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.
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