Hustling up the escalator, I didn't have time to appreciate the irony of my situation: I was running late to a session on stress. It was with more than strictly professional interest then, that I settled in to hear 5 researchers discuss their latest findings on stress and the brain.
In some ways, stress is all in our heads, said Bruce McEwen, a neuroendocrinologist at Rockefeller University in New York City, since our brains are responsible for recognizing and responding to stressors. Three sections in particular: the amygdale, the hippocampus, and the prefrontal cortex work with the hypothalamus to flip on (and hopefully shut down) production of stress hormones and other automatic responses to stress, like increased heart rate. But researchers are now learning how stressors can physically alter our brains, which in turn, may impact how we learn, form memories, and even make decisions. The effects are sometimes reversible but sometimes not, the scientists reported.
Among the findings:
Stress the monkey. Simona Spinelli of the National Institutes of Health in Bethesda, Maryland and colleagues placed 13 young monkeys in the care of their peers for 6 months, while another 15 monkeys spent the same time with their mothers. Both sets of monkeys then rejoined typical social groups, and the researchers scanned their brains after several months of exposure to the normal environment. The monkeys raised under Lord of the Flies-like conditions showed enlarged brain regions in areas related to stress, compared to the control group, even after spending time in the normal environment. This suggests that early stress can have long-lasting impacts on the brain, Spinelli says, though follow-up studies in humans are necessary.
Upsetting the balance. Neurobiologist Tallie Baram of the University of California, Irvine, and her colleagues looked at how short-term, but acute, stress impacts the adult brain. They found that the brain produces a different type of stress hormone, called corticotrophin-releasing hormone (CRH), in response to short-term stressors, like sitting in the waiting room while a loved one undergoes major surgery. Just a few hours of CRH exposure was enough to destroy what Baram calls the "delicate balance" between the parts of dendrites that send and receive synapses.
Brain shrink. Fred Helmstetter of the University of Wisconsin in Milwaukee examined the effect of chronic stress, akin to post-traumatic stress disorder, in adult rats by examining their hipocampal volumes. They found that this memory-forming region of the brain actually shrank slightly in rats exposed to chronic stress, which sheds some insight for the controversy of whether Post Traumatic Stress Disorder (PTSD) can actually shrink the hippocampus or if people with smaller hippocampuses may be more prone to the syndrome.
Many of these studies have implications for how stress impacts our ability to learn and form memories, the researchers reported. And scientists at the University of Washington in Seattle are also starting to examine whether stress interferes with decision-making capacities. With all this talk of stress, Thanksgiving vacation couldn't come any sooner.