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Last week I gave you an introduction to stress, how to identify it and what causes it. This week I will be focusing on the different responses of the body to acute (short-term) and chronic (long-term) stress.

Imagine the following scenario: You are visiting a lion park, and one of their lionesses accidentally escapes their cage. Unfortunately, you are not in a car, as you are allowed to walk around among the cages. You are now being chased by the lioness. The best way to understand the effect of acute stress is to visualise yourself in this situation.



First and foremost, when seeing the lioness outside the cage, a part of the brain called the HPA axis (hypothalamic-pituitary-adrenal axis) is activated. What is the HPA? To simplify, the HPA axis is basically our central stress response system.

The central stress response system then triggers the production and release of steroid hormones (glucocorticoids), including the primary stress hormone, cortisol. Cortisol is important in the organising systems throughout the body (including heart, lungs, circulatory system, metabolism, immune system and skin) to deal with the lioness as quickly as possible.

The central stress response system also releases certain well-known chemical messengers, namely dopamine, norepinephrine and epinephrine (also known as adrenaline). These chemical messengers then activate an area inside the brain called the amygdala, which in response triggers an emotional response to a stressful event. In the case of the lioness, this emotion is likely fear.

The brain then releases a small protein (neuropeptide S) that regulates stress by decreasing sleep and increasing alertness and a sense of anxiety. This gives you a sense of urgency to run away from the lioness.

During a stressful event, activity in areas at the front of the brain, connected to short-term memory, concentration, inhibition and rational thought, might become suppressed. This series of events allows you to react quickly by either fighting the lioness or fleeing from it.

During this time, chemical messengers are also sent to the hippocampus to store this emotional experience in long-term memory. This is essential as this action is critical for survival and the brain will therefore try and avoid such threats in the future.


Below are 11 ways chronic stress affects your brain health:

  • Stress creates free radicals that kill brain cells.
  • Chronic stress might make you forgetful and emotional.
  • Stress creates a vicious cycle of fear and anxiety.
  • Stress halts the production of new brain cells.
  • Stress depletes critical brain chemicals, causing depression.
  • Stress puts you at greater risk for mental illnesses of all kinds.
  • Chronic stress shrinks your brain.
  • Stress allows toxins into your brain.
  • Chronic stress increases your risk of dementia and Alzheimer’s disease.
  • Stress causes brain cells to commit suicide.
  • Chronic stress contributes to brain inflammation and depression.

That about covers the effects of acute and chronic stress on the brain. Next week we will be looking at the response from the heart, lungs and circulatory system, as well as the immune system’s response to acute stress.

Until next week,
Stay stress-free!

Author’s note:
All information in this blog was researched for this blog, and is not intended for self-diagnosis or to be used as medical advice. All medical questions should be directed to a healthcare professional such as a doctor or pharmacist.

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