Why Zebras Don't Get Ulcers: The Acclaimed Guide to Stress, Stress-Related Diseases, and Coping

by Robert M. Sapolsky

“sleeping on a problem,”

A critical realization roared through the research community: the physiological stress-response can be modulated by psychological factors.

loss of control or predictability, loss of outlets for frustration or sources of support, a perception that things are getting worse.

would describe it as a “genetic/neurochemical disorder requiring a strong environmental trigger whose characteristic manifestation is an inability to appreciate sunsets.”

anhedonia is “the inability to feel pleasure” (also often called dysphoria—I’ll be using the terms interchangeably).

The best evidence suggests that depression involves abnormal levels of the neurotransmitters norepinephrine, serotonin, and dopamine.

One region regulates processes like your breathing and heart rate. It includes the hypothalamus, which is busy releasing hormones and instructing the autonomic nervous system.

If your blood pressure drops drastically, causing a compensatory stress-response, it is the hypothalamus, midbrain, and hindbrain that kick into gear.

On an incredibly simplistic level, you can think of depression as occurring when your cortex thinks an abstract negative thought and manages to convince the rest of the brain that this is as real as a physical stressor.

Given these functions of the ACC, it is not surprising that its resting level of activity tends to be elevated in people with a depression—this is the fear and pain and foreboding churning away at those neurons.

For example, induce a positive state in someone (by asking him to describe the happiest day of his life), and the left PFC lights up, in proportion to the person’s subjective assessment of his pleasure. Ask him to remember a sad event, and the right PFC dominates.

Moreover, the excessive secretion of glucocorticoids is due to what is called feedback resistance—in other words, the brain is less effective than it should be at shutting down glucocorticoid secretion.

there is atrophy of the hippocampus in long-term depression. The atrophy emerges as a result of the depression (rather than precedes it), and the longer the depressive history, the more atrophy and the more memory problems.

certain features dominated as psychologically stressful: a loss of control and of predictability within certain contexts, a loss of outlets for frustration, a loss of sources of support, a perception of life worsening.

“depression is not generalized pessimism, but pessimism specific to the effects of one’s own skilled actions.”

In people with panic attacks, the anxiety boils over with a paralyzing, hyperventilating sense of crisis that causes massive activation of the sympathetic nervous system.

Life consists of the concrete, agitated present of solving a problem that someone else might not even consider to exist.

We have now seen some interesting contrasts between glucocorticoids and the catecholamines (epinephrine and norepinephrine). Chapter 2 emphasized how the former defend you against stressors by handing out guns from the gun locker within seconds, in contrast to glucocorticoids, which defend you by constructing new weapons over the course of minutes to hours.

Or there can be an elaboration of this time course, in which catecholamines mediate the response to a current stressor while glucocorticoids mediate preparation for the next stressor.

Now we’ve gotten somewhere. Being tickled doesn’t feel ticklish until there is an element of surprise. Of unpredictability. Of lack of control.

Pleasurable lack of control is all about transience—it’s not for nothing that roller-coaster rides are three minutes rather than three weeks long.

This is the essence of the downward ratcheting of addiction.

The stranglehold of addiction is when it is no longer the issue of how good the drug feels, but how bad its absence feels. It’s

Many drugs, including alcohol, raise glucocorticoid levels when they are first taken. But with more sustained use, various drugs can blunt the nuts and bolts of the stress-response. Alcohol, for example, has been reported in some cases to decrease the extent of sympathetic nervous system arousal and to dampen CRH-mediated anxiety.

The dynamics of many of these drugs in the body is such that the amount of time that blood levels are rising, with their stress-reducing effects, is shorter than the amount of time that they are dropping. So what’s the solution? Drink, ingest, inhale, shoot up, snort all over again.

More problems for subordinate individuals: elevated resting blood pressure; sluggish cardiovascular response to real stressors; a sluggish recovery; suppressed levels of the good HDL cholesterol; among male subordinates, testosterone levels that are more easily suppressed by stress than in dominant males; fewer circulating white blood cells; and lower circulating levels of something called insulin-like growth factor-I, which helps heal wounds. As should be clear umpteen pages into this book, all these are indices of bodies that are chronically stressed.

What makes for social capital? A community in which there is a lot of volunteerism and numerous organizations that people can join which make them feel like they’re part of something bigger than themselves. Where people don’t lock their doors. Where people in the community would stop kids from vandalizing a car even if they don’t know whose car it is. Where kids don’t try to vandalize cars.

“The more unequal are incomes in a society, the more pronounced will be the disadvantages to its better-off members from public expenditure, and the more resources will those members have [available to them] to mount effective political opposition.”

I discussed the evidence that this could arise from damage to the hippocampus, the part of the brain that (in addition to playing a role in learning and memory) helps inhibit glucocorticoid secretion.

As the most obvious example, physical conditioning brought about by regular exercise will lower blood pressure and resting heart rate and increase lung capacity, just to mention a few of its effects.

It is true that hope, no matter how irrational, can sustain us in the darkest of times. But nothing can break us more effectively than hope given and then taken away capriciously. Manipulating these psychological variables is a powerful but double-edged sword.

Exercise is great to counter stress for a number of reasons. First, it decreases your risk of various metabolic and cardiovascular diseases, and therefore decreases the opportunity for stress to worsen those diseases.

God grant me the serenity to accept the things I cannot change, courage to change the things I can, and wisdom to know the difference.