Polyvagal Approaches: scientifically questionable but useful in practice

Journal of Psychiatry Reform vol. 10 #11, October 2023

Caroline Giroux, MD FRCPC¹, Daniel Ahlers, MD², Alyssa Miawotoe, BS³

Author information:

1. Caroline Giroux, MD, FRCPC, Professor of Psychiatry, Psychiatrist, University of California, Davis Medical Center, Department of Psychiatry and Behavioral Sciences, Sacramento, California, USA. [email protected]
2. Daniel Ahlers, MD, Psychiatrist, Sacramento, CA
3. Alyssa Miawotoe, BS, fourth-year medical student, University of California Davis School of Medicine, Sacramento, CA

Introduction

The Vagus Nerve and Autonomic Insight

Trauma is not an event, but an experience consisting of various layers of response to a stressful event. Trauma is a transdiagnostic phenomenon exemplary of the intersection between body, affect and behavior. Psychological trauma not only impacts cognition, emotion, and belief, but affects the physical body, especially at the level of the autonomic nervous system, creating a ripple effect on many systems and organs and affecting the whole person. This essay elucidates a framework that aims to help people unblock the healing potential intrinsically available within their own bodies.

Stephen Porges’ polyvagal theory provides explanatory power, shedding light on the symptoms of trauma as autonomic nervous system dysregulation and modeling how we can effectively intervene. According to Porges’ theory [1], which is derived from his study on comparative neuroanatomy, the vagus nerve is viewed as the primary conduit of connection between the brain and the body. He describes three evolutionary circuits arranged in a hierarchical manner that engage unconsciously based on the perception of danger in the environment. The states produced by these three circuits are named the immobilization, mobilization, and social engagement circuits.

The immobilization circuit, mediated by the dorsal vagal nerve, is comprised of unmyelinated fibers that project to the subdiaphragmatic viscera. This system is shared with our reptilian ancestors, and represents the “freeze” response to life-threatening situations in which no escape is possible. Chronic activation of this circuit is associated with dissociative states, depression, feeling “numb,” and gut issues (e.g. irritable bowel syndrome).

The mobilization circuit is more commonly known as the “fight/flight” response. A reduction of vagal tone supports sympathetic activation, allowing for decisive action in response to environmental threats.

Trauma results in chronic activation of these two “danger mode” circuits due to a persisting sense of threat, either as a response to ongoing stress or an unprocessed emotionally overwhelming experience.

Porges proposes a uniquely mammalian social engagement circuit, mediated by the ventral vagal nerve, sits at the top of the hierarchy; when engaged, the others are partially inhibited. Its myelinated fibers project to the heart, bronchioles, and striated musculature of the face and neck. This “bidirectional coupling between spontaneous social engagement behaviors and bodily states” allows facial expressions, vocalizations, and gestures to serve as a portal to regulating autonomic activity.

Ideally, most of our time should be spent in this “safety mode,” with the other circuits engaging in a hybrid manner. The combination of the ventral vagal and sympathetic system is typified by play, while combining ventral vagal and dorsal vagal system is seen in situations of intimacy and rest. These hybrid states allow for co-regulation and fine-tuning of danger mode responses without fear.

Porges coined the term “neuroception” to describe the body’s capacity for environmental risk assessment independent of conscious awareness. Psychoeducation on how our body automatically reacts to keep us safe can help patients gain awareness of their body and rewrite trauma narratives. Nonverbal communication, including vocal prosody and facial expression, can be both a window into our patients’ bodily states and an effective tool for creating safety.

Distressed individuals seeking therapy spend much of their time living “in their minds.” Psychotherapy is mediated by spoken language, leading many to reductively refer to the process as “talk therapy” and inadvertently neglecting the vital importance of nonverbal aspects of the therapeutic encounter. Potential limitations of conventional psychotherapies include:

• Overemphasis on cognitive aspects, with reinforcement of helplessness narratives or schemas
• Risks neglecting the impact on the body
• Can be unduly prolonged and cost-ineffective
• Critical incident debriefing in the aftermath of trauma is an extreme form and can be counter-productive (therefore, contra-indicated) [2]

Therefore, it is not surprising that progress in psychotherapy can be slow, if there is any. Thankfully, many modern psychotherapies have embraced the role of the body and nonverbal communication in the psychotherapeutic process. Relational psychoanalyst Steven Knoblauch encourages expanding clinical attention to body rhythms, comparing the clinical encounter to improvisational jazz [3]. David Wallin eloquently demonstrates the importance of working with the body in therapy within the context of attachment theory [4].

Clinicians are also regularly confronted with the limitations of DSM, a descriptive guide that names disorders on a surface level and focuses on the periphery of phenomena that have deeper roots. These various disorders label permutations of human suffering, but they do not point in the direction of ways to heal. Therefore, we find that autonomic hyperreactivity represents a more useful complementary framework to understand trauma manifestations.

Critiques and Alternative Explanations

The polyvagal theory has generated significant debate within the scientific community with most critiques centered around biological claims and availability of evidence, the most contested domains being neural pathways and mechanisms. As medical trainees (AM), we learn about the classic roles of the four vagal nuclei housing sensory (viscera, taste, touch), motor (oropharynx, larynx), and parasympathetic fibers (thorax, abdomen). Critics argue that the roles of the different vagal nuclei are not accurately portrayed by the theory and that there is no evidence thus far supporting these roles (e.g. dorsal vagal nucleus involvement in passive defense response) [5]. Paul Grossman critiques the biological foundations of the polyvagal theory in his 2023 article “Fundamental challenges and likely refutations of the five basic premises of polyvagal theory” [6].

Grossman claims the first principle is flawed as it argues that neurogenic bradycardia and respiratory sinus arrhythmia (RSA) are controlled by different branches of the vagus nerve. He points to existing evidence that demonstrates the primary vagal mediator of mammalian heart rate and cardiac parasympathetic outflow is the ventral nucleus ambiguus with little to no input from other vagal branches.

The second principle states that neurogenic bradycardia is a relic of reptilian ancestors and is mediated by the dorsal vagal motor nucleus (DVMN). Grossman argues that the DVMN has not been shown to have influence on bradycardia or heart rate, and that emotional freezing response is predominantly related to ventral nucleus ambiguus activity.

Grossman refutes the third principle which suggests that regulating vagal tone via the nucleus ambiguus is a mammalian sociobiological adaptation to help cope with environmental changes in order to maintain social communication and metabolic homeostasis. He indicates that this phenomenon is not exclusive to mammals and is shown in studies of non-mammalian species.

The fourth principle claims that the amplitude of RSA can be used as a measure for vagal tone. Grossman maintains that current scientific evidence demonstrates target-organ specificity of vagal control, and although RSA amplitude may show respiratory modulation of cardiac vagal control, it does not reflect broader overall vagal tone.

Finally, the fifth principle claims that emotional expression will produce changes in RSA and bronchomotor tone mediated by the nucleus accumbens. Grossman states that differences in resting cardiac vagal control have not been correlated with vagal bronchomotor tone, and that emotional expression is determined by a wide range of structures and mechanisms besides the vagus nerve.

Along with Grossman, other critics argue that the polyvagal approach is too vague and broad to empirically test, and that pre-existing models may better explain the phenomena. Some well-studied alternative explanations include the classic autonomic nervous system model, multiple system perspectives, emotional regulation theories, cognitive appraisal model, affective neuroscience, and developmental psychology. For instance, the fight, flight, and freeze response are based on the classic autonomic nervous system model of fear circuits, and the primary brain center for social engagement, emotion, and attachment is the limbic system.

In summary, the phenomena described in the polyvagal theory may not be solely derived from vagal pathways. While it is necessary to acknowledge critiques of the polyvagal theory, it is also possible to recognize the value in its conceptual framework for understanding complex phenomena in trauma and the various advantages to using aspects of this approach in clinical practice (Table 1).

Table 1- Advantages and disadvantages of polyvagal approaches

Applications/clinical relevance:

I (CG) have often witnessed a discrepancy in patients’ awareness: there can be a level of insight that seems promising, such as the ability to name their struggles, symptoms, and patterns, probably because they have observed them and identified them or because others pointed these out to them. However, these patients often have difficulty understanding this at an emotional level. It is as if the emotional and cognitive components are out of sync. This is not surprising because trauma creates a split, a major mind-body disconnect, clinically manifested in the form of dissociation, unconscious splitting, etc. There is dissociation when the dorsal branch of the vagus nerve is overly solicited. Anatomically, it is interesting to see that its location is almost symbolic; the dorsal vagal connects the brain/mind and the abdomen, home to our “gut”, which is often equated with intuition. It is a beautiful bridge we should teach our patients to cross, linking the experiential with the conceptual.

When to recommend?

• In our clinical work as we seek to help re-establish a sense of safety and connection in survivors of trauma (whether it is natural disaster, developmental trauma, or toxic environments)
• Lifestyle hygiene to maintain self-regulation skills, enhance creativity, etc.
• When the patient prefers non-pharmacological treatments, or is curious about this approach

Some examples of practical exercises that anyone can benefit from include:

• Humming, singing
• Dancing
• Deep breathing
• Yoga (e.g. pranayama yoga)
• Meditation
• Equine and other pet therapy
• Artistic self-expression
• Being surrounded by people who are supportive, affirming, attuned (which leads to co-regulation. If stress can be somewhat contagious, so is relaxation or safety!)

Conclusion

Trauma affects the whole body. Survivors often try to use their minds to make sense of it without much success. Thus, the major focus of healing trauma should happen within a framework that emphasizes integration of bodily experiences. Despite valid neurobiological critiques of the model, we find the polyvagal theory to be a useful paradigm for trauma recovery and psychosomatic healing. It synergizes with and operationalizes attachment theory because secure attachment is dependent on connection and co-regulation with safe others in the environmental surround. Psychotherapies informed by mind-body integration modalities (such as deep breathing, humming, yoga, art, etc.) can facilitate self-regulation and a sense of safety in the world. There are countless variations of such activities that can enhance resilience. Vagal exercises are within everyone’s reach and can easily be taught to our patients, in the office or in group therapy settings. Polyvagal approaches seem cost-effective and there is a plethora of available resources.

By increasing inner awareness and encouraging situations of safety, attunement, and connection, we help our patients rebalance their autonomic nervous system. Such a relationship engenders freedom from the fortress they built in response to trauma and shifts their nervous system’s focus from defensive protection to life-sustaining connection.

References:

1. Porges, W. “The polyvagal theory: New insights into adaptive reactions of the autonomic nervous system.” Cleveland Clinic Journal of Medicine, 2009; 76(Suppl 2): S86–S90. https://doi.org/10.3949/ccjm.76.s2.17
2. Knoblauch, S.H. “Body rhythms and the unconscious: Toward an expanding of clinical attention.” Psychoanalytic Dialogues, 2005; 15(6), 807–827. https://doi.org/10.2513/s10481885pd1506_2
3. Rose, S.C., Bisson, J., Churchill, R., & Wessely, S. “Psychological debriefing for preventing post traumatic stress disorder (PTSD).” The Cochrane Database of Systematic Reviews. 2002, CD000560. https://doi.org/10.1002/14651858.CD000560
4. Wallin, D.J. Attachment in Psychotherapy. Guilford Press, 2007.
5. Neuhuber, W.L. and Berthoud, H.R. “Functional anatomy of the vagus system: How does the polyvagal theory comply?” Biological Psychology, 2022; Volume 174. https://doi.org/10.1016/j.biopsycho.2022.108425.
6. Grossman, P.M. “Fundamental challenges and likely refutations of the five basic premises of the polyvagal theory.” Biological Psychology, 2023. Volume 180. https://doi.org/10.1016/j.biopsycho.2023.108589