Long-term stress harms, but short-term stress can help us
Scientists have long known that long-term stress can have devastating effects on our health, but according to new research published April 16 in the journal eLife, short-term stress may actually cause new cells to develop in our brains and therefore improve our future mental performance.
"You always think about stress as a really bad thing, but it's not," said Daniela Kaufer, associate professor of integrative biology at the University of California, Berkeley. "Some amounts of stress are good to push you just to the level of optimal alertness, behavioral and cognitive performance."
Based on the two distinct ways we experience stress, acute (or short-lived) stress and chronic (or long-term stress), new research conducted by Kaufer and UC Berkeley post-doctoral fellow Elizabeth Kirby has discovered precisely how acute stress, not chronic, primes the brain for improved performance.
In experiments conducted on rats, Kaufer and her research team found significant, yet brief stressful events caused their stem cells to multiply, creating new nerve cells that improved the rats’ mental performance when the new cells matured two weeks later.
"I think intermittent stressful events are probably what keeps the brain more alert, and you perform better when you are alert," Kaufer said.
Unfortunately, the same does not hold true for chronic, long-term stress. Stress over a longer period of time can be severely damaging to our health, causing us to suffer from insomnia, depression, and even serious illness.
Prior research has clearly shown that chronic, long-term stress suppresses development of new neurons in certain portions of the brain, taking a toll on memory and causing problems with focusing. But how short-term stress affects memory has not previously been as clear. So Kaufer and her team focused their research on the effects of stress on the brain’s hippocampus, which plays a critical role in memory.
In the experiment they conducted by subjecting rats to brief stressful events, they found that the short-term stress appeared to double the amount of new brain cells in the hippocampus compared to control animals.
The stressed-out rats also performed better on a memory test two weeks after their experiment, but not until two weeks later. Using cell labeling, the researchers confirmed that the nerve cells involved in learning the new tricks two weeks later were the same new ones that developed following the stressful event.
The research conducted by Kaufer and researchers at UC Berkley suggest that short-term stress could also improve human mental performance. Indeed, previous studies have demonstrated that moderate amounts of stress can help us better perform tasks while improving memory.
For example, one study showed that people who experience moderate levels of stress before surgery have a better recovery than those with high or low levels of stress. A more recent study revealed that stress may help prevent breast cancer because it suppresses the estrogen production – and, earlier this year, a Johns Hopkins study found that children of mothers who had higher levels of the stress hormone cortisol during pregnancy were developmentally more advanced than those born to women with lower levels.
This moderate stress is similar to the rush we experience when our hormones kick in, enabling us to meet certain challenges with a sense of control and accomplishment. According to experts, this “good” stress stimulates us, helping to improve our heart function and strengthening the body’s ability to fight infection. It’s also thought by some that short-term boosts of moderate stress can help protect against Alzheimer’s by keeping brain cells working at peak capacity.
SOURCE: eLife research article: Acute stress enhances adult rat hippocampal neurogenesis and activation of newborn neurons via secreted astrocytic FGF2, April 16, 2013 DOI: http://dx.doi.org/10.7554/eLife.00362