Polyvagal Theory Was “Debunked” - Here’s What You Need To Know
In case you haven’t heard, the scientific foundation that Polyvagal Theory is based on was torn apart in an article titled, “Why The Polyvagal Theory is Untenable.”
(You can read the full article here.)
It was published a few weeks ago in the Clinical Neuropsychiatry journal and critiqued five main tenets of Polyvagal Theory.
This has rocked the wellness world…primarily because Polyvagal-informed language has become embedded in somatic and nervous system regulation work.
The good news?
Somatic work and nervous system regulation work ≠ Polyvagal Theory
However, there is a lot of overlap and I would be remiss not to acknowledge the ways in which Polyvagal Theory has contributed to this industry.
Concepts like:
shifting in and out of states
adaptive responses (geared towards protecting and ensuring survival)
neuroception (how the brain is perceiving the environment)
the social engagement system (cranial nerves that innervate the face and aid in communication and connection)
have all been fundamental to the development of somatic and nervous system work.
I use these concepts - and others - on a regular basis (and will continue to use them - for reasons I’ll go into next week).
However, the article by Grossman, et al. cannot be ignored.
Here’s what’s important for you to know…
What is Polyvagal Theory (PVT)?
Developed by Stephen Porges, PVT proposes that the autonomic nervous system evolved in a hierarchical way, with three distinct response circuits (with the possibility of hybrid states) governing human behavior and emotion:
A ventral vagal system supporting social engagement and calm
A sympathetic system driving fight-or-flight
A dorsal vagal system triggering freeze/shutdown in life-threatening situations
Grossman, et al. provided the following critiques of Polyvagal Theory:
1. On Respiratory Sinus Arrhythmia (RSA) as a measure of vagal activity
RSA has been used in clinical settings to measure vagal tone and the effects of treatments for PTSD, anxiety, and heart-related issues.
Grossman, et al.’s position is that RSA is not an accurate or reliable measure for autonomic function because RSA can be affected by a number of factors, including breathing rate and depth, blood pressure, sympathetic nervous activity, age, and local cardiac mechanisms.
This means that using RSA to measure autonomic function and vagal tone is no longer fully supported by evidence and needs to be investigated further. While this doesn’t affect clinical practice for most therapists or coaches using a Polyvagal-informed approach, RSA is no longer recognized as an effective measure of the effects of Polyvagal-informed treatments or practices.
2. On the dorsal vs. ventral vagal distinction
Evidence shows that it is the ventral branch of the vagus nerve (Nucleus Ambiguus) that plays a role in defense mechanisms and protective strategies instead of the dorsal branch (a.k.a. dorsal motor nucleus of the vagus).
Therefore, the shutdown/collapse/immobilization state is not associated with the dorsal branch of the vagus nerve, as was previously thought. The state that we knew as “dorsal vagal shutdown” has no physiological basis and, therefore, does not exist. This also means that the autonomic hierarchy that is standard in Polyvagal-informed psychoeducation (Dorsal Vagal Shutdown -> Sympathetic Activation -> Ventral Vagal Safety) is not accurate either.
Shutdown/collapse/immobilization is still recognized as an observable state with certain associated psychological signs and symptoms, but our physiological understanding of it is changing. This will have implications on the language we use in clinical practice, and how we conceptualize and communicate the experience of shutdown.
3. On the evolution of the vagus nerve
Porges claimed that what differentiates mammals’ autonomic nervous system from reptiles is that mammals developed myelinated fibers in their vagus nerve (specifically the ventral branch/Nucleus Ambiguus) and that reptiles do not have myelinated fibers.
(Myelinated fibers are nerve fibers that have a little extra fat sheathing them, which can speed up communication from one end to the other.)
However, myelinated fibers DO also exist in the dorsal branch AND in reptiles (not just in the NA/ventral branch in mammals)
While this doesn’t have much bearing on clinical practice, it is important to note that a key tenet of the theory does not hold up to current scientific evidence.
4. On social behavior in non-mammals
Porges’ assertion that reptiles do not have the capacity for prosocial behavioral or autonomic flexibility is untrue. Porges claims that it is the myelinated fibers (see above) in mammals’ ventral branch (NA) that enable them to have complex prosocial interactions and behaviors that are unique to mammals.
Porges also claims that reptiles have unmyelinated preganglionic fibers in the dorsal branch (as opposed to the myelinated fibers mammals have in the ventral branch), but Grossman, et al. state that this is objectively untrue, as there is scientific evidence that reptiles do have myelinated fibers in their dorsal vagal branch.
Grossman, et al. also share that reptiles have rich social lives, which may contradict some of Porges’ assertions, such as the one that reptiles have low behavioral flexibility and rely primarily on defensive behaviors, whereas mammals have high behavioral and autonomic flexibility.
5. On citations and references
Grossman, et al. also took issue with Porges’ references. They claimed that 37/47 references were written/authored by Porges himself and that this doesn’t exactly instill confidence that there is solid scientific backing of Polyvagal Theory (outside of what he has published himself, at least).
They also claim that, “Half of the physiological articles are inaccurately cited, both with respect to authorship and journal source.” I’m not sure how this passed peer review (I’ll admit that I didn’t check all of the references myself), but it does cause me to doubt the validity of the foundation that Polyvagal Theory has been built upon .
Discussion & Clinical Implications
My take on this debate is that much of it is semantics and about identifying the “truth” about niche details that don’t actually affect clinical practice at all (except for the use of RSA as a measure in very specific situations).
When I was first reading the article by Grossman, et al., I remember feeling outraged that those 39 scientists (not therapists, not coaches, not healing practitioners, not bodyworkers) were tearing apart a framework that has not just changed my life, but the lives of many people that I’ve worked with, educated, and trained with.
The analytical, academic part of my brain says: yes, Grossman, et al. make some good points. Are they likely colored by subjective interpretations of past research and data (just as Porges’ work is)? Most likely. However, even after reading Porges’ recent article (and having learned, read, trained in Polyvagal-informed practices for years), I am inclined to side with Grossman, et al. on their critique.
And while I am curious about why Porges did not address that the dorsal vagal branch does NOT, in fact, mediate the shutdown/immobilization/collapse response (which was revealed in published articles from 2016 and 2022) in his most recent article at the end of last year, I don’t think either side of the debate is 100% correct.
Yesterday evening, as I was revising this post before publishing, I came across this post by Ellen Heed, an expert in using bodywork to heal scar tissue. She made the point that nervous system regulation and somatic healing are not just physiological. They are also “chemical, mechanical, fluidic, fascial, endocrine, immune, and neural” (and energetic). She shared some important insights into the vagus nerve itself, such as the fact that there is no clear distinction between the vagus nerve and the sympathetic nervous system, let alone between the ventral and dorsal branches of the vagus nerve.
It is all interconnected. And autonomic states? Well, they can’t be reduced to a single nerve because they are whole system responses.
As a result of this, our understanding of different states (including the physiology, sequencing, and functioning) will shift and our language will change to reflect that (i.e., “Dorsal vagal shutdown” → just “shutdown” or “collapse”).
As for the integrative framework that Grossman, et al. suggest…
I like Ellen’s Regulation Rainbow and her way of understanding the states we shift in and out of.
But this isn’t about having the perfect framework or model.
That doesn’t exist and it never will as long as the body holds mysteries that science cannot explain.
It’s about having a framework that allows for multiple perspectives to be integrated into a framework or system that works to create change in the people you work with. This is why I think that a Polyvagal Model (not theory - model), in combination with other modalities and approaches (i.e., neurobiological, cognitive, behavioral, energetic, somatic, etc.), still holds value in modern clinical practice.
In my work, I pull on ALL of my experience (integrative nutrition coaching, systems thinking, somatic work, cognitive behavioral therapy, creative therapy modalities, conscious movement, hypnosis, and Polyvagal-informed practices) to understand what my clients are experiencing and how to guide them to their natural state of aliveness so that they can create lives full of joy, pleasure, play, and ease.
I’m passionate about learning, which means that my framework is constantly evolving, but it is based in these 3 concepts:
Regulating the body/nervous system and returning it to a state of safety and engagement with life.
Repatterning the stress response.
Integrating the changes made.
If you want to learn more about the framework I’ve developed to help people create change in their lives (without being in therapy for years), consider checking out some of my upcoming workshops and events or send me an email: miarbecker@gmail.com.