Stress, Anxiety and the Human Brain
Because stress and anxiety can take so many forms and have so many triggers, brain reactions to it vary a lot.
Fortunately, neuroscientists have made tremendous progress in the last few decades toward revealing the underlying neural circuitry of these problems.
When stress and anxiety escalates to a level that impairs daily function, there is an imbalance of specific brain messengers, called neurotransmitters such as gamma-aminobutyric acid (GABA), dopamine, and epinephrine.
One important neurotransmitter, serotonin, is essential for feelings of well-being.
When serotonin declines, it causes feelings of anxiety and depression. In conditions such as PTSD and panic disorder, the stress hormone cortisol surges, increasing feelings of fear and dread.
Several different brain regions control anxiety responses. The amygdalae, almond shaped areas deep beneath the temples in the brain’s temporal lobes, control emotions.
Anxious people often have hypersensitive amygdalae. When facing unfamiliar situations, they may experience exaggerated stress that results in physical symptoms (rapid heart rate, increased blood pressure) and exaggerated emotional reactions.
Near the amygdalae is the hippocampus, which converts experiences into long-term memories.
Unfortunately, such memories can lead to heightened sensitivities to circumstances and situations, and set off the amygdala’s anxiety response in the future.
Another brain region activated by anxiety is the frontal lobe, also called the “thinking brain.” This part of the brain processes uncomfortable emotions and attempts to put them into perspective.
Chronic or even intermittent stress can cause wear and tear on the brain regions that control our responses.
For example, research indicates that the hippocampus is actually smaller in people who were abused as children or were in military combat.
Regardless of the form of anxiety, when a person perceives danger his or her body triggers the sympathetic nervous system, which sets off a fight-or-flight response that involves the release of adrenaline and other stress hormones.
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