1.7.0

Debunking the Polyvagal Theory

According to Wikipedia (February 2024) on Polyvagal Theory, the PVT is “a collection of proposed evolutionary, neuroscientific, and psychological constructs pertaining to the role of the vagus nerve in emotion regulation, social connection and fear response. The Theory was introduced in 1994 by Stephen Porges in 1994. There is consensus among experts that the assumptions of the polyvagal theory are untenable. PVT is popular among some clinical practitioners and patients, but it is not endorsed by current social neuroscience.“ The text was initially even more antagonistic, but — it seems — some voices brought a more moderate tone.

In this chapter we will go through the group of opponents of PVT.

  • Paul Grossman

  • Edwin Taylor et al.

  • Karemaker

  • Neuhuber and Berthoud

  • Doody, Dinets and Burghardt

  • Around the Autism

  • Internet and Medium

1.7.1

Paul Grossman

Though the writings of Edwin Taylor and Paul Grossman are somehow often intertwined, let us separate them for a while and start with the greatest polyvagal opponent: Paul Grossman. In 2007, Paul Grossman and Edwin W. Taylor wrote Toward understanding respiratory sinus arrhythmia: Relationships to Cardiac Vagal Tone, Development, and Biobehavioral Functions. In the abstract, under point 6, they write«The polyvagal theory contains evolution-based speculations that relate RSA, vagal tone, and behavioral phenomena. We present evidence that the polyvagal theory does not accurately depict the evolution of vagal control of heart rate variability and that it ignores the phenomenon of cardiac aliasing and disregards the evolution of a functional role for vagal control of the heart from cardiorespiratory synchrony in fish to RSA in mammals.» (Grossman, 2007)

With Bernston and Cacioppo (Berntson, 2007), Grossman had already written another article Whither vagal tone, questioning the validity of the Polyvagal Theory. Grossman and Porges have known each other for a long time, as Berntson, Grossman, Porges, and eight other authors had previously published Heart rate variability: origins, methods, and interpretive caveats (Berntson, 1997). 

Dr. Grossman, a psychologist, is Research Director Emeritus of the Department of Psychosomatic and Internal Medicine at the University Hospital of Basel, Switzerland. He has been the principal investigator of several scientific studies examining the effectiveness of MBSR in fibromyalgia, multiple sclerosis, and cancer. He has also taught mindfulness and Buddhist psychology seminars at the University of Fribourg. Likewise, he is also a member and faculty member of the Mind and Life Institute (an international institute for collaboration between Western science and Buddhism).

Grossman has practiced Vipassana meditation for over 30 years and completed an MBSR internship at the “Center for Mindfulness” at the University of Massachusetts Medical School in 1998. With his wife Ulrike Kesper-Grossman, he founded the European Center for Mindfulness in Freiburg in 2011. Keeper-Grossman (1953-2012) was an educator, yoga teacher, and trained psychotherapist before completing her training as an MBSR teacher with Jon Kabat Zinn at the “Center for Mindfulness” in 1994. She worked there for many years and later collaborated closely with him.

ResearchGate

On December 30, 2016, Grossman sent out a “message in a bottle” on ResearchGate: “Does anyone know of any research documenting large heart-rate decreases during episodes of psychological dissociation?” The response was not overwhelming, but Grossman's persistence has allowed him to maintain a small audience of interested readers over the years. Without his courage and perseverance, our project wouldn't exist. The project “Examining Porges Polyvagal Suppositions” is on ResearchGate. Register and search for “polyvagal” to see the project.

I highly recommend this project, which provoked an extensive reaction from Porges (see also the full text): «Grossman has used social media to promote his claim.» However, I’m unsure that «social media» is appropriate for ResearchGate, which is more of a “professional social networking platform.” This academic social networking site has a specialized focus, far away from social media platforms like Facebook, Instagram, or TikTok. 

In 2023, P. Grossman published Fundamental challenges and likely refutations of the five basic premises of the polyvagal theory (Grossman, 2023), reiterating various points of his post and arguing that« The polyvagal hypotheses assume that RSA is a mammalian phenomenon, since Porges (2011) states “RSA has not been observed in reptiles.” I will here briefly document how each of these basic premises have been shown to be either untenable or highly implausible based on the available scientific literature. I will also argue that the polyvagal reliance upon RSA as equivalent to general vagal tone or even cardiac vagal tone is conceptually a category mistake (Ryle, 1949), confusing an approximate index (i.e., RSA) of a phenomenon (some general vagal process) with the phenomenon, itself. »

Porges strongly criticized Grossman’s use of the term «category mistake» (post and article), saying that Grossman «uses a straw man argument.» Of course, mammals have the dual advantage of a ventral vagal source and a myelinated vagal nerve. Porges has a point, but his hammer is aimed at the wrong nail. Grossman questioned «RSA, as equivalent to general vagal tone or even cardiac vagal tone» – another story. This article was part of a group of articles published in Biological Psychology, a special issue of ScienceDirect (2022), grouping articles by Grossman, Taylor, Berthoud, Neuhuber, Doody, Karemaker, and Shaffer. 

In December 2023, Grossman published Respiratory sinus arrhythmia (RSA), vagal tone and biobehavioral integration: Beyond parasympathetic function ResearchGate, again questioning the equivalence of RSA and vagal tone.

1.7.2

Edwin W. Taylor

After studying zoology and comparative animal physiology at the University of Southampton, Taylor was invited by Professor Otto Lowenstein to join the University of Birmingham (UK) in 1964. He remained there for the rest of his career, teaching animal biology and physiology. His work focused on the physiology (regulation of respiratory gas exchange, acid-base and water balance) of crustaceans and vertebrates, from fish to amphibians, reptiles, birds, and mammals. He has over 230 co-authored publications.

The major articles that Taylor has authored or co-authored related to Polyvagal Theory are:

Central Control of the Cardiovascular and Respiratory Systems and Their Interactions in Vertebrates (Taylor, 1999)

Toward understanding respiratory sinus arrhythmia: Relations to cardiac vagal tone, evolution and biobehavioral functions (Grossman, Taylor, 2007)

Autonomic control of cardiorespiratory interactions in fish, amphibians, and reptiles (Taylor, 2010) 

The phylogeny and ontogeny of autonomic control of the heart and cardiorespiratory interactions in vertebrates (Taylor, 2014)

An overview of the phylogeny of cardiorespiratory control in vertebrates with some reflections on the ‘Polyvagal Theory’ (Taylor, 2022). Taylor has also supported younger researchers, resulting in exciting studies that challenge the polyvagal thesis. You will often find Cleo Leite's name in his group.

Cardiorespiratory interactions previously identified as mammalian are present in the primitive lungfish (Monteiro, 2018) 

Respiratory sinus arrhythmia is a major component of heart rate variability in undisturbed, remotely monitored rattlesnakes, Crotalus durissus (Sanches, 2019).

1.7.3

Karemaker

His collaboration with Grossman began in 1991 with Prediction of tonic parasympathetic cardiac control using respiratory sinus arrhythmia: the need for respiratory control (Grossman, 1991). In The multibranched nerve: vagal function beyond heart rate variability (2022), he accurately describes the vagus, stating that «the dorsal motor nucleus is primarly concerned with processes such as the secretion of pancreatic enzymes and the promotion of peristalsis and digestion along the gastrointestinal tract.» The DMN is not significantly involved in the regulation of the heartbeat.  

In the same year, Karemaker and four other authors published An inherited sudden cardiac arrest syndrome may be based on primary myocardial and autonomic nervous system abnormalities (Verberne, 2022) and found that cardiac arrhythmias primarily cause sudden cardiac arrest (SCA). These may result from inherited cardiac ion channel dysfunction or cardiomyopathies. While Karemaker never directly criticizes PVT, his expertise and collaboration with Grossman are valuable.

1.7.4

Berntson & Cacioppo

Gary G. Berntson is also a name that has appeared prominently in discussions of heart rate variability for two decades. Heart rate variability: origins, methods, and interpretive caveats (Berntson,1997) results from the collaboration of 11 authors, including Paul Grossman, and Stephen Porges. He collaborates with Cacioppo and Grossman in Heart rate variability: origins, methods, and interpretive caveats (2007) and four other authors in Should heart rate variability be “corrected” for heart rate? Biological, quantitative, and interpretive considerations (De Geus, 2019). On the side of Berntson the names of Cacioppo and Norman will also appear frequently. Berntson, Cacioppo, and Grossman published in 2007 Whither vagal tone, which represents, in the same volume as the article by Taylor and Grossman, 2007), the first clear and differentiated criticism of the Polyvagal Theory. This article cites four publications by Cacioppo.

More about Berntson under Wikipedia.

1.7.5

Neuhuber & Berthoud

Winfried L. Neuhuber was at the Institute of Anatomy and Cell Biology, Friedrich-Alexander University, in Erlangen, Germany until 2017. Hans-Rudolf Berthoud, works in the Neurobiology of Nutrition & Metabolism Department, Pennington Biomedical Research Center, at the Louisiana State University. Neuhuber and Berthoud have published several remarkable articles over the years. Not only are they highly qualified, but they don’t hesitate to criticize the Polyvagal Theory. 

Functional and chemical anatomy of the afferent vagal system (Berthoud, 2000) is the first co-authored article to describe the vagal system, but without reference to the PVT. 

In Functional anatomy of the vagus system – emphasis on the somato-visceral interface (Neuhuber, 2021), the authors insist on the distinction between the compact nucleus ambiguus (AMB) and the external formation described by Bieger and Hopkins in 1987 (Bieger, 1987). Neuhuber and Berthoud further write that the ratio of cardiac DMX (dorsal) to AMB (ventral) preganglionic neurons varies between species: 80% (cats) and 60% (monkeys) are located in the ambiguus nucleus (Hopkins, 1998), (Taylor, 1999). In the shark ambiguus homolog, 45% of myelinated cardiac preganglionic neurons are in the ventral medulla, whereas 55% of unmyelinated neurons are in the dorsal DMX (Taylor, 2014). Thus, myelinated cardioinhibitory neurons are phylogenetically highly conserved and not a novel mammalian trait, as proposed by Porges (2001).

Bieger and Neuhuber have jointly published two follow-ups to the seminal (Bieger, Hopkins, 1987) article: Brainstem Neural Circuits and Mediators Regulating Swallowing (Bieger, 2006) and Brainstem Control of Deglutition: Brainstem Neural Circuits and Mediators Regulating Swallowing (Neuhuber, 2013). Their research overlaps with that of younger investigators (see next chapter) using optogenetic techniques, confirming earlier findings.

Functional Anatomy of the Vagus System: How Does the Polyvagal Theory Fit?(Neuhuber, 2022). In this recent article, according to the latest scientific knowledge, Neuhuber and Berthoud describe the vagal nerve. They start with a strong statement: “At first glance, the PVT, with its “old dorsal” and “new ventral vagus” subserving different behavioral tasks, provides a coherent and plausible framework for a “social engagement system” centered on the vagus. However, its basic phylogenetic and functional-anatomical tenets do not stand up to closer scrutiny,” they argue, point by point, in the following pages.

Critique of the Polyvagal Theory (Liem, Neuhuber, 2021) is a clear and accessible article that challenges the PVT.

1.7.6

Doody, Dinets and Burghardt

Fighting for reptiles

Another group of scientists was deeply disturbed by Porges' false claims about« asocial reptiles.» Early on, Burghardt wrote Social Behavior and Communication in Neonate Reptiles (Burghardt, 1977). In 2012, he and two other authors published Breaking the Social–Non-social Dichotomy: A Role for Reptiles in Vertebrate Social Behavior Research (Doody, J.S., 2012), which states: 

«Although social behavior in vertebrates spans a continuum from solitary to highly social, taxa are often dichotomized as either ‘social’ or ‘non-social.’ We argue that this social dichotomy is overly simplistic, neglects the diversity of vertebrate social systems, impedes our understanding of the evolution of social behavior, and perpetuates the erroneous belief that one group—the reptiles— is primarily ‘non-social.’ 

The Secret Social Lives of Reptiles by S. Doody, V. Dinets, and G. M. Burghardt (Doody, 2021) is an exciting book that synthesizes “a growing body of research on the social structures of reptiles. Covering species ranging from garter snakes to Komodo dragons, the authors explore the evolutionary origins of vertebrate social behavior and describe the diversity of social systems recorded for reptile taxa.”

In 2023, the same group wrote The Evolution of Sociality and the Polyvagal Theory (Doody, 2023), a scathing critique of the dichotomous polyvagal vision that pits social mammals against “asocial” reptiles: “The social-asocial dichotomy is overly simplistic, neglects the diversity of vertebrate social systems, hinders our understanding of the evolution of social behavior, and perpetuates the mistaken belief that one non-avian reptiles are incapable of complex social behavior.”

1.7.7

Around the autism

Porges' position on autism has drawn mixed reactions. In Autism Spectrum Disorder in Children Is Not Associated With Abnormal Autonomic Nervous System Function: Hypothesis and Theory (Barbier, 2022), the authors state that« a critical analysis of the data leads to the hypothesis that autonomic nervous system dysfunction is not a dominant feature of autism. Most children with ASD have normal parasympathetic baseline values and normal autonomic responses to social stimuli. The existing HRV and electrodermal data cannot lead to the conclusion of an over-excitation of the sympathetic nervous system.» 

Autonomic Responses to Head-Up Tilt Test in Children with Autism Spectrum Disorders (Bricout, 2018) challenges the assumption that children with ASD have autonomic dysfunction. « An emerging body of literature suggests that the link between these ASD symptoms and autonomic nervous system (ANS) dysfunction is related to sympathetic over-arousal, parasympathetic underactivity, or atypical inter-action of both systems (Althaus 2004),(Ming, 2005),(Bal, 2010),(Porges 2013).» « Our results showed that children with ASD did not have clinical signs of dysautonomia in response to a head-up tilt test.»

1.7.8

Internet Critical Voices

Critical voices are rare on the web, except in the academic world of Pubmed and ResearchGate.

R.I.P. Polyvagal Theory (Shin Shin Tang, 2021) and The Dark Side of Polyvagal Theory (Dunning, 2022).

Exploring the Controversy of Polyvagal Theory (including video recording), by Sophia Ansari, on The Lunch n’ Learn with Gian Ramos-Monserrate, MD.

Reptilian Brain Myth Is Still Alive and Kicking by Denise O’Leary

I also highly recommend Leah Benson's website, which has three influential articles on PVT and the Reptilian Brain.

On Medium (www.medium.com), you may find several interesting articles that I highly recommend:

  • James C. Coyne Guru Psychotherapist Unleashes Polyvagal Theory (…) , Alarming Things Believers in Trauma-Focused Care and Polyvagal Theory Do About Health Problems, and Polyvagal Theory: Science or Holy Scripture?, The Brilliant Marketing of Bessel van der Kolk and Stephen Porges and His Polyvagal Theory. James Coyne may be known for his “loud voice,” but he's well worth a read.

  • Max Pearl, The Problem with The Polyvagal Theory, points out that the term “polyvagal” as a misnomer and prefers “bivagal”. The rest is very instructive.

  • Olea Sylvestris, “Polyvagal theory” is pseudoscience. Here’s why. She begins with a statement: “I decided to publish this piece anonymously after some other critics of “polyvagal theory” warned me they had received personal attacks and threats in response to their criticism.” The article is very well written.

  • Trauma Geek, at first, seems to be an enthusiastic polyvagal advocate. However, she very accurately describes PVT issues related to autism in A Neurodivergent Review of the Safe and Sound Protocol and A Neurodiversity Paradigm Lens on Polyvagal Theory.

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