5 February 2022 | New Scientist | 49A deeper understanding of the complexities
of interoception will also help to inform future
treatments. Khalsa is working on a way to
explore gut sensitivity in eating disorders and
how it manifests in the brain. He has designed
a vibrating capsule that can be swallowed and
used as a probe to measure gut sensitivity.
Combined with electroencephalography,
which measures brain activity using sensors
on the scalp, this will allow mapping of
possible differences in the brain’s response
to gut sensation.
A test on 40 healthy volunteers has so far
shown that their perception of the probe grew
as the intensity of vibrations increased, which
correlated with increased activity in parts of the
brain that are thought to be a gastric detection
network. Khalsa is working on a trial in people
who are hospitalised with anorexia to see if
differences in their gut sensitivity predict their
chances of recovery over the long term. The
ultimate end point would be a way to intervene
in this process to improve chances of recovery.
Khalsa hopes that we will eventually
understand interoception so well that we can
“go through the process stepwise, identifying
where in the nervous system is the issue”,
he says. When it is easier to identify where
problems arise, new targets for treatments will
follow. And with more knowledge of how to
intervene for ourselves comes the possibility
of using forms of self-care that improve our
mental health – whether that is a session in a
floatation tank or doing star jumps to get used
to how your heart feels when it is pumping
hard and how to use deep breaths to calm
it down afterwards.
While it is early days for evidence-based
interoceptive treatments, Garfinkel believes
that the time for ignoring the body’s role in
mental health is well and truly over. “Mental
health conditions, especially those with some
degree of emotional disturbance, have their
origin in aberrant interoceptive mechanisms
and any treatment that targets the body has
the potential to help treat these conditions.
I honestly believe it’s a potential revolution
in mental health treatments,” she says. ❚Counter-intuitively, it seems to be
possible to use the fear-boosting
effects of a rapid heartbeat (see
main story) to help tackle severe
phobias. These are often treated
with exposure therapy, in which
a person is gradually confronted
with a more intense version of their
greatest fear while they learn that
it is safe to experience it.
In one study, people with
arachnophobia were shown images
of spiders as their heart contracted.
They became able to tolerate spiders
sooner than those who were shown
an image that was timed with the
relaxation of the heart. Showing
people spiders when their fear
system was most heightened, but
in a controlled setting, seemed to
supercharge the exposure therapy,
allowing them to recover emotional
control more quickly.SPIDEY
SENSES
The extreme bendiness of the joints is
caused by a more flexible form of collagen, but
collagen is also found in blood vessels. Laxer
collagen here causes blood to pool in the lower
legs, which forces the heart to beat faster to
maintain blood pressure. This racing heart can
be interpreted as anxiety, even when there is
no obvious cause for concern. Jessica Eccles,
also at the University of Sussex, is now
investigating if training people to interpret
these signals differently may bring some relief.
More direct ways to calm the body are also
being developed. The descending branch of
the vagus nerve is part of the parasympathetic
nervous system, which returns the body’s
arousal back to a calm baseline after stress.
Electrically stimulating the vagus nerve via
an implant in the neck has been shown to
reduce symptoms of anxiety and depression
in people with a clinical diagnosis of these
conditions. Non-invasive ways to stimulate
the nerve are now in the works, although
there is little hard evidence so far that this
non-implanted method works for mental
health conditions.
RE
UTER
S/FRA
NCIS^ MAS
CARE
NHAS
VIAALAMYFloatation therapy
can help to quieten
certain body signalsCaroline Williams is a science
journalist and the author of
Move! The new science of
body over mind.