It’s Not in Your Head: The Nervous System’s Role in Mental Health
Anxiety and depression aren’t “just in your head”—they’re closely tied to how the nervous system responds to stress. Research links these conditions to autonomic nervous system imbalance, where the body remains stuck in a state of fight-or-flight. Chiropractic care may help support nervous system regulation by addressing spinal dysfunction and improving the body’s ability to adapt to stress.
The Autonomic Nervous System
“Autonomic” refers to the automatic or involuntary part of your nervous system. It controls all of the daily functions that you don’t have to think about — your breathing, heart rate, blood pressure, digestion, etc.
The autonomic nervous system is divided into two different sides…
Sympathetic: This is also known as the fight-or-flight side of the nervous system. It activates in response to perceived stress or danger (either physical or mental/emotional), triggering physiological responses like increased heart rate and blood pressure, shallowed breathing, and increased muscle tension. These are crucial functions in the context of survival, when there is a need to either protect yourself or escape.
Parasympathetic: This is also known as the rest-and-digest side of the nervous system. In the absence of stress, it serves to maintain normal daily functions like digestion, immune health, reproduction, etc. It also helps your body rest and recover.
While both sides are always active, the body is designed to shift into primarily one state or the other according to the demands of your environment. A balanced nervous system can make this transition smoothly and appropriately.
Dysautonomia refers to an imbalance in sympathetic and parasympathetic activity, typically favoring the sympathetics. Fight-or-flight activity is designed for short bursts, but in the presence of chronic stress, it can be prolonged. Eventually, the nervous system becomes stuck in this state, contributing to issues like fatigue, anxiety, depression, and insomnia.
Why the Spine Matters
Spinal anatomy is closely related to the autonomic nervous system. Nerve fibers associated with each side (sympathetic and parasympathetic) can be found in specific regions of the spine…
Sympathetic: C6-L5 (lower neck into low back — the middle of the spine)
Parasympathetic: C0-C5 and L5-sacrum (base of skull, upper neck, and low back into the hips — top and bottom of the spine)
* Note: Different sources will vary slightly in exactly where they draw the line between sympathetic/parasympathetic regions, but the general locations remain consistent. Our estimates are based on Dr. Gonstead’s findings.
So why does this matter? — Because nerve dysfunction in a specific region of the spine can lead to either too much or too little activity in one side of the autonomic nervous system, creating an imbalance.
The Subluxation
A subluxation is when there is misalignment and restricted motion between two or more vertebrae in the spine, which puts pressure on nerves, and interferes with communication between the brain and body.
This not only causes local dysfunction related to the affected nerve, but it can also cause systemic (whole-body) dysfunction by influencing the autonomic nervous system (Kent, C., 2018).
Local dysfunction: localized inflammation and pain, dysfunction in specific muscle groups and organ systems
Systemic dysfunction: perception of pain (increased sensitivity), whole-body inflammation, autoimmune activity, dysautonomia
Chiropractors specialize in identifying and correcting subluxations. So while we don’t claim to treat conditions like chronic inflammatory diseases, autoimmune diseases, and mental illnesses, there is evidence to suggest that the treatment of subluxations can influence these conditions by addressing underlying dysfunction.
History of Chiropractic and Mental Illness
This relationship began in the 1920s, with the establishment of several inpatient mental health facilities which implemented chiropractic care as the primary clinical intervention. Patients were given “sunny and bright” rooms, and balanced meals including fresh garden vegetables. They were also checked regularly for nerve interference, and chiropractic adjustments were administered accordingly (Kent, C., 2018).
It was found that these facilities had a significantly higher “cure and discharge rate” than traditional mental hospitals.
The rate at North Dakota State Hospital ranged from 18-27%, compared to 65% at the chiropractic facility known as Forest Park (Kent, C., 2018).
Unfortunately, these facilities were eventually closed due to licensing and third party pay issues. Insurance companies would not cover their care, and only full-service hospitals were eligible for licensure (Kent, C., 2018).
Modern Evidence
Autonomic imbalance — specifically favoring increased sympathetic activity — has been regularly observed in patients with anxiety and depression (Kiani et al., 2020). This is commonly assessed using heart rate variability (natural variations in the time between consecutive heartbeats). Decreased HRV is associated with autonomic imbalance, and this is precisely what we find in patients with anxiety and depression (Kent, C., 2018).
Interestingly, HRV has been found to respond favorably to chiropractic correction of vertebral subluxations (Kent, C., 2018).
The vagus nerve also plays an important role in mental health and the autonomic nervous system. It is often called the “wandering nerve” because of it’s many connections and functions. This nerve originates from the brain stem, and passes through the cervical (neck) region on its way to the chest and abdomen (Kiani et al., 2020). Along the way, it provides crucial parasympathetic activity throughout the body — in the heart, lungs, blood vessels, digestive system, and more. The amount of vagus nerve activity is often referred to as vagal tone…
Increased vagal tone = more parasympathetic activity = rest and digest
Decreased vagal tone = less parasympathetic activity = sympathetic dominance (fight-or-flight)
It’s no surprise then that anxiety and depression are associated with decreased vagal tone. Fortunately, there are ways to stimulate the vagus nerve, and the resulting increase in activity has been shown to increase blood flow to regions of the brain involved in major depressive disorder (MDD). It also produces changes in the same brain regions and neurotransmitters as conventional anti-depressants. Vagal stimulation can be a natural alternative to these medications, producing similar results more gradually over time (Kiani et al., 2020).
Lastly, it’s important to note that while often overlooked, pain is also a significant contributor to mental health. Living in pain — especially for long periods of time — can be frustrating and discouraging, and your nervous system experiences this stress on a physiological level. This explains why 50-65% of patients with chronic pain are also diagnosed with depression (Kiani et al., 2020).
Chiropractic Intervention
Based on our understanding of the nervous system and mental health, there are a few ways that chiropractic care can help…
First, it can be as simple as getting the patient out of pain. Spinal subluxations often produce inflammation and pain, which can be relieved through gentle and specific chiropractic care.
Second, chiropractic care can improve the body’s response to stress by affecting the autonomic nervous system.
Increased heart rate variability = more adaptability, and appropriate transitions between sympathetic and parasympathetic
Vagal stimulation = increased parasympathetic activity = a calmer nervous system that can rest and recover
A case study from Ochsner and DelVicario helps bring these concepts to life by explaining the chiropractic management of a 30 year old female with anxiety and depression…
The patient was diagnosed 8 years prior, and was previously treated with Lexapro and Clonazepam. Not satisfied with the results, she sought alternative care from a chiropractor. A detailed exam was performed, including x-rays and a thermal (Insight) scan. Based on the findings, the patient was given an individualized care plan.
Within the first 2 weeks of care, the patient’s panic attacks reduced in frequency from 7x/wk to once per week. By the fourth month of care, she reported that she was no longer experiencing any anxiety or depression. And after 2 years of wellness care, she was off of all medications.
In Conclusion
The relationship between the nervous system and mental health essentially comes down to how well your body is able to respond and adapt to stress. In the words of Hans Seyle,
"Stress is not necessarily bad for you. It is also the spice of life, for any emotion, any activity causes stress...the same stress that makes one person sick is an invigorating experience for another...Complete absence of stress is incompatible with life since only a dead man makes no demand on his body or mind (Ochsner and DelVicario, 2018)."
Seyle describes two types of stress: DIS-tress (or “bad” stress) and EU-stress (or “good” stress). The difference comes down to your nervous system…
“Whether we experience a pleasant or unpleasant result from an event depends upon how our nervous system perceives, processes, and interprets that event (Ochsner and DelVicario, 2018).”
The take-away from all of this is that while chiropractors do not claim to treat mental health conditions, we do treat spinal subluxations. Correcting subluxations can affect mental health by alieviating pain and helping to restore balance in the autonomic nervous system. This encourages your body to experience more eu-stress and less dis-stress.
References
Kent, C. (2018). Chiropractic and Mental Health: History and Review of Putative Neurobiological Mechanisms. Journal of Surgery, Operative Techniques and Anesthesia.
Kiani, A., et al. (2020). Neurobiological Basis of Chiropractic Manipulative Treatment of the Spine in the Care of Major Depression. Acta Biomedica.
Ochsner, A., and DelVicario, J. (2018). Resolution of Anxiety and Depression Along with Decreased Medication Usage in a 30-Year-Old Female Undergoing Chiropractic Care: Case Report & Review of Literature. Vertebral Subluxation Research.