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How chronic stress affects the brain

Chronic stress can have a detrimental effect on the brain and the body. This is because of the way our brain has developed and is structured. Humans developed certain characteristics to enable them to stay safe, stay alive, and to thrive in prehistoric times. The mind prepared the body for two key stages – fight and flight and rest and digest driven primarily through the distribution of stress hormones.

As Rick Hanson says in his book ‘Buddha Brain’ “Suffering is not abstract or conceptual. It’s embodied you feel it your body, and it proceeds through bodily mechanisms.” It’s important to understand that the mind affects the body and that suffering cascades through the body via the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal axis (HPPA). Chronic activation of the HPPA places an individual into a heightened state of anxiety which can have a series of ill effects in the body. It can also affect mood, relationships and indeed impact almost every part of life.

The mind and chronic stress

The mind is complex and responds to perceived threat (like chronic stress) in the same way as if it is a physical threat (from a tiger) or a deadline or arguments at work or at home. The amygdala raises the ‘alarm’ which triggers the thalamus to ‘wake-up’ releasing norepinephrine in the brain. The SNS alerts the major body organs to be ready to fight or flight. The hypothalamus signals to the pituitary gland, which in turn alerts the adrenal glands to release the stress hormones adrenaline and cortisol.

The results are almost instantaneous. The heart rate and blood pressure increase, pupils dilate and blood is moves to the major organs stimulated by norepinephrine. Lungs dilate and breath quickens. Cortisol suppresses the immune system but also causes the brain stem to trigger the amygdala which increases the SNS/HPAA system, and more cortisol is releases. Cortisol suppresses the hippocampus (which normal calms the amygdala) and more cortisol is released.

The body’s response to chronic stress

The body is in a heightened state of awareness and stimulations. Emotions intensify. A heightened state of emotion can in turn stimulate the amygdala once again – which means more cortisol and this continues. As the limbic and endocrine activity continues at this pace, the pre-frontal cortex activity declines, which means that reason and balance tend to decrease. The brain also focusses more on negative things and thoughts (to protect it from attack).

Many people in modern society live in this permanent state of arousal/stimulation. It has its place, but in the long term it leads to the physical issues mentioned above. It also leads to the amygdala becoming sensitized. More problematic is that this can become a learned pattern of behaviour for the brain. The amygdala helps form implicit memories, and as it becomes more sensitized, these are tainted with fear which intensifies trait anxiety.

Frequent activation of the SNS/HPAA can reduce the number of new neurons being produced. Painful experiences can be recorded in implicit memory and cause imbalances in mood, dissociation, and increase emotional responses. Over time it can cause problems with the production of serotonin and dopamine.

This perpetual cycle can become ingrained in a person’s life where they live in a heightened state of anxiety and can feel like there is no way out because they don’t always understand the science behind what’s happening. Even when they understand the scientific reasoning it can be hard to see beyond that. It’s important to let people know that its ‘not their fault’ and there are techniques that can help restore balance, perspective and harmony.

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