Time to Read: 10 minutes
Stress – we all know it, in fact – we all feel it. Stress is at an epidemic level worldwide, and an increasing body of research is showing the harmful impacts stress has on our physical and mental health. We probably don’t need a bunch of scientists to tell us that, either. We can feel the impacts of stress on our bodies and it certainly doesn’t feel good! But what is stress? Where does stress come from in the brain? And what does stress do to your body?
This article we will take a closer look at the Hypothalamic-Pituitary-Adrenal Axis, or ‘HPA axis’ if you don’t want to get your tongue twisted. The HPA Axis is our primary stress response, its main purpose is to mobilise our body into action during a stressful or threatening event, but sometimes things can get a little bit haywire when our HPA axis has become dysregulated.
The science of stress
Let’s break down the main structures involved in stress:
- Hypothalamus: a structure deep within the brain that is responsible for sending messages to other areas of the brain to keep the body in balance (homeostasis). It’s basically the middle management of the brain – receives a message and directs other structures to do their job to help the overall organism.
- Pituitary Gland: A pea-sized gland located just below the hypothalamus, it’s small yet incredibly powerful – it’s the pocket rocket of the brain! The pituitary gland produces and releases many different hormones responsible for an array of bodily functions including metabolism, growth, sexual maturation, reproduction, blood pressure, stress, and many more functions.
- Adrenal Glands: Small glands attached to the top of each kidney, these glands produce hormones that help to regulate many essential functions of the body such as blood pressure, immune system, metabolism, sex, and most famously known for its response to stress.
What is the Hypothalamic Pituitary Adrenal Axis?
Now we know the basics, let’s put it all together. Imagine for a moment that you’re standing in front of hundreds of people about to make an important speech (Eek! even the thought of this stresses me out!). You walk onto the stage and gaze out to the audience to see hundreds of eyes all on you. Within your body, your HPA axis is gearing up to protect you from this perceived threat.
Initially, when an external stressor occurs, your sympathetic nervous system activates, which is a network of nerves that trigger physiological changes within your body to energise you to run away or fight the perceived threat. Seconds after the activation of the sympathetic nervous system, it’s the HPA axis’ time to shine. The hypothalamus receives a signal that your body is under threat, and in response releases a hormone called the corticotrophin-releasing hormone (CRH). The release of the CRH further increases the activity of the sympathetic nervous system and sends a message to the pituitary gland to pump out some adrenocorticotropic hormone (ACTH), which is directed down to the adrenal glands. ACTH binds to receptors on the adrenal glands, and in response, adrenal glands release a hormone called cortisol into the bloodstream. Cortisol is the primary stress hormone and is responsible for mobilising the body into action.
You walk onto the daunting stage, you’re standing in front of hundreds of people, your HPA axis has been activated – cortisol is released and is helping your body mobilise itself to get the heck out of that scary situation! Of course, you probably shouldn’t run away, I’m sure your speech is very worthwhile to present. The stress response is great for situations where you are physically under threat, like, being swooped by a magpie (been there- I do not recommend that experience!) where you really do need the cortisol to help you run away. But what about situations where the cortisol really isn’t helping anyone? How do we help our body to regulate?
Luckily the HPA axis has an inbuilt system where it reverses its circuitry to down-regulate itself back into a calm state. This happens when cortisol reaches a certain blood concentration, the hypothalamus detects this, sends a message to the pituitary gland which shoots a message down to the adrenal glands, and all is calm again. We are also able to do this via brain training (read more about this here)
However, sometimes the HPA axis is dysregulated, and its ability to down-regulate has been hindered. Cortisol becomes too high, and the brain has not learned the appropriate wiring to down-regulate itself when this occurs. This dysregulation normally occurs during the development of the HPA axis.
Development of the HPA Axis – the importance of nurture for infancy brain development
Infancy is a critical period of development for the architecture of the HPA axis, in fact, the HPA axis is still under construction during this time, so how do babies’ HPA axis’ respond to stress? The short answer is through attentive loving care. When an infant is experiencing stress, their sympathetic nervous system kicks in – their heart rate increases, they cry, because well – they can’t run away, they need to alert their caregiver by communicating. Just like in adults, the hypothalamus releases CRH, which sends a message to the pituitary gland to release ACTH and direct it down to the adrenal glands. The adrenal glands pump out cortisol. This is where it gets interesting, baby’s brains and bodies are still learning how to create equilibrium in the stress response, so they depend on a caregiver to down-regulate their HPA axis circuitry.
In a perfect world baby cries > stress response is triggered > caregiver provides care > this care triggers release of oxytocin > oxytocin inhibits the cortisol and triggers the down-regulation of the HPA axis > baby returns to homeostasis.
This attentive care and production of oxytocin in response to stress is what quite literally scaffolds the development of the HPA axis, so that later in life when the baby grows, they will have the capacity to self-regulate and respond to stress healthily.
When the HPA Axis is Under-developed
The harsh reality is that not all babies receive this attentive care, and to make things a bit more complicated, the brain is totally complex and the HPA axis’ development is influenced by a whole array of things. Genetics can play a crucial role. A dysregulated HPA axis’ can be passed down through the generations, forming a part of intergenerational trauma.
When the HPA axis is underdeveloped, the brain and body are impacted in their ability to respond to stressful stimuli. Studies have also shown that a dysregulated HPA axis can lead to chronic health conditions such as:
- Psychiatric conditions such as anxiety, depression, and more susceptibility to developing PTSD from stressful stimuli
- Cardiovascular disease
- Immune dysfunction
- Chronic fatigue syndrome
- Sleep disorders
- Thyroid dysfunction
Many people wonder if stress can make you sick, evidently, the answer is yes it can. the HPA axis is crucial to the body’s overall functioning. When the HPA axis is dysregulated, not only does our stress response become heightened, but our mental and physical health are at greater risk too.
How to Regulate a Dysregulated HPA Axis?
Maybe you’re reading this and reflecting on your own HPA axis, you’re wondering if yours is dysregulated. You’ve just read the list of risks that accompany a dysregulated HPA axis, and now you’re stressing about stress! Well, I’m here to tell you that there is hope thanks to our brains’ ability to rewire itself. Neuroplasticity is the brain’s ability to grow and adapt itself to different experiences. The brain has critical windows of development that are sensitive to the development of structures of the brain, such as the HPA axis during infancy, but outside of those windows of development, growth and change are still able to be achieved, it just takes a little bit more work.
If you have a dysregulated HPA axis, your neural pathways have built themselves around this dysregulation, so how do we make new ones? The first and most important thing is to engage in activities that decrease that extra cortisol floating around. Secondly, remember how the release of oxytocin from attentive caregiving nurtured the development of the HPA axis in infancy? This may just be the answer to rewiring the HPA axis. In fact, studies have shown that intranasal administration of synthetic oxytocin can help prevent PTSD by regulating the HPA axis, and what’s more – reducing physical damage to the brain caused by abnormal levels of cortisol. Now, I’m not recommending we all snort some oxytocin to help our brains deal with stress – there are many easier (and safer) ways to produce oxytocin and rewire your HPA axis:
Improving your coping skills through psychotherapy is paramount in improving your HPA axis dysfunction. Through therapy, you can start building new neural pathways to alter your cognitive appraisal when you’re under stress and find healthier coping strategies. Psychological therapy has been demonstrated to foster a biological change within the HPA axis to assist in its regulation.
It’s important that you find a therapist that you click with, it doesn’t matter if you need to go through five, ten or twenty different therapists until you find the right one. The therapeutic relationship is foundational to achieving successful therapeutic outcomes. Creating a safe, trusting, and supportive relationship with your therapist not only assists in feeling open and receptive to learning new coping skills, but the biological underpinnings of the therapeutic relationship are built through oxytocin. It makes sense since oxytocin is what underpins social bonding, too. So not only are you learning new coping mechanisms and altering your HPA axis, but the oxytocin may additionally help in downregulating that cortisol as well.
- Reducing physiological stress
Incorporating relaxation techniques into your daily routine is not only a way to nurture and give yourself some well-deserved self-compassion, but you will also be actively regulating your HPA axis, too! It’s important to find a technique that you personally enjoy because this will increase the likelihood that you will stick with it every day and pave that new neural pathway. Here are a few techniques that have been shown to assist in HPA axis regulation:
I know, I know – everybody recommends meditation and maybe it’s the very last thing you want to do with your precious time. I mean, sitting still and thinking about NOTHING?! But stick with me, studies have found that daily meditation successfully relieves stress and regulates the HPA axis. And thankfully there are so many different styles of meditation to try, it’s not all just sitting on a yoga mat and clearing your mind! Maybe you could try a guided meditation, there are many free guided meditations available on YouTube that you could try.
If stillness is not your thing, there are other ways to meditate, too. Walking meditation is a great way to get all the benefits of meditation without the need to be still! But you need to make sure you are intentional about your walk – bring your awareness to your bodily sensations as you walk; each foot taking a step, how the ground feels under your feet, the breeze on your face, the feeling of the sunshine, your breath. Be mindful and intentional about your walking meditation.
Sometimes we don’t know how much stress and tension we hold in our bodies until we stretch it out and feel the relief that comes. Don’t worry, you don’t need to be a total yogi master to get involved in yoga, stretch as much as your body will allow – we all have different bodies and that is ok! Studies have demonstrated yoga’s ability to support physical well-being, but also mental well-being, too. Yoga can decrease cortisol levels and influence the sympathetic nervous system, and HPA axis regulation. Isn’t that amazing?! And, if you don’t feel comfortable joining your local yoga class, you can try it in your own home. Jump onto Google and start searching for a yoga video that you enjoy. There are so many out there!
- Aerobic exercise
Yes, I know – I, too, roll my eyes at the perked-up people that get a kick from an early morning run, but unfortunately, they may be onto something. Now, I’m not suggesting you get kitted out in running gear and sign up for an ultra-marathon, but studies have shown that high-intensity exercise for as little as thirty minutes a day can help to regulate your HPA axis.
When you participate in high-intensity exercise your body releases cortisol to provide enough energy to your muscles. You might be thinking – MORE cortisol?! That’s the very last thing I need! Well, interestingly, studies have shown that the cortisol released from exercising suppresses the release of cortisol during other stressors in daily life. In other words, exercise gives your body a channel to release cortisol in a healthy manner, which creates a down-regulation of the HPA axis when you are not running.
- Build a social network
There is a psychological phenomenon known as ‘social buffering’ which suggests that social relationships assist in buffering the impacts of stress on the brain and body. This makes sense when you consider that oxytocin is the social bonding hormone and is a cortisol inhibitor! So, when stress occurs but you have a solid support network around you, the oxytocin developed from these relationships will decrease cortisol, further helping your HPA axis to regulate. Social networks don’t need to be a huge amount of people, one or two trusting friends is enough to give your brain and body the stress-buffering benefits!
Start building a community that supports your nervous system – your people are out there. And if you already have a strong support network around you, try to practice reaching out when you are starting to feel stressed – it takes practice, but the more you do it, the more you build a new neural pathway and the easier it gets. I know it seems daunting when you’re only just starting out, but you can do this. Start with just one self-nurturing technique to incorporate into your routine and go easy and start slowly, the benefits are worth it, I promise!
You can do this!
I’m a strong believer in love being the glue that holds humanity together, and it seems that our brains may be held together in the same way. The HPA axis is the powerful driving force behind our stress response, and when its under-developed, a dysfunctional HPA axis puts us at greater risk of chronic health conditions. Attentive care during infancy produces oxytocin to inhibit cortisol – our stress hormone, and this process fosters the healthy development of the HPA axis. Through neuroplasticity, there is hope in regulating the HPA axis when it has previously been dysfunctional. This can be achieved through engaging in activities that reduce cortisol and increase oxytocin.
As American Psychologist, Louis Cozolino, once said “We are not the survival of the fittest, we are the survival of the nurtured.” So, get that oxytocin flowing – give yourself some self-compassion and nurture, you’ll be helping your stress response and overall health and well-being in the process!