells in the hippocampus. The researchers discovered that the stressed rats performed better on a memory test two weeks after the stressful event, but not two days after the event.
"In terms of survival, the nerve cell proliferation doesn't help you immediately after the stress, because it takes time for the cells to become mature, functioning neurons," Kaufer said. "I think the ultimate message is an optimistic one," she concluded. "Stress can be something that makes you better, but it is a question of how much, how long and how you interpret or perceive it."
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Source: University of California, Berkeley