Over a lot of years of professional life, I have seen some concepts become popularized, reinterpreted, and generalized beyond all meaning or expectation. One of these concepts was attachment, a rather technical term to begin with but now the explanation of all sorts of problems in self-help discussions. Another is parental alienation, once a term applied to a rare occurrence in divorced families, now a weapon brandished regularly in family courts.
In my pessimistic way, I have been wondering what would be the next wave of misinterpretation—the next concept that will be made the explanation for too much and the foundation of treatments without any basis in evidence. And I think I have found the latest thing: the vagus nerve.
Of course, there really is a vagus nerve. It’s the tenth of the 12 cranial nerves and helps to regulate the heartbeat as well as having other similar functions. Some decades ago, Steven Porges created “polyvagal theory” (PVT), a psychological approach that based emotional and other human functioning on vagus nerve activity. PVT makes a number of assumptions about the evolution of the human nervous system and posits that when threat is felt, human beings revert to an evolutionarily older type of brain function. This is reflected in vagal activity as known through measurement of an aspect of the heartbeat. Grossman and Taylor in 2007 criticized this view thoroughly, noting both misunderstandings of the evolutionary background and the functioning of the nervous system.
As so often happens when simplistic approaches to the human nervous system are popularized, the claims of PVT soon morphed into treatment plans. The assumption was that if the vagus nerve underlies emotional functioning, anything that affects the activity of the vagus can also influence emotional functioning. In the parental alienation treatment program Transitioning Families, for example, therapists ask clients to “map the autonomic nervous system” by imagining a ladder and climbing it until they reach a place of safety at the top, where a comfortable state of vagal activity is thought to be. Deep breathing is also used, as it is thought be this group of therapists that it stimulates the vagus to reach a calm state. There is no empirical evidence that the vagus is influenced in this way or that there are emotional benefits to the practice.
On her website, one Dr. Arielle Schwartz advises similar techniques that are directed toward affecting vagal activity with the goal od improving mood and functioning. She says, “The vagus nerve passes though by [sic] the vocal cords and the inner ear and the vibrations of humming is a free and easy way to influence your nervous system states”. In addition to humming, she recommends diaphragmatic or “belly” breathing and slowing of the breath, which she proposes as a way to stimulate the vagus nerve.
Schwartz also suggests the Valsalva maneuver, a way of attempting to breathe out even though mouth and nose are closed , as a way to increase pressure in the chest cavity and vagal tone. She believes that the “diving reflex” can be stimulated by splashing your face with cold water, putting a bag of ice on your face, or holding lukewarm water in your mouth. She does not describe how these practices are supposed to affect the vagus nerve, but the reflex does slow heartrate and oxygen use.
Some readers will recognize the breathing and humming techniques as part of yoga and similar practices. They are not directly harmful and may be enjoyable. Indirect harms are possible if an individual puts resources of time and money into methods with neither empirical or theoretical evidence of benefit.
The Valsalva maneuver can be used to treat a too-rapid heartbeat. It should not be used by people with high blood pressure or risk of a stroke. Triggering the diving reflex can be problematic for people with heart problems or a slow heartbeat. As was the case for breathing and humming, indirect harms may come from expenditure of resources for methods that may have no real effect beyond a few minutes.
PVT methods seem to be appearing on the Internet as the newest of the new. However, I remember reading a newspaper medical advice column when I was a young teenager in the mid-1950s.—it spoke of “belly breathing” and advocated the same sorts of techniques as PVT approaches, similarly without supportive empirical evidence. The PVT-related concept of the “enteric brain” and its functions has been posed for decades by the Meridian Institute of Virginia Beach; this institute is associated with the writings of Edgar Cayce, the American “clairvoyant”.
There seems to be no end to the ways people can suggest simple solutions to complex mental health problems. The popularization of PVT seems to be the most recent of these, but it won’t be the last.