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Your PNS, the Polyvagal Theory & Addiction: How Exercise Activates the Vagus Nerve and Restores Calm During Recovery

As part of our Addiction: Head to Toe series, we take a deep dive into the peripheral nervous system (PNS) and the latest research about how this region of the body is affected by substance use disorders (SUD). By unpacking the Polyvagal theory, we demonstrate how exercise is used as a clinical tool to re-balance the PNS during sobriety. We also highlight the founder of an innovative trauma-sensitive yoga program who suggests that yoga can help those in addiction recovery take control of their mind and body.

The Nervous System & SUDs

Chronic substance use can ravage the nervous system and its segments: the central nervous system (CNS) – includes the brain and spinal cord, and the peripheral nervous system – includes the nerves outside the brain and spinal cord. Depressants, such as alcohol, slow down the CNS, affecting the neurotransmitter gamma-aminobutyric acid (GABA), leading to sleepiness and relaxation. Stimulants like methamphetamines ramp up the CNS by stimulating dopamine release; however, it also blocks GABA, which prevents the reabsorption of dopamine. This action leads to symptoms of hyperactivity and agitation.

The PNS and its subdivisions, the autonomic and somatic nervous systems, are also greatly affected by chronic substance abuse. The somatic nervous system (SNS) allows our muscles and brains to communicate with each other. The autonomic nervous system (ANS) controls the glands and internal organs, such as the heart and lungs (Clarke, J., 2019). Within the ANS also lie the sympathetic and parasympathetic systems. Stephen Porges, Ph.D., professor of psychiatry at the University of North Carolina, is best known for developing the Polyvagal theory, which beautifully ties all these systems together (Porges, S., 2011). This theory helps addiction professionals understand the interaction between the sympathetic and parasympathetic systems when dealing with trauma, pain, and substance use disorders. The theory includes the vagus nerve (that exits the brainstem and travels through almost every body part) and other branches of the ANS with their corresponding responses, including:

  • Parasympathetic system – immobilization and restoration.

  • Sympathetic system – fight or flight response.

  • Ventral vagal system – calms the physiological state and supports social engagement.

Porges highlights that acute withdrawal from substances causes significant disruptions throughout the ANS, leaving most individuals in the “fight or flight” mode. He also calls this “neuroception” – a subconscious process in which our neural circuits are reading/scanning cues of danger in our environment (Porges). This effect results in feelings of agitation, aggression, and stress. Some may feel the effects long after withdrawal – a condition called Post-Acute Withdrawal Syndrome (PAWS). This state can persist for weeks or months. According to UCLA’s Semel Institute for Neuroscience and Human Behavior, PAWS symptoms include:

  • Fatigue or insomnia

  • Increased levels of anxiety

  • Agitation, tremors, and twitchy behavior

  • Mood swings with severe highs and lows

  • Chronic pain

HPA Axis

When a person stops drugs or alcohol, their hypothalamic-pituitary-adrenal (HPA) axis, a primary endocrine pathway, is also thrown off balance. This axis consists of the hypothalamus, the pituitary gland, and the adrenal glands. The hypothalamus releases a corticotropin-releasing hormone that travels to the pituitary gland, triggering adrenocorticotropic hormone release. This hormone travels to the adrenal glands, prompting them to release cortisol. This process forces the body to remain on high alert, even without an imposing threat. Studies find that these alterations in stress responses may also impact relapse risk in chronic substance users (Wemm, S.E. & Sinha, R., 2019).

How Exercise Takes the Body Out of “Fight or Flight” Mode

During addiction recovery, treating SUD withdrawal includes medications like beta-blockers and anti-depressants to relieve anxiety combined with inpatient treatment and counseling. While these treatments are effective and necessary, exercise can also be used as a targeted clinical treatment intervention. During recovery, the entire PNS system needs to be toned down and re-balanced. The amygdala is the region of the brain that sends distress signals to the hypothalamus. Exercise increases serotonin and norepinephrine, which promotes relaxation and calms the amygdala – re-balancing the HPA axis. Physical activity also increases the neurotransmitter GABA and the brain-derived neurotrophic factor (BDNF), which is essential for feeling less agitated and reducing stress (Adlard, P.A. & Cotman, C.W., 2004). According to John J. Ratey MD, associate clinical professor of psychiatry at Harvard Medical School and author of the book Spark: The Revolutionary New Science of Exercise and the Brain, exercise during recovery leads to:

  • Reducing muscle tension – exercise serves as a circuit breaker, similar to beta-blockers, interrupting the negative feedback loop from the body to the brain that heightens anxiety.

  • Teaches a different outcome – anxiety activates the sympathetic nervous system. However, those same symptoms are inherent to aerobic exercise, which is a good thing. If individuals associate the physical symptoms of anxiety with something positive, something the person can control, the fear memory fades in contrast to the healthy one taking shape.

Practicing yoga, Tai Chi, or any other mind-body activity can also help restore the proper balance between the sympathetic and parasympathetic systems. One study found that Qigong had marked beneficial effects on anxiety symptoms among individuals with SUDs. The research suggests that this exercise improved anxiety and depression compared to that of medication (Liu, F. et al., 2020). Yoga also helps alleviate chronic pain for individuals with substance use disorders and provides an alternative coping strategy (Lutz, D.J. et al., 2019). Studies show exercise, like yoga, can re-balance the ANS. However, most people do not understand how this happens in those with SUDs – enter the mind-body connection.

The Vagus Nerve, Yoga, & the Mind-Body Connection

From Steven Porges’ theory, we know the ventral vagal, or social engagement system, is in charge during non-threatening situations. It functions as a kind of brake that slows down our heart and other organs, allowing our system to calm down. Yoga activates the vagus nerve and its branches that regulate the heart, abdominal viscera, face, and breath. The nerve also communicates with the brain. According to Porges, activating the vagus nerve during yoga helps down-regulate the sympathetic nervous system. It allows individuals, especially those with trauma, to attain a sense of self-efficacy while improving their ANS regulation (Porges).

Mike Huggins, the founder of the Transformation Yoga Project (TYP) and author of Yoga for Recovery: A Practical Guide to Healing, understands the vagus nerve’s crucial role, especially in recovery. TYP serves people impacted by trauma, addiction, and incarceration through trauma-sensitive mindfulness-based yoga. Huggins states, “There is a definite link between trauma and substance use disorders. Incorporating trauma-informed methods like yoga into recovery treatment can help people heal from trauma and sustain lifelong recovery.” Huggins explains how using a gentle yoga practice not only activates the vagus nerve, but it teaches those in recovery that they can make choices for themselves. He states, “Yoga activates the parasympathetic region and vagus nerve – decreasing anxiety and reducing stress. During class, we ask for participants to move a certain way or body part. After they move – we ask them – how does this make you feel? In doing so, the person is making the mind-body connection. They are taking control of their body. This gives them calm, confidence, a sense of community, and re-balances their nervous system.”

Follow us as we continue our Addiction: Head to Toe series examining the latest research and insight from healthcare professionals on how exercise may be our best defense in sustaining abstinence and preventing relapse for those in addiction recovery.

Disclaimer: The exercise and medical information in this paper should not be followed without first consulting a medical health professional. This article is for informational purposes only and is not intended to prevent, cure, or treat any diseases.

References:

Adlard, P.A. & Cotman, C.W. (2004). Voluntary exercise protects against stress-induced decreases in brain-derived neurotrophic factor protein expression. Neuroscience. 124(4):985-92.

Clarke, J. (2019, August 5) Polyvagal Theory and How It Relates to Social Cues. Very Well Mind. Retrieved from https://www.verywellmind.com/polyvagal-theory-4588049.

Liu, F., et al. (2020). The effect of tai chi and Qigong exercise on depression and anxiety of individuals with substance use disorders: a systematic review and meta-analysis. BMC Complement Med Ther. 20(1):161.

Lutz, D.J., et al. (2019). Yoga as an adjunct for the treatment of substance abuse. Practice Innovations. 4(1):13–27

Porges, S. (2011). Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-Regulation. New York: Norton.

Semel Institute for Neuroscience and Behavior. Post-Acute Withdrawal Syndrome. Retrieved from https://www.semel.ucla.edu/dual-diagnosis-program/News_and_Resources/PAWS

Wemm, S.E. & Sinha, R. (2019). Drug-induced stress responses and addiction risk and relapse.
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