HPA Axis Dysfunction: The Brain–Body Connection in Chronic Stress and Anxiety
Chronic stress and anxiety are the baseline for many people. The exhaustion, lack of sleep, feelings of anxiousness, and emotional flatness make it difficult to function normally in day-to-day life. But it isn’t just a set of symptoms; it’s your body telling you something is wrong.
What you’re experiencing has a biological explanation. It starts with the hypothalamic-pituitary-adrenal axis, or HPA axis. Understanding how it works, what happens when it doesn’t, and how to fix it can help you feel like yourself again. To help you gain that understanding, this guide will cover:
- Chronic stress and its impact on the HPA axis
- HPA axis dysfunction symptoms
- The brain-body stress connection
- Chronic stress treatment for adults
- How to support HPA axis recovery
Chronic Stress and HPA Axis
The HPA axis is your body’s control system for stress. It has three parts: the hypothalamus, pituitary gland, and adrenal glands. Each component works in sequence to usher your body from a resting state to a vigilant state in response to a real or perceived threat.[1]
This system works well under normal circumstances. Its self-regulatory features mean that your body is ready to act when needed, and once the threat is over, it returns to baseline.[2] However, sometimes the HPA axis can get stuck in the “on” position. That dysfunction can lead to chronic stress and anxiety.
The Stress Response
When your brain recognizes danger, the hypothalamus jumps into action. Once activated, it triggers a series of events known as the fight-or-flight response: your muscles tense, your attention sharpens, and your heart rate climbs, all in preparation to protect yourself. Meanwhile, processes not essential to the threat response (e.g., digestion) slow down to redirect resources where they’re needed most.[1],[3]
This rapid response is fueled by adrenaline, causing the physical sensations you recognize in times of stress, like a pounding heart and tense muscles.
The HPA axis system, which is driven by cortisol, kicks in after this. Think of the HPA axis as the slower response. It takes several minutes to activate, whereas the adrenal response takes only a few seconds.[1],[4] Where the adrenal response evolved to address short, intense threats, the HPA response sustains your body’s ability to mobilize, then brings your body back to calm.
That’s how it’s supposed to work, anyway. Nervous system dysregulation is common and causes these processes to malfunction. For example, when faced with constant stress, the nervous system might remain activated. Being in a state of low-level alert for an extended period causes immense wear on your body and brain.[5],[6]
What Keeps the Stress Response Activated?
Normally, cortisol tells the hypothalamus and pituitary gland that the threat has passed and the body’s stress response can be turned off. But when chronic stress is involved, that feedback loop is disrupted. The result is that the system loses its self-regulatory capabilities.[7]
The loss of system regulation doesn’t happen overnight, though. Instead, it develops over weeks of sustained stress levels, which explains why many people don’t even notice that something is wrong until the symptoms are well established.[8]
In other words, the fatigue, brain fog, social withdrawal, and other symptoms of HPA dysregulation (discussed in detail below) become normalized over time. You might tell yourself you’re just tired or getting older or too busy, when in fact it’s a cortisol imbalance mental health issue that could have substantial effects on your overall health.[9]
Specifically, elevated cortisol levels damage the hippocampus, the part of your brain that’s supposed to regulate the stress response. Once damaged, the hippocampus can’t do its job, which creates a self-reinforcing cycle of hypervigilance to threats, continued elevation of cortisol, and additional damage.[4],[5],[6]
While the mechanisms for activating the stress response are the same for all of us, the effects of that response depend on our unique experiences and genetics. Still, there are common symptoms to be aware of. Recognizing those symptoms can be clarifying for you, and a long-overdue explanation of how you’ve been feeling.
Chronic Stress and HPA Axis
The HPA axis is your body’s control system for stress. It has three parts: the hypothalamus, pituitary gland, and adrenal glands. Each component works in sequence to usher your body from a resting state to a vigilant state in response to a real or perceived threat.[1]
This system works well under normal circumstances. Its self-regulatory features mean that your body is ready to act when needed, and once the threat is over, it returns to baseline.[2] However, sometimes the HPA axis can get stuck in the “on” position. That dysfunction can lead to chronic stress and anxiety.
The Stress Response
When your brain recognizes danger, the hypothalamus jumps into action. Once activated, it triggers a series of events known as the fight-or-flight response: your muscles tense, your attention sharpens, and your heart rate climbs, all in preparation to protect yourself. Meanwhile, processes not essential to the threat response (e.g., digestion) slow down to redirect resources where they’re needed most.[1],[3]
This rapid response is fueled by adrenaline, causing the physical sensations you recognize in times of stress, like a pounding heart and tense muscles.
The HPA axis system, which is driven by cortisol, kicks in after this. Think of the HPA axis as the slower response. It takes several minutes to activate, whereas the adrenal response takes only a few seconds.[1],[4]
Where the adrenal response evolved to address short, intense threats, the HPA response sustains your body’s ability to mobilize, then brings your body back to calm.
That’s how it’s supposed to work, anyway. Nervous system dysregulation is common and causes these processes to malfunction. For example, when faced with constant stress, the nervous system might remain activated. Being in a state of low-level alert for an extended period causes immense wear on your body and brain.[5],[6]
What Keeps the Stress Response Activated?
Normally, cortisol tells the hypothalamus and pituitary gland that the threat has passed and the body’s stress response can be turned off. But when chronic stress is involved, that feedback loop is disrupted. The result is that the system loses its self-regulatory capabilities.[7]
The loss of system regulation doesn’t happen overnight, though. Instead, it develops over weeks of sustained stress levels, which explains why many people don’t even notice that something is wrong until the symptoms are well established.[8]
In other words, the fatigue, brain fog, social withdrawal, and other symptoms of HPA dysregulation (discussed in detail below) become normalized over time. You might tell yourself you’re just tired or getting older or too busy, when in fact it’s a cortisol imbalance mental health issue that could have substantial effects on your overall health.[9]
Specifically, elevated cortisol levels damage the hippocampus, the part of your brain that’s supposed to regulate the stress response. Once damaged, the hippocampus can’t do its job, which creates a self-reinforcing cycle of hypervigilance to threats, continued elevation of cortisol, and additional damage.[4],[5],[9]
While the mechanisms for activating the stress response are the same for all of us, the effects of that response depend on our unique experiences and genetics. Still, there are common symptoms to be aware of. Recognizing those symptoms can be clarifying for you, and a long-overdue explanation of how you’ve been feeling.
HPA Axis Dysfunction Symptoms
When your body’s HPA axis is in a state of dysregulation long enough, it causes ripple effects throughout your body. On the one hand, you might experience changes in sleep, mood, and cognitive functioning. On the other hand, your immune functioning can become depressed, leaving you more prone to illness. Digestion problems (e.g., bloating, diarrhea), cardiovascular difficulties (e.g., abnormal blood pressure, palpitations), and weight gain are common as well.[2],[9]
This is where the endocrine system and mental health connection come in. Cortisol isn’t just a stress hormone, as is commonly thought. Instead, it affects everything from emotional regulation to brain chemistry. How that cortisol imbalance plays out in your body determines, in part, the symptoms you experience.[9],[10]
HPA Axis and Anxiety Disorders
When the HPA axis is overactive, it keeps your brain’s alarm system on alert. That’s why people with anxiety constantly feel anxious, even when there’s nothing genuinely threatening happening.[11]
The hormonal imbalance anxiety symptoms people have, such as persistent worry, panic, racing heart, and hypervigilance, aren’t random. In reality, they’re the logical result of a stress system that cannot turn itself off. But it isn’t purely a case of not being able to find the snooze button for the alarm; early-life stress plays a role, too.
For example, if you had a difficult childhood growing up in a home where verbal and mental abuse were the norm, your HPA axis might be calibrated to be hypersensitive. Because you were under constant threat, your stress response fires more easily and more intensely, even decades later as an adult.[12],[13]
Given that, anxiety disorders aren’t a case of being too sensitive or overthinking. The dysregulated cortisol and altered brain circuitry that result from HPA axis dysfunction are primary factors in the development of common anxiety-related disorders, like generalized anxiety disorder, PTSD, and panic disorder.[11]
HPA Axis and Depression
The relationship between the HPA axis and depression shows an opposite pattern from anxiety. Instead of being overactive, the HPA system is underactive due to a lower cortisol output. The result is common depressive symptoms like a flat affect, emotional numbness, brain fog, memory problems, and a lack of motivation.[9],[12]
These symptoms often come on the heels of anxiety. It makes sense, too: chronic stress pushes cortisol levels up, resulting in anxiety-related symptoms, but after sustained activation, the system becomes so worn down that cortisol output dips below normal, producing the depressive symptoms listed above. It’s two different stages of the same ongoing process.[5],[9]
Think of it like a feedback loop. Stress dysregulates the HPA axis, which leads to a cortisol imbalance. The result of that imbalance is often symptoms of anxiety and depression. But once those hormones are dysregulated, that imbalance begins to drive mental health symptoms, often independently of whether the original stressor is still present.[7],[9]
Here’s an example. Disrupted cortisol interferes with your sleep quality. Poor sleep further dysregulates cortisol in your body. This, in turn, worsens your depression, which disrupts your sleep even more. Though the original stressor might be gone, the cycle keeps going, preventing your stress response system from turning off.
Understanding whether your HPA axis is overactive or underactive is essential for effective treatment, as the interventions differ depending on which pattern applies to you.
What Is Adrenal Fatigue?
Adrenal fatigue and mental health get a lot of attention in wellness spaces. The symptoms associated with this are very real: chronic exhaustion, emotional depletion, mood instability, and brain fog. However, adrenal fatigue is not a recognized clinical diagnosis.[7]
A more accurate description of adrenal fatigue is HPA axis dysregulation. This is an important reframe because there are many evidence-based interventions to treat it. Adrenal fatigue, on the other hand, suggests that your body’s adrenal glands are wearing out.[7]
Supplements and non-clinical interventions are widely promoted online for this, but these approaches often lack the backing of scientific research.
The Brain-Body Stress Connection
As described above, your brain doesn’t just initiate the stress response; it’s also shaped by it over time. This, in turn, affects how your body responds to stress now and in the future.[5]
And since the same brain regions that interpret threats are also responsible for regulating your body’s physiological reactions to stress, the brain-body stress connection isn’t just a metaphor; it’s an integrated, biological system.
The integration of the mind and body on this front explains why psychological experiences (e.g., financial worries or a relationship breakup) can lead to physical symptoms. Think back to a time when a relationship ended. You might’ve experienced an increased heart rate, sweating, and feelings of dread as you realized the relationship was over.
Understanding this connection isn’t just an interesting academic exercise. It helps explain why stress can make you physically unwell. It also tells us that chronic stress treatment for adults works best when it addresses both the psychological and physiological dimensions of the stress response.
How to Regulate Cortisol Levels and Support HPA Axis Recovery
Stress isn’t something you can eliminate completely from your life. However, you can restore your HPA axis’s ability to respond to stress appropriately and recover from it in a timely fashion.[7]
The mental health and hormone imbalance connection means that strategies to fix the HPA axis’s performance must address your mental health symptoms and the hormonal dysregulation. You can do that by integrating any of the following into your daily routine:[7]
- Prioritize sleep. Focus on sleep hygiene and on creating an environment conducive to quality rest: cool air, little light penetration, no screentime, and a consistent sleep-wake pattern will help regulate the HPA axis.
- Eat well. Too much sugar, caffeine, and processed foods activate the HPA axis. Minimizing your intake of these foods helps regulate cortisol and return the HPA axis to a normal state.
- Exercise. Moderate aerobic exercise is an excellent way to regulate cortisol levels. It also helps improve mood, cognitive functioning, and sleep.
- Practice mindfulness. Mindfulness exercises (e.g., focused breathing, meditation, and yoga) produce measurable changes in the HPA axis and reduce cortisol reactivity.
Making these changes to your daily life is an excellent first step. But if your HPA system is severely dysregulated, professional help might be warranted.
Treatment for Stress-Related Disorders
Stress hormone imbalance treatment is best done as an integrative process, one that looks at lifestyle patterns, stress history, and mental health. The process might unfold like this:
- An intake assessment is conducted, during which you discuss your history, diet, daily habits, and current life stressors with a mental health professional.[7],[13]
- Cortisol testing is done to determine whether your HPA axis is overactive or underactive, as this information guides treatment.[7]
- Screening for other hormonal imbalances, such as blood sugar regulation, thyroid, or reproductive hormones, offers additional details. These screenings are critical since these conditions frequently co-occur with HPA dysfunction.[7]
Fortunately, the landscape of mind-body treatment is expanding and may take many forms. For example, treatment for stress-related disorders often involves psychotherapy. Approaches such as cognitive-behavioral therapy are especially beneficial because they address the emotional and cognitive components of the stress response.[7][11]
Trauma-informed therapy is also an excellent option, particularly if you had early-life adversity. Rather than managing the symptoms of HPA dysregulation, these therapies (e.g., eye movement desensitization and reprocessing therapy) directly address the underlying physiological programming responsible for the dysregulation in the first place.[14]
Changing daily habits is likely to be part of a treatment plan, too. Focusing on the factors discussed earlier, such as improving sleep and nutrition, follows the integrative approach that addresses the whole person: your experiences, symptoms, and recovery.
Mission Connection: Providing Professional Support for Chronic Stress and Anxiety
Learning about HPA axis dysfunction and recognizing that it could be responsible for what and how you’re feeling is a good first step. Reaching out for help is the next step. Mission Connection is a compassionate partner as you set out on a path toward recovery. We’re here to help you find your way back to balance so you can break free from the cycle of chronic stress and begin living your full life again.
