Demystifying the HPA Axis and Why it is So Integral to Women’s Health
Updated: Sep 26, 2021
This is a topic that comes up in almost every conversation I have with clients and colleagues alike. The Hypothalamic—Pituitary—Adrenal (HPA) axis is so immensely intertwined with all individuals’ (that is, both male and female) health – but it has specific implications for women that need to be highlighted and honed-in on in our practice of care.
Why so important you ask?...
Well, as I am not an expert in neurochemistry (i.e., an endocrinologist or a Ph.D. level neuroscientist), I’m going to spare you a lot of cut-and-paste from the textbooks and instead give you the explanation that I provide to many of my clients – at the 7th-grade level of understanding.
Our brains have these beautifully intricate systems in place to help us manage every single aspect of our daily function – like a really complicated chemistry set! Most of our responses to daily existence (i.e., hunger, thirst, sexual arousal, anger, fear, aggression, fatigue, etc.) can be explained by the combination and strength of the various “cocktails” that these different regions of the brain whip up on any given occasion – yes, your brain is like a bar full of very well trained mixologists (kinda).
The HPA axis – that is, those three brain regions – work more like a team, each region contributing something different, and each triggered by the one preceding it in a perpetual loop. One of the primary jobs of this team is to manage the STRESS response.
Now, when I say "stress," most of us have about a million different things that we could start listing off in our heads that make us feel super stressed out. But I want you to consider this: those are not the things that this system was designed for.
The biological makings of human beings have been evolving for hundreds of thousands of years, with the modern brain of homo sapiens reaching its current status estimated to be somewhere between 100,000 and 35,000-years-ago. In this big picture of time regarding the evolutionary biological process, our most recent 5,000 years of modern civilization is a rather small piece of the puzzle.
It has only been in these recent thousands of years – and VERY recently within the technological boom of our current era – that the things we find ourselves stressed out about in human civilization have ever been relative concerns. No. Rather, the ‘modern brain’ (100,000 - 35,000-year-old version) is still programmed with primitive hardware designed to run from tigers in the jungle or evade a pride of hungry lions on the plains of Africa.
The modern world that we live in today is buzzing and humming with the advances of a technologically capable civilization, which is like a new software program being operated in an old clunky piece of hardware. Our brains, while continually adapting to the world we live in, still are not 100% great at calibrating the chemical response for a stress that is induced by annoying coworkers, traffic jams, late-notices on bills that need to be paid, non-communicative spouses, disobedient children, etc., versus what it was designed to help us manage… evade death by running away from animals with large teeth. Our ‘modern brains’ are still responding like we are living in a primitive world… and we are not.
The type of stress experience in our modern life is a bit more like being trapped continuously in a swarm of gnats. Lots of little, irritating, chronic stressors buzzing around our daily existence. Can you imagine if your fight-or-flight response responded to that swarm of gnats as if you were being chased by a tiger?
For people who live in a state of chronic stress (i.e., a constant swarm of gnats) their nervous systems are doing just that. The HPA axis is seeing a threat, and it’s trying to manage it. It is only a swarm of gnats… but the brain is gearing you up to fight for your life and run like hell. And this is not a good thing. This is how the system becomes chronically dysregulated – because it’s in a constant negative feedback loop.
So how does this relate to women’s health exactly?...
Men and women both experience these stressors of daily life as members of our modern world. While both have been shown to have significant impact of HPA axis dysregulation, the HPA axis in the female brain is reported in the research to have an increased sensitivity to this feedback loop. Female brains process stress differently.
But, more than just being extra sensitive in our neurochemical response to stress, there is another big reason that this has such a dramatic impact on female health and wellness – the HPO axis. The Hypothalamic—Pituitary—Ovarian (HPO) axis is the feedback loop that helps the female regulate her fertility cycles. Men have a similar axis – in fact, in both men and women, the Hypothalamic—Pituitary—Gonadal (HPG) axis is at play… boys have testes, girls have ovaries. So the female version of this HPG axis is – ding ding, you got it – the HPO axis.
And if there is anything we know about the fertility cycles of women versus men… they are quite different. Men have a steady stream of influence from the HPG axis throughout the duration of their life. While contrarily, women are slaves to the rhythms of their HPO axis. During the reproductive years of woman-hood, every very single month, like the tides of the moon, the female fertility cycle waxes and wanes as it prepares for the potential of receiving the necessary building blocks of human life.
Because women are in a constant state of fluctuation – even those using synthetic hormones to disrupt the potential fertility of their cycle – the health and rhythm of the HPA axis directly interacts with the health and rhythm of the HPO axis. As the first two letters indicate, they are two-thirds comprised of the same brain regions.
When chronic stress has the HPA axis on a negative feedback loop, it wreaks havoc upon the HPO axis as well… throwing off the entire biorhythm of our female brain, female body, and the lived experience of our female lives.
And that (I would say) is some important information in addressing the big picture of women’s health.
Want to understand this concept in more detail? I quite like how Courtney K. Pickworth articulates the ‘pregnenolone steal’ in her segment on ‘Women’s Health and Hormonal Axes.’ She also goes on to explain how essential ‘lifestyle support’ is in order to promote healthy hormones – ding ding ding!! This is what OTs do and do so well!!
1. Focus on stress management.
2. Exercise regularly.
3. Get enough sleep and pay attention to sleep quality.
4. Avoid processed foods and body products with synthetic ingredients.
These are ALL aspects of occupational identity – with a strong leaning in the occupation of ‘Health Management.’ Have you read the newly published Occupational Therapy Practice Framework: Domain and Process [4th edition] yet? This is a big addition, folks. OTs have a LOT to offer here in the domain of women’s health.
A small side note:
It is certainly worth mentioning that not ALL individuals (or all women) process the stressors in their life equally. And while the term 'stress' and it's accompanied hormone side-kick cortisol are oft vilified in the health literature, it is important to acknowledge that cortisol has positive benefits too (i.e., helping to control blood sugar levels, regulate metabolism, aide in the reduction of inflammation, and assist with memory formation). Allowing and challenging the body to process healthy, manageable levels of cortisol has positive outcomes on building adaptability and resilience in these neural networks. And some people just manage this adaptation better than others.
Additionally, even when traumatic stress is introduced to the developing circuitry of the HPA axis, as studies on infant development have shown, as many as one-in-five neonates simply responds better to these typical neurologically dysregulating instances. The scientific community is still piecing together what makes these outliers so much more resilient.
About the author:
Heather M. Truog, OTD is an American occupational therapist with over a decade of clinical experience working with trauma recovery, neuromuscular dysfunction, and women’s health topics. She founded The Women’s Health OT as a culminating project for a post-professional doctorate in occupational therapy. She continues to use this platform to advocate for the role of the occupational therapist in the practice area of women’s health, to promote growth in this specialty niche among fellow OTs and OT students, and to fill gaps in the knowledge that OTs experience when seeking out information to piece together their conceptualization of evidence-based practice.
Feel free to contact Heather directly if you have questions, insights, or are looking for someone to volley ideas with relative to the practice area of women’s health: firstname.lastname@example.org
Altemus, M., Sarvaiya, N., & Epperson, C. N. (2014). Sex differences in anxiety and depression clinical perspectives. Front Neuroendocrinolog. 35(3): 320–330. Doi:10.1016/j.yfrne.2014.05.004.
Dayan, J., Rauchs, G., & Guillery-Girard, B. (2016). Rhythms dysregulation: A new perspective for understanding PTSD? Journal of Physiology. 453–460
Donner, N. C. & Lowry, C. A. (2013). Sex differences in anxiety and emotional behavior. Pflugers Arch. 465(5): 601–626. Doi:10.1007/s00424-013-1271-7.
McKay, S. (2019). The Women's Brain Book. Hachette Australia: Sydney, NSW.
Neubauer, S., Jublin, J. J., & Gunz, P. (2018). The evolution of the modern human brain shape. Science Advances. Vol 4. No. 1. Doi: 10.1126/sciadv.aao5961
Robers, A. G. & Lopez-Duran, N. L. (2019). Developmental influences on stress response systems: Implications for psychopathology vulnerability in adolescence. Comprehensive Psychiatry. 88, 9–21