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 New
study finds that anxiety may
originate in your gut, not in your
head
by Tony Isaacs
(The
Best Years in Life) We're all
familiar with the term "gut
feeling". As it turns out, the term
may be more apt than we realize. In
recent years, research has
increasingly identified the role the
gut can have on mood and behavior,
leading many scientists to refer to
the gut as the "second brain". Now,
for the first time, researchers have
found conclusive evidence that
conditions such as anxiety can
originate in the gut instead of the
brain.
In a study just published in the
journal Gastroenterology,
researchers at McMaster University
found that bacteria residing in the
gut influence brain chemistry and
behavior. The research is important
because several common types of
gastrointestinal disease are
frequently associated with anxiety
or depression. In addition there has
been speculation that some
psychiatric disorders, such as late
onset autism, may be associated with
an abnormal bacterial content in the
gut.
"The exciting results provide
stimulus for further investigating a
microbial component to the causation
of behavioral illnesses," said
Stephen Collins, professor of
medicine and associate dean of
research at McMaster's Michael G.
DeGroote School of Medicine. Collins
and Premysl Bercik, assistant
professor of medicine, conducted the
research in the Farncombe Family
Digestive Health Research Institute.
Working with healthy adult mice, the
researchers found that disrupting
the normal bacterial content of the
gut with antibiotics produced
changes in behavior; the mice became
less cautious or anxious. This
change was accompanied by an
increase in brain derived
neurotrophic factor (BDNF), which
has been linked to depression and
anxiety.
When oral antibiotics were
discontinued, bacteria in the gut
returned to normal and Collins
reported that there was "restoration
of normal behavior and brain
chemistry."
To confirm that bacteria can
influence behavior, the researchers
colonized germ-free mice with
bacteria taken from mice with a
different behavioral pattern. They
found that when germ-free mice with
a genetic background associated with
passive behavior were colonized with
bacteria from mice with higher
exploratory behavior, they became
more active and daring. Similarly,
normally active mice became more
passive after receiving bacteria
from mice whose genetic background
is associated with passive behavior.
Collins said that his team's
research indicates that while many
factors determine behavior, the
nature and stability of bacteria in
the gut appear to influence behavior
and disruptions from antibiotics or
infections might produce changes in
behavior. Bercik said that these
results lay the foundation for
investigating the therapeutic use of
probiotic bacteria in the treatment
of behavioral disorders,
particularly those associated with
gastrointestinal conditions.
The gut is home to about 1,000
trillion bacteria. The gut also
contains around 100 million nerve
cells (neurons), more than in either
the spinal cord or the peripheral
nervous system. This multitude of
neurons in the enteric nervous
system enables us to "feel" the
inner world of our gut and its
contents. Neurons in the gut also
use serotonin to signal back to the
brain - and 95% of all serotonin in
the body is in the gut. About 90
percent of the fibers in the primary
visceral nerve, the vagus, carry
information from the gut to the
brain.
Generally when people think of "gut
feelings" they are thinking about
instinctive-like reactions such as
the "butterflies" or "hollow
feelings" one may get due to fear,
bad news or an upcoming daunting
task. Now it is apparent that other
serious conditions may originate at
least partially in the gut.
Maintaining a healthy digestive
system, including a healthy
intestinal flora mix, could be a key
in helping prevent and control such
conditions.
Note: This author does not
approve of the inhumane use of
animals for laboratory experiments.
Sources included:
http://www.sciencedaily.com/releases/2011/05/110517110315.htm
http://www.scientificamerican.com/article.cfm?id=gut-second-brain
http://www.psychologytoday.com/articles/199905/our-second-brain-the-stomach
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