March 30, 2007

Brain Awareness speaker probes impact of stress

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Stanford University’s Robert Sapolsky, Ph.D., delivers the Brainstorm Keynote Address. (photo by Susan Urmy)

Brain Awareness speaker probes impact of stress

It was an upholsterer who really discovered the characteristics of the “type A” personality profile, Robert Sapolsky, Ph.D., told the crowd at last week's Brainstorm Keynote Address.

Noting the strange pattern of wear-and-tear on the waiting room chairs in a cardiology practice, the upholsterer asked the doctor who would later describe the driven, time-pressured behavior, “What is wrong with your patients?”

Showing a photograph of a chair worn on the front two edges and armrests, Sapolsky said, “this is the type A profile: this is the person sitting at the edge of the seat and squirming and clawing at the armrests.

“If you are type A, that's more of a risk factor for heart disease than if you smoke, are overweight, have elevated cholesterol levels … it's a huge component.”

The upholstery story was one of many tales peppering a lecture frequently interrupted by laughter. Sapolsky, the John A. and Cynthia Fry Gunn Professor of Biological Sciences, Neurology and Neurological Sciences at Stanford University, took the audience on a whirlwind tour through the stress response and why chronic stress causes disease.

Citing the zebra about to become a meal and the lion running after it, Sapolsky, the author of “Why Zebras Don't Get Ulcers,” described the components of the stress response — what our bodies do when the external world presents a “stressor.”

“Whether you're that zebra or that lion, there are certain things you need to do with your body,” he said. “First off, you need energy … so you go to your fat cells, your liver, you go to the bank and empty the savings accounts and turn it into cash: sugar in the bloodstream.”

To speed delivery of the sugar to the sites where it's needed, heart rate, blood pressure, breathing rate and cardiovascular tone all increase. And the “long term building projects” shut down; there is suppression of digestion, growth, reproduction and the immune system.

Stress hormones getting into the brain cause increases in dopamine secretion, which in the short term sharpens cognition, alertness, pleasure and memory.

“If you plan to get stressed like a normal mammal, you had better turn on the stress response,” Sapolsky said. “But what if you turn on the stress response too long, too often, for purely psychological reasons? You're going to be more at risk for disease.”

The long list of stress-induced diseases includes hypertension, atherosclerosis, type 2 diabetes, ulcers, suppression of growth, suppression of reproduction (amenorrhea/anovulation in women, erectile dysfunction in men), suppression of immunity, memory loss and depression.

Sapolsky has focused for 25 years on what chronic stress does to the brain.

“Those same hormones that in the short term have all those great effects, long term do all sorts of bad stuff.”

Chronic stress kills neurons in the hippocampus, a brain region involved in learning and memory. Sapolsky and colleagues have characterized the cellular and molecular biology underlying this effect. Chronic stress depletes the reward pathways, causing anhedonia, the defining symptom of depression.

Depression, he said, is the textbook psychiatric disorder of stress, and in the last few years there have been “a spate of studies showing atrophy of the hippocampus in major long term depression, and the longer the depression, the greater the atrophy, with no evidence that this can reverse over time.”

We can combat our stress with outlets for our frustration, a sense of control and predictability, the perception of the reality as getting better, and a shoulder to cry on, he said.

“None of us are being ripped apart by lions. We all have the luxury of coming up with a psychogenic stress response. The most important point is: insofar as we are smart enough to invent that stuff and foolish enough to fall for it, all of us have the potential to be wise enough to keep it in perspective. Good luck with your stressors.”

The Brainstorm Keynote Address was sponsored by the Vanderbilt Kennedy Center, Center for Molecular Neuroscience, Department of Psychology, Chancellor's Office, Developmental Psychopathology Research Training Program, Department of Psychiatry, Department of Neurology, Vanderbilt Brain Institute, and the Middle Tennessee Chapter Society for Neuroscience.