Anthony King writes:

You feel tension in the pit of your stomach as you begin your big public talk. You get butterflies as you wait for exam results. A mentor tells you to trust your gut feelings on a career decision. It’s no wonder ancient thinkers viewed the gut as the seat of emotions, or that a medieval physician even proposed that perception and our soul resided in our digestive organs. ‘Back in history we used to think the gut ruled everything,’ says microbiologist Brett Finlay at the University of British Columbia in Canada, ‘which I find amusing, now that we are getting back to that.’

Results from patients and animal models implicate gut microbes in Parkinson’s and Alzheimer’s diseases. Most Parkinson’s patients have a distinctive microbial signature in their gut. Put this microbiome into a Parkinson’s-like mouse and its condition deteriorates. Knock out the microbiome of Alzheimer’s or multiple sclerosis (MS) mice and their disease gets better, observes Howard Weiner, neurologist at Harvard: ‘That suggests the microbiome is participating in the disease.’

It is not only diseases. Mice without gut bacteria are more anxious. A 2011 study made timid mice into explorers by swapping their gut microbes with brave mice. ‘We’ve now shown unequivocally that the microbiome can affect a variety of different functions and activities of the brain,’ says Weiner. He believes such investigations can help us treat patients with Alzheimer’s and multiple sclerosis. Perhaps it’s not so surprising when the gut is home to 100 trillion bacteria, according to estimates, around 10 times the number of cells in the human body and they have evolved with us. [Continue reading…]