Stress can damage a part of the brain involved in learning and memory, called the hippocampus. New studies provide clues into how that happens and what we can do to prevent it.
Copyright (c) 2008 BrainFit For Life
Remember the Bugs Bunny cartoons where Yosemite Sam would get so angry and stressed out that steam would come out of his ears. In fact, this seemed to happen to a lot of cartoon characters that lost there cool. Were these guys actually frying there brains? If so, could they get those fried brain cells back after they calmed down? It seems that cartoonists may have correctly predicted some neurobiology of stress.
Stress biology has been a hot topic in neuroscience for many years and research emerges all the time to further our understanding of why stress is so bad for the brain. A new study reveals an important finding that sheds more light on maintaining brain fitness during these bouts of stress. But before getting into the new data, let's back up a little.
Robert Sapolsky, a neuroscientist at Stanford, has been a prevailing voice in stress biology for some time. He proposed theories over a decade ago that suggested stress was actually killing brain cells in a part of the brain called the hippocampus, a structure crucial for learning and memory.
In fact, the last ten years or so have revealed some interesting things about the hippocampus, especially as it relates to stress. Contrary to years of dogma, we discovered that the hippocampus is an area of the brain that is continually giving birth to new neurons. For many years, we believed that the brain was incapable of making new neurons after development, but we now know that's not true. New neurons are being born (and dying) in the hippocampus all the time.
The trick is to keep the rate of neuron birth in check with that of neuron death. If you lose more neurons than you gain, your hippocampus can shrink and whither; and your ability to learn and remember declines.
Sapolsky's early work showed that stress was a bad thing for this process. Stress slowed the rate of new neuron birth, to tip the scales in favor of neuron death. Not only does this hamper your cognitive abilities, but it may leave you more susceptible to prolonged stress and create a viscous cycle.
Later work by a Yale researcher, Ron Duman, showed that anti-depressants often require new neuron birth in the hippocampus to have their affect. One a side-note, exercise is one of the most potent ways to stimulate new neuron birth in the hippocampus. This is probably why exercise is such a great anti-depressant.
New research from Duman's group has now pinpointed on of the big players in how stress works to stop neuron birth in the hippocampus. They discovered a molecule called IL-1beta (Interleukin-1 beta) is responsible for putting the breaks on hippocampal neuron birth. We already knew that IL-1beta is a hormone involved in inflammation, increased by stress. We also knew that IL-1beta, itself, could increase some effects of stress.
What the new finding tells us is that if we focus on reducing IL-1beta during unhealthily long periods of stress, we may counter some of the cognitive problems that too much stress creates. I'm sure this discovery has peaked the interest of many pharmaceutical companies with anti-IL-1beta drugs, but there is already a simple way to reduce this hormone.
Previous studies showed that omega-3s can reduce many hormones involved in inflammation and that they can specifically counteract increases in stress, caused by IL-1beta. Putting this older research in light of the new study, suggests that omega-3s might actually be able to protect the hippocampus during stress.
So again, discoveries in molecular biology take us back to benefits of brain fitness cornerstones that we have been promoting for some time; in this case, exercise and quality nutrition. Exercise can increase the birth of new neurons in your hippocampus and omega-3s may protect them from stress-induced IL-1beta.
References: PNAS 2008 105(2) 751-756 J. Lipid Res. 2003 44(10):1984-91
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