New research out of the University of California, Berkeley finds that some forms of stress are good for the brain. The study points to acute stress having a positive effect on brain performance; however, chronic stress is harmful.

Studying the brain function of rats, the researchers discovered that small amounts of stress improved mental performance of the brain. The exposure to acute stress caused stem cells of the rats' brains to reproduce new nerve cells rapidly. This abundance of new cells matured over a period of two weeks and improved the mental performance of the rodents.

"You always think about stress as a really bad thing, but it's not. I think intermittent stressful events are probably what keeps the brain more alert, and you perform better when you are alert," Daniela Kaufer, associate professor of integrative biology at the University of California, Berkeley said.

The research found that memory test performances were better in the rats exposed to acute stress.

"Where acute stress happens on a regular basis, it will keep the animal more alert," Kaufer said.

Also discovered during the research was that after acute stress exposure, nerve cell reproduction was triggered by the release of a protein called fibroblast growth factor 2 (FGF2). Deficiency of this protein is linked to depression in humans.

The research team wants to also investigate how memory performance is affected by both acute and chronic forms of stress. Prior research showed how chronic stress can suppress new neurons from being produced in hippocampus. The hippocampus is part of the cerebral cortex and is vital to short-term and long-term memory functioning.

Chronic stress increases glucocorticoid stress hormone levels and impairs memory. Chronic stress also increases the risk of obesity, heart disease and depression.

"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," Kaufer said. Details of the study were published in the journal eLife.