The Human Stress Response System- HPA-Axis a.k.a. The Human “Danger Brain”
By: Eve Coberly, M.S., M.A.
Reviewed: Zack Butterfield, CMHC, BCN
The human body is an amazing biological machine made up of not one, but many different body systems. For instance, the human body has a digestive system that breaks down food into energy, a muscular system that helps coordinate movement, and a respiratory system that pumps oxygen throughout the body. Although all of these systems serve different functions, miraculously they end up working harmoniously together helping us do the things we do everyday.
One body system that we are all intimately familiar with that is vital to our everyday life is our stress response system; what is known in the scientific world as the “hypothalamic–pituitary–adrenal-axis”/“HPA-Axis” (Snipes, 2019; ). The HPA axis is located above the brainstem, and is part of the sympathetic nervous system, which is a subsystem of the body’s autonomic nervous system (ANS) (Torrezan et al. 2018; Rotenburg & Magrath, 2017). The overall job of the ANS is to regulate a variety of automatic/unconscious bodily processes, such as breathing, digestion, heart rate, blood pressure, stress response, and other important automatic functions. (Snipes, 2019; Torrezan et al., 2018; Perrin et al., 2019; Rotenburg & Magrath, 2017).
Although most animals have a brain that is connected to a stress response system, the human brain is unique in that it has a newer evolved part called a prefrontal cortex (World Science Festival, 2019). The prefrontal cortex is located in the front part of the brain, and gives humans executive functions like higher order thinking, planning, and behavioral control (Broderick & Blewitt, 2020; World Science Festival, 2019). Although the human brain has this more evolved part, like other animals, it still has retained some of its more primitive parts like its HPA-axis or what can simply be identified as a person’s “danger brain”. It is no accident that humans still have their danger brain, because without it, humans could no longer adequately protect themselves from threat or danger (Snipes, 2019).
The Human Stress Response System-HPA-Axis: A Delicate Dance of Chemicals & Hormones
Given that the danger brain is vital to a human’s day-to-day survival, let’s take a closer look at how this delicate yet powerful system works.
Pretend that you are out camping in the woods, and suddenly hear something rustling in the trees behind you. Your ears pick up on loud crackling noises and your nose smells something musty. In lightening speed, this outside sensory information, coming in from your ears, goes straight to your autonomic nervous system, which in turn, triggers your HPA axis a.k.a. your “danger brain”. One of the first hormones released from the danger brain is cortisol. Cortisol is the body’s main “go-to” stress hormone (Rotenburg & Magrath, 2017; Doc Snipes, 2020). The main purpose of cortisol is to increase the amount of sugar in the blood so a person has plenty of energy to ward off stress and danger (Doc Snipes, 2020; Doc Snipes 2017; Rotenburg & Magrath, 2017). Cortisol also is a major player in reducing body inflammation during times of stress (Doc Snipes, 2020; Dr. Eric Berg DC, 2016). In addition to increasing blood sugar and reducing inflammation, cortisol also triggers the release of adrenaline, which helps a person stay highly energetic, strong, and focused (Doc Snipes; 2019; Doc Snipes 2020). Cortisol also takes the body’s “feel-good” hormone, dopamine, and breaks it down into norepinephrine; a unique chemical that increases a person’s overall “focus and motivation” (Snipes, 2017, 12:39-12:42). Cortisol also triggers the production of glutamate, which is another special neurochemical that helps a person “get up and go”, especially in times of stress (Snipes, 2017, 12:55-13:00).
In addition to reviving the body up, cortisol also turns things “down ” in the body, like the immune system, sex hormone production (i.e., testosterone and estrogen), sleep/calming chemicals (i.e., serotonin, melatonin), and other important body systems (i.e., the digestive system) (Snipes, 2017). The reason why cortisol turns all of these other functions down is so that all of the bodies internal resources can be devoted solely to helping a person stay vigilant and alert in the face of stress and danger (Doc Snipes, 2020; Doc Snipes, 2017).
In sum, the overall purpose of a person’s danger brain is to tell them that now is NOT the time for them to relax, eat, or have fun, but is rather the time to stay VERY alert and focused so they can survive whatever challenging situation they find themselves in (Snipes, 2017).
The Five F’s of Stress: Fight, Flight, Freeze, Fawn, & Forget
Once a person’s danger brain has been activated, then their body will tend to respond to stress in any one of the following five ways: 1) fight, 2) flight, 3) freeze, 4) fawn, or 5) forget (what is identified as the 5 “F’s of Stress) (Van Der Kolk, 2014; Snipes 2021).
The first stress response is fight. This response is characterized by a strong desire to want to take on whatever stressor may be present (i.e., literally wanting fight/ become more hostile/aggressive). The flee or “run response” is associated with a person wanting to avoid/escape the precarious situation. The freeze response happens when a person feels unable to move or what is commonly known as a “deer in headlights” type-of look (Snipes, 2021, 4:45-47) The fawn response is a tendency for person to want to bend over backwards/become overly pleasing to what or whomever is perceived as stressful. Finally, the forgetting or “forget it” response is a common stress response for those who are faced with ongoing, continuous stress, and eventually feel utterly hopeless so they just give up (For more information, on the F ’s of Stress, click here) (Snipes, 2021).
Getting “Stuck” In Stress
Although it is easy to see how running from something like a bear while camping in the woods can can turn on a person’s danger brain, it is also important to know that even every day, little human things can trigger it to (Snipes, 2019; Snipes, 2020). For example, being stuck in traffic, worried about paying bills, not eating the right foods, staying up all night with a crying baby, having a fight with your partner, giving a big speech, and even living by a noisy airport can all trigger a person’s danger brain/stress response (Snipes, 2019; Rothenburg & MaGrath, 2016).
The danger brain works like a champ in the face of acute stress; however, if a person feels like the stress or danger never leaves, then their danger brain will constantly pump stress hormones through their body. When this begins to happen, then those once helpful stress chemicals like cortisol, eventually start to become toxic to the body leading to all sorts of mental and physical health problems; something we will explore in Part II of this Autonomic Nervous System & Mental Health article series (Doc Snipes, 2020; Torrezan et al. 2018; Sherin & Nemeroff, 2011).
CLICK HERE TO GO TO PART II
References
Altan, S., Berberoglu, B., Canan, S., & Dane, S. (2016). Effects of neurofeedback therapy in healthy young subjects. Clinical and Investigative Medicine, 39 (6), S27-S30. doi:10.25011/cim.v39i6.27496 Alzheimer’s Society. (2017). Can stress cause dementia? Alzheimer’s Society: United Against Dementia. Retrieved from https://www.alzheimers.org.uk/blog/can-stress-cause-dementia
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: Author.
American Diabetes Association. (2022). Understanding Insulin Resistance. Retrieved from https:// www.diabetes.org/healthy-living/medication-treatments/insulin-resistance\
Balt, K., Toit, P. D., Smith, M., van Rosenburg, C. J., (2020). The effect of infraslow frequency neurofeedback on autonomic nervous system function in adults with anxiety and related diseases. Neuroregulaton, 7 (20), 63-74. doi:10.15540/nr.7.2.64
Broderick, P.C. & Blewitt, P. (2020). The Life Span: Human Development for Helping Professionals (5th ed.). Pearson.
Beaupere, C., Liboz, A., Fève, B., Blondeau, B., & Guillemain, G. (2021). Molecular Mechanisms of Glucocorticoid-Induced Insulin Resistance. International Journal of Molecular Sciences. 22 (2), 623. doi: 10.3390/ijms22020623
Cohen, M. P. (2020). Neurofeedback 101. United States of America
Crockett, J. E., Gill, D., L., Cashwell, T., H., & Myers, J. E. (2017). Integrating non-technological and technological peripheral biofeedback in counseling. Journal of Mental Health Counseling, 3, (2), 163-179. https://doi.org/10.17744/mehc.39.2.06
Doc Snipes (Producer). (2020). Cortisols impact on health and mood: PACER Integrative Behavioral Health [Video]. Youtube. Retrieved from https://youtu.be/-QOLW08a39o
Doc Snipes (Producer). (2020). Intro to the HPA Axis PACER Integrative Behavioral Health [Video]. Youtube.https://youtu.be/IDDaolcr4ac
Doc Snipes (Producer). (2021). The Fs of Stress Response [Video]. Youtube. https://youtu.be/D27t-ZzzllI Dr. Eric Berg, DC (Producer) (2016). Cortisol Resistance & Insulin Resistance Explained by Dr.Berg [Video]. Youtube. https://youtu.be/LhXyJCa_b-k
Koberda, J. L. , Koberda, P., Moses, A., Winslow, J., Bienkiewicz, A., & (2014). Z-Score LORETA Neurofeedback as a Potential Therapy for ADHD. Biofeedback, 42 (2), 74-81. doi: 10.5298/1081-5937-42.2.05
Langroudi, M. S., Bahramizadeh, H.&, Mehri, Y. (2011). Schema therapy and family systems theory: The relationship between early maladaptive schemas and differentiation of self. Social and Behavioral Sciences, 30, 634-638. doi:10.1016/j.sbspro.2011.10.123
Melzer, M. T., Manosso, M. L., Yau, S., Gil-Mohapel, J., & Brocardo, P. S. (2021). In pursuit of healthy aging: Effects of nutrition on brain function. International Journal of Molecular Sciences, 22, 1-25. doi: https://doi.org/10.3390/ijms22095026
Moore, K., Hughes, C. F., Ward, M., Hoey, L., & McNulty, H. (2018). Diet, nutrition, and the aging brian: Current evidence and new directions. Proceedings of the Nutrition Society, 77, 152-163 doi: 10.1017/ S0029665117004177 Journal of Clinical and Diagnostic Research. 12(4), BC01- BC04. doi: z10.7860/JCDR/2018/32236.11376
Morrison, James. (2014). Diagnosis Made Easier: Principles and Techniques for Mental Health Clinicians. Guilford Press.
Pears, M. , Kola-Palmer, S., & De Azeveedo, L. B. (2021). The impact of sitting time and physical activity on mental health during COVID-19 lockdown. Sports Sciences for Health, 10, 1-13. https:// doi.org/10.1007/s11332-021-00791-2
Perrin, A. J., Horowitz, M. A., Roelofs, J., Zunszain, P. A., & Pariante, C. M. (2019). Glucocorticoid resistance: is it a requisite for increased cytokine production in depression? A systematic review and meta-analysis. Systematic Review, 10, 1-24. https://doi.org/10.3389/fpsyt.2019.00423
Rotenburg, S., & McGrath, J. J. (2017). Inter-relation between autonomic and HPA axis activity in children and adolescents. Biological Psychology, 117, 16-25. doi:10.1016/j.biopsycho.2016.01.015. Sarapultsev, A., Sarapultsev, P., Dremencov, E. , Komelkova, M., Tseilikman, O., & Tseilikman, V. (2020). Low glucocorticoids in stress-related disorders: the role of inflammation. Stress, 23 (6), 651-661.https://doi.org/10.1080/10253890.2020.1766020
Sherin, J. E., & Nemeroff, C. B. (2011). Post-traumatic stress disorder: the neurobiological impact of psychological trauma. Dialogues in Clinical Neuroscience, 13, (3), 263-278. doi: 10.31887/ DCNS.2011.13.2/jsherin
Shiuchi, T., Otsuka, A., Chikahisa, S., & Séi, H. (2021). Feeding Rhythm-Induced Hypothalamic Agouti Related Protein Elevation via Glucocorticoids Leads to Insulin Resistance in Skeletal Muscle. Internal Journal of Molecular Sciences, 22, 1-18. https://doi.org/10.3390/ijms221910831
Snipes, E.D. (2019). Lifestyle Factors Contributing to HPA-Axis Activation and Chronic Illness in Americans. Archives in Neurology & Neuroscience, 5, 2. doi:10.33552/ANN.2019.05.000608 Tengeler, C. A., Kozicz, T., & Kiliaan, A. J. (2018). Relationship between diet, the gut microbiota, and brain function. Nutrition Reviews. 76 (8), 603-617. doi: 10.1093/nutrit/nuy016
Torrezan R, Malta A, de Souza Rodrigues W.D.N., Dos Santos A.A.A., Miranda R.A., Moura EG, Lisboa P.C., & de Freitas Mathias PC (2019). Monosodium 1-glutamate-obesity onset is associated with disruption of central control of the hypothalamic-pituitary- adrenal axis and autonomic nervous system. Neuroendocrinology, 31 (6), e12717. doi: 10.1111/jne.12717
Van der Kolk, B. A. (2014). The body keeps the score: Brain, mind, and body in the healing of trauma. New York: Viking
Walsh R (2011). Lifestyle and mental health. American Psychologist 66, (7): 579 – 92.World Science Festival. (Producer). (2019). The Nuts and Bolts of Better Brains: Harnessing the Power of Neuroplasticity [Video]. Youtube. https://www.youtube.com/watch?v=59ODYOaUbX4&t=987s Yalom, I. D., & Leszcz, M. (2020). The theory and practice of group psychotherapy (6th ed.). Basic Books
