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How the Digestive System Affects Autism

The finding that metabolism and genes in autism may not be irreversibly damaged but can actually be altered by compounds produced from bacteria, provides an important link between the gut and brain in autism, and validates the stories that families have been telling us.

Current autism rates have skyrocketed nearly 150-fold in the last half century, and all of us are justifiably concerned. We are told what does not cause autism, but it is unclear what does cause or contribute to this devastating condition.

Furthermore, despite incredible modern medical advances, in many cases we are sicker than ever before. Parallel rises in infections and chronic diseases including obesity, some cancers, immunological disorders and other neurological conditions are seen. These, along with autism, will decimate our health care systems, our families, and indeed many societies. This is sadly paralleled in developing nations with fragile economies, who are also seeing this alarming trend as they adopt the Western way of life. Why is this happening? What can we do about it?

The cause of this alarming increase may lie in a most unexpected place, the trillions of microbes that inhabit our digestive tracts.

As director of a Canadian research group examining the role of digestive system links to autism, I was honoured to present at a recent Nobel Forum "The Gut in Focus" held at Sweden's famed Karolinksa Institute and chaired by Dr. Tore Midtvedt, a pioneer and world authority on the role that human microbes play in health and disease.

The symposium presented increasing evidence that this complex microbial ecosystem, called the "microbiome," outnumbering human cells 10 to one, co-evolved with us and are mostly present for our benefit. However, these microbes have become recently altered as a consequence of modern society, through the longstanding overuse of antibiotics, disinfectants, C section delivery, and even diet. It appears that these bacterial alterations are affecting human health, and are in part responsible for the alarming increases of many diseases, in particular, autism.

Extensive epidemiological studies were presented by Drs. Dennis Lang and Merette Eggesbo, who followed infants and their bacteria from populations in Norway and other developed and emerging countries worldwide. Remarkably, they found altered bacterial populations early in life could predict future health and disease, including neurodevelopmental disorders. Studies presented by Dr. Rochellys Diaz- Heijtz showed that early alteration of bacterial populations or antibiotic exposure in rodents can have profound effects on brain development and behavior.

The role of the microbiome in autism was extensively covered. First reported over half a century ago and occurring in about 1 in 10,000 individuals, autism's presentation of impaired language, repetitive behaviours, social deficits and self-injury has now increased to one in 68 individuals. This growth cannot be solely attributed to genetic alterations and increased surveillance, where most of the funding has concentrated. The further finding of varying severities or even absence of autism in genetically identical twins must involve some contribution from our changing environment.

The practice of medicine is centred on patient history. For decades, parents kept telling us their children have peculiar dietary cravings, gut and digestive problems, "good days and bad days", and some appeared to have regressed after seemingly normal development. Furthermore, studies report early antibiotic exposure, unique gut bacterial populations, and immune and metabolic findings in autism, but how they related to autism or autism behaviors was unclear.

Our research at the Kilee Patchell-Evans Autism Research Group, Western University, Canada have shown that excesses of compounds known as short chain fatty acids, which are produced when our gut bacteria ferment carbohydrates obtained from our diet, affect our brain and behaviour, in part by altering brain development, inflammation, energy utilization and fat metabolism. They can even turn on and off autism related genes.

Our recent work in collaboration with Dr. Richard Frye at Arkansas Children's Hospital, showed that overproduction of these compounds alter our body's energy and fat metabolism, by affecting our mitochondria, the energy store house within cells. Our studies with Dr. Bistra Nankova of New York Medical College showed that these fatty acid products of bacteria can also act as "switches" for many autism associated genes, known to affect neural development and transmission, that traditional genetic studies have felt were the sole culprit of the disorder.

The finding that metabolism and genes in autism may not be irreversibly damaged but can actually be altered by compounds produced from bacteria, provides an important link between the gut and brain in autism, and validates the stories that families have been telling us. These unique bacteria and blood markers will be useful for screening children for early behavioral intervention, but also herald novel treatments such as carnitine supplementation, which improves brain energy metabolism, as well as other proposed treatments including dietary changes and even microbiome repair. Presentations by Dr. Elizabeth Norin and others indeed showed evidence that "restoration" of the gut microbiome in a number of conditions is safe and a viable treatment, and discussed the possibility of executing this in autism.

This conference holds a cautionary note that many of the benefits of industrialised societies and medical practices, although life-saving, must be used judiciously and may have enormous consequences to future world health. We are not alone, our bacteria appear to be influencing who we are and even how we behave and they may in a sense be telling us our environment is changing.

A decade ago our research started with families' tragic stories and a chance meeting with David Patchell-Evans. His daughter had been diagnosed with autism at age three and information at the time was scarce. His determination to help others led to the formation of The Kilee Patchell-Evans Autism Research Group. To date Patchell-Evans, CEO of GoodLife Fitness Clubs, has donated over $5 million in research funding. He has received the Canadian Medical Association's Medal of Honour, and a Doctor of Laws, honoris causa from Western University for his devotion to persons with autism and their families.

I am immensely grateful for his support and I want families to know that there is real scientific progress in this field, and gut microbes are becoming the game changer in this devastating condition.


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