2018 Dec 18 —HOW STRESS HARMS THE BRAIN
From an engineering standpoint, stress can be defined as the amount of resistance a material offers to being reshaped and reformed. When you place a load on a steel beam, the beam resists, keeping the building from collapsing. If the load is great enough, the beam gives way and the structure suffers damage or collapses. Psychological stress is similar. When we can no longer resist forces that are trying to shape and mold us, whether they are our spouse’s behavior or our nation’s economic decline, we break down, becoming anxious and depressed, unable to cope.
Sources of stress are everywhere. The rate of technological change has never been as accelerated as it is today. College students are training for jobs that don’t yet exist. Americans in the workforce today can expect to go through at least three career changes during their professional lives. Even thinking about this is stressful.
Psychologists identify two kinds of stress: acute and chronic. Both affect the health of mitochondria in our cells and our general well-being. Acute stress is relatively short-lived. It’s what you encounter when faced with a novel learning situation, and it is actually good for you in the sense that it allows you to remember the event, be it positive or negative. Chronic stress is long-lasting. It occurs when you worry all month about how you’re going to make your mortgage payment, or when you dread every day waking up next to the person you married many years earlier, or when your cells are continuously burdened with eliminating toxic wastes and heavy metals acquired from a polluted environment and now stored within the cell wall.
Unlike acute stress, which serves a positive purpose, chronic stress is very destructive. In Colonial times the legendary pirates of the Caribbean learned that citizens in a city under siege were more effectively worn down by the sound of cannons firing than by the actual damage done to their town by the cannonballs. This was because the sounds of the guns kept the townspeople in a state of chronic stress, unable to fight or flee, or get a good night’s rest. Long-term exposure to stress has profound consequences.
Chronic stress can lead to a rut in which the wiring of our neural networks keeps us repeating the same dysfunctional behavior and hoping for a different outcome. As we experience depression and repetitive behaviors that stem from chronic stress, we’re less capable of analytic thought. The stress hormones released into the bloodstream—mainly adrenaline and cortisol—keep us at a lower order of brain function, unable to attain synergy. We find it increasingly difficult to learn from past experiences, to alter the beliefs that cause us to re-create those experiences again and again, and to break out of our behavioral ruts. Because of the way our brains have been wired by stress and trauma, we’re unable to think or feel our way out of personal crises.
Dr. Robert M. Sapolsky, in his book Stress, the Aging Brain, and the Mechanisms of Neuron Death, eloquently describes the science that correlates stress, exposure to cortisol, and the ultimate destruction of the hippocampus. His extensive research with rodents and primates clearly supports the contention that this stress-induced neuro-degenerative process also occurs in humans. Interestingly, Sapolsky points out that elevated cortisol levels are found in at least 50 percent of Alzheimer’s patients.
Fortunately, we can stop this cascade of destructive chemical events. Research has shown that elevated levels of brain-derived neurotrophic factor (BDNF) imparts a high level of protection for the hippocampus, making it resistant to damage from elevated cortisol.