That anxiety may be in your gut, not in your head

May 17, 2011, McMaster University

For the first time, researchers at McMaster University have conclusive evidence that bacteria residing in the gut influence brain chemistry and behaviour.

The findings are important because several common types of , including , 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 .

"The exciting results provide stimulus for further investigating a microbial component to the causation of behavioural illnesses," said Stephen Collins, professor of medicine and associate dean research, Michael G. School of Medicine. Collins and Premysl Bercik, assistant professor of medicine, undertook the research in the Farncombe Family Digestive Health Research Institute.

The research appears in the online edition of the journal Gastroenterology.

For each person, the gut is home to about 1,000 trillium with which we live in harmony. These bacteria perform a number of functions vital to health: They harvest energy from the diet, protect against infections and provide nutrition to cells in the gut. Any disruption can result in life-threatening conditions, such as antibiotic-induced colitis from infection with the "superbug" Clostridium difficile.

Working with healthy adult mice, the researchers showed that disrupting the normal bacterial content of the gut with antibiotics produced changes in behaviour; the mice became less cautious or anxious. This change was accompanied by an increase in (BDNF), which has been linked, to depression and anxiety.

When oral antibiotics were discontinued, bacteria in the gut returned to normal. "This was accompanied by restoration of normal behaviour and ," Collins said.

To confirm that bacteria can influence behaviour, the researchers colonized germ-free mice with bacteria taken from mice with a different behavioural pattern. They found that when germ-free mice with a genetic background associated with passive behaviour were colonized with bacteria from mice with higher exploratory behaviour, 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 behaviour.

While previous research has focused on the role bacteria play in brain development early in life, Collins said this latest research indicates that while many factors determine behaviour, the nature and stability of bacteria in the gut appear to influence behaviour and any disruption , from antibiotics or infection, might produce changes in behaviour.

Bercik said that these results lay the foundation for investigating the therapeutic potential of probiotic bacteria and their products in the treatment of behavioural disorders, particularly those associated with gastrointestinal conditions such as irritable bowel syndrome.

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7 comments

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Mungaman
not rated yet May 17, 2011
There are 1000 flowering plants in my gut?
Ionian
3 / 5 (2) May 17, 2011
change "trillium bacteria" to "trillion bacteria"
Mungaman
not rated yet May 17, 2011
Uh, yes Ionian... that's what I was driving at.
gmurphy
not rated yet May 17, 2011
Never mind trillium, the proper term is 'hella many' :-P
plasticpower
not rated yet May 17, 2011
I always suspected this, cool article.
RobertKarlStonjek
not rated yet May 18, 2011
I wonder what effect the change to vegetarianism would have ?
HannesAlfven
not rated yet May 22, 2011
This is 100% in line with firsthand experience. My girlfriend has extreme anxiety, which perfectly cycles with a rash which covers many parts of her body. The rash and anxiety's sudden simultaneous appearance appeared to coincide twice in her life: with an anxiety-drug called Effexor the first time, and the second time with Prozac.

When growing plants organically in real, outdoor soil, organic growers are well-versed in the fact that many synthetic chemicals can kill the natural, living bacteria which feed plants. Thus, organic growers are very cautious with the amounts of synthetic fertilizers which they ever use. Many stick exclusively to organic teas.

By extending the analogy, one has to at least suspect that bacteria create electricity in the human just as they do in plants. In plants, the bacteria are in the soil, whereas in humans, it's in the gut.

Fantastic find. This suggests, for the first time, a way out of this nightmare, which has persisted for about a year now.

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