How Does Stress Affect the Brain

Profile of Brain

It seems human beings are under chronic stress these days. Stress, which is a biological imperative stemming from the fight or flight response that protected early humans from predators, has profound physiological effects on the entire body, including your brain. Even low levels of stress may cause significant changes in your brain over time.

Stress Shrinks Your Brain

A 2012 Yale University study showed that chronic stress can actually reduce brain volume. In other words, if you are stressed out all the time, your brain just might shrink. Among its many effects, lower brain volume can lead to impaired cognition and hampered emotional function.

Why does this happen? According to the study, stress and/or depression activate a transcription factor known as GATA1, which regulates the genes that control synaptic connections. When fewer synaptic connections form, brain volume is lowered.

The good news is damage doesn't have to be permanent, however. Brain volume can return to normal, according to the author of a 2000 brain volume study of people with post-traumatic stress disorder. When hormone levels in the brain return to normal, brain volume rebounds to normal size.

Stress Kills Brain Cells

Stress can also kill brain cells, particularly in the areas associated with memory and learning, according to the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, Rockefeller University. When your brain perceives stress, your body releases adrenalin into the bloodstream, giving your brain the burst of energy it needs to fight, flee, or freeze.

After about one minute, the adrenalin leaves your brain and it returns to normal function. If the threat persists or is severe, your brain calls in the big guns. According to Stanford University brain researcher, Robert M. Sapolsky, these are a class of steroidal hormones, called glucocorticoids. You may have heard of cortisol, which is one example of a glucocorticoid. These hormones remain in your brain, and continue to impact its functioning, far longer than adrenalin.

Both types of hormones head straight for the hippocampus. Your body requires a state of homeostasis (hormonal balance) to function properly. The balance between sympathetic and parasympathetic hormones is very delicate. Chronic stress can keep these hormones unbalanced. High levels of either type of hormones can kill cells in the hippocampus, hampering memory and learning.

Stress Hinders Cognition, Expression, and Memory

According to the University of Maryland Medical Center, stressful events activate the hypothalamic-pituitary-adrenal system, which release catecholamines - neurotransmitters such as dopamine, norepinephrine, and epinephrine. These chemicals activate the amygdala and suppress concentration, short-term memory, rational thought, and inhibition.

This suppression of normal brain responses allows you to engage fully in fight or flight without your brain intruding. Unfortunately, suppression of such responses over the long-term can also harm your memory and impair cognitive function.

Stress Depletes Brain Chemicals

If a threat is especially severe or recurs frequently, such as protracted combat or living with abuse, the chemicals that carry messages from one nerve cell to another become depleted, and the brain becomes sluggish and inefficient. According to the American Institute of Stress, this can lead to a variety of mental health effects, including:

  • Depression
  • Sleep disturbances
  • Racing thoughts and difficulty concentrating
  • Difficulty learning
  • Absent-mindedness
  • Difficulty making decisions
  • Obsessive or compulsive behaviors
  • Increased hostility, worry and guilt

Stress Surpasses Logical Thinking

A man heroically rushes into a burning building to save a child, and afterwards says he "just reacted" or "went on auto-pilot." The HeartMath Solution, based largely on the research of Dr. Daniel Goleman, and presented at the 12th Annual Unified Program Conference, outlines what likely motivated the hero's actions.

He experienced extreme stress at seeing the child in imminent danger, and that information entered his brain with such force and urgency that it bypassed the prefrontal cortex and other higher brain centers. It went directly into the limbic system, which is the seat of emotion and reaction. Essentially his reason and judgment went off-line temporarily, and he reacted from the reptilian center of his brain, located in the brain stem. This is also the part of the brain that controls heartbeats, breathing and other autonomous bodily functions.

Interestingly enough, this is the same mental process that occurs during a crime of passion. When incoming perceptions bypass the rational part of the brain, a person may act without the regulating effect of wisdom, memory or judgment. Logic is simply unavailable in the moment, and reactions are based on raw emotion.

Stress Shuts Down Functions and Sharpens Others

Have you ever encountered extreme stress and suddenly engaged in very instinctual behaviors? This happens because adrenaline causes the brain to start and stop certain functions in order to effectively deal with the perceived threat triggered by stress. According to the Franklin Institute, adrenaline will start and stop the following brain functions while it is present:

  • It causes the brain to signal the release of glucose and fatty acids into the bloodstream in order to provide instant energy and strength.
  • It sharpens your senses in order to perceive further threats.
  • It makes you less sensitive to pain so you can continue your fight or flight.
  • It shuts down functions unnecessary for either fight or flight, including growth, reproduction, or immunity.
  • It instructs the brain to reduce blood flow to the skin.

Stress Compromises the Blood-Brain Barrier

The blood-brain barrier protects your brain and central nervous system from viruses, drugs and chemicals that enter your bloodstream. Multiple studies, including one printed in the British Medical Journal suggest that extreme stress compromises the blood-brain barrier, making it more permeable. This makes the brain more susceptible to infection and dangerous changes in brain chemistry.

If certain chemicals can easily permeate the blood-brain barrier, you may be more susceptible to nerve damage or even brain damage.

Gender Differences

Men and women may respond to stress differently. According to the National Institute of Mental Health, women's stress hormone receptors are less adaptive than men's, so women may be more likely to experience stress related mental disorders like post-traumatic stress disorder (PTSD) or depression than their male counterparts.

Minimizing Negative Effects

The news isn't all bad, according to Rockefeller University's Bruce McEwen, Ph.D. The brain's short-term response to stress is actually protective. However, over the long-term, stress can cause damage.

You can, however, take steps to reduce chronic stress levels and protect your brain. Engaging in stress-reduction techniques like meditation and regular exercise can help, as can maintaining a supportive social network. If chronic stress is a part of your life, try to find ways to minimize your stress load.

Managing Stress

In his book, Why God Won't Go Away: Brain Science and the Biology of Belief, Andrew Newberg offers insights on how to manage stress:

  • Relax and focus
  • Breathe deeply
  • Pray or meditate
  • Do something that pleases you, whether it's listening to a child's laughter, going fishing or taking a bath

Newberg performed experiments with Tibetan Monks who meditate and Catholic Nuns who pray. He discovered that members of both groups exhibit reduced stress levels and enhanced brain function over those who do not routinely pray or meditate.

Healing Your Brain

Strategies to facilitate healing include:

  • Protect your brain by learning effective stress management techniques.
  • Feed your brain. It is best able to withstand challenges when you eat a well-balanced diet.
  • Kill the ANTS (automatic negative thoughts). Too many of those can trigger glucocorticoids.
  • Exercise your body to boost your brain. Physical activity pushes blood and fuel into your brain, which helps you to reduce stress and improve memory.
  • Visit your doctor early if you think you may have a brain problem.

Take Care of Yourself

Understanding stress and its effects on your brain can help you protect yourself. In a very busy world where stress is the norm rather than the exception, it's important you seek to mitigate stress using any technique that works for you. Your brain manages all of your bodily functions, so it's important you protect it.

How Does Stress Affect the Brain