What is the HPA axis, and why is it important?

The HPA axis is the hypothalamic-pituitary-adrenal axis, a complex network of neurological feedback loops that maintain balance by regulating our stress response.

It connects the central nervous system and the endocrine system via 3 organs:

• Hypothalamus- a region of the brain which detects stress and releases corticotropin-releasing hormone (CRH) upon encountering a stressful event.
• Pituitary- a pea sized gland in the brain which receives CRH signals from the hypothalamus, then secretes adrenocorticotropic hormone (ACTH).
• Adrenals- a pair of glands located above the kidneys which are stimulated by ACTH and release stress hormones such as cortisol.

Collectively, the HPA axis helps us respond to our environment and any stressors that we encounter.

The physiological effects of stress

Cortisol is our primary stress hormone. When cortisol is released, it starts a cascade of biological responses so that we can deal with the threat at hand. Some of these responses include: increased heart rate, increased blood flow to the extremities, increased blood glucose and sharper vision.

It is both normal and healthy to have increased cortisol when encountering a real life stressor so that we can respond appropriately to the threat at hand. The classic example is that of encountering a wild bear. The physiological responses from increased cortisol would help us deal with the stressor at hand (fight or fly), and in an ideal situation, our cortisol levels would return to normal once the bear (or stressor) is gone.

Unfortunately, bouncing back once a stressor has disappeared is not always simple. Humans are more susceptible than other animals to the effects of stress as we have the ability to imagine stressors which are not actually present in our environment. This leads to continued physiological stress responses even when we are not faced with true stress in our immediate environment. In modern times, our stressors can range from work tasks, interpersonal relationships, financial strains and so on, many of which are continuously imagined in the background of our daily lives. This makes it impossible to shake off the stress as we would have once the bear disappeared, leading to pathological stress.

Pathological stress

The HPA axis enters a state of dysfunction in the presence of chronic ongoing stress (both real or imagined), beyond what would be a “normal” duration. If the stressor (real or imagined) is not dealt with, the extended release of cortisol creates a state of chronic inflammation, whereby the body may become resistant to the effect of cortisol, or drastically reduce its production over time, leading to a state of weakness, tiredness, and an overall feeling of inability to cope. This is known as HPA axis dysfunction, or colloquially, burnout.

Signs and symptoms you may have HPA axis dysfunction

The signs and symptoms of HPA axis dysfunction can vary depending on the stage of dysfunction.

Early signs of HPA axis dysfunction include: heightened awareness, increased body temperature, difficulty falling asleep, racing thoughts, difficulty switching off.

Advanced signs HPA axis dysfunction include: chronic fatigue, brain fog, low motivation, poor mood, weariness and deflation. 

HPA axis dysfunction is best managed as soon as possible as extended stress can increase the risk of a number of serious conditions such as anxiety, depression, weight gain, cardiovascular conditions and insomnia.

Eliminating stress from modern life is an unlikely endeavour, so adopting appropriate dietary, lifestyle and psychological strategies to manage stress and its consequences is imperative. Supplements which help manage the physiological stress response may also be helpful to avoid entering the burn out stage of stress. Various herbal medicines such as holy basil, withania, Siberian ginseng, rehmannia and rhodiola have a long history of traditional use for managing stress, supporting endurance and reducing fatigue. Certain nutrients such as magnesium, B vitamins, zinc and vitamin C can also support a healthy stress response.

Reach out to your BioMedica practitioner to discuss methods to manage stress and to confirm if supplements are appropriate for you.

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