Autism is a developmental disease characterized by a spectrum of symptoms ranging from decreased verbal skills and social withdrawal, to repetitive behavior and violent outbursts. Genetic analysis has yielded a few potentially interesting genes; however no clear linkage has been established, note experts. For this reason, it has been suggested that the etiology of autism may involve multiple causes. This, in large part, explains why so many different theories abound.

One such theory is that autism is caused or exacerbated by heavy metal poisoning. Environmentally acquired heavy metals including mercury, either through some causal contact or through vaccination, have been postulated as a major culprit.(Mercury is used as a preservative in some types of vaccinations.) Mercury is thought to be exerting its neurological effect on the brain. There are of course other areas of causation that are also critically important. But autism as a form of mercury poisoning is one area that we need to take seriously.

The standard treatment parents of autistic children commonly use has been to apply medically prescribed chelating agents in an attempt to extricate the mercury.

But the human body has an amazing ability to detoxify itself when given the proper nutrients.“One missing component in the treatment is the utilization of the body’s own detoxification mechanisms,”notes autism/probiotic expert Mark Brudnak, Ph.D., N.D., author of the The Probiotic Solution (Dragondoor Publications, 2003) and developer of probiotics formulas. In several articles in the journal Medical Hypotheses,Dr. Brudnak combines several potential mechanisms associated with autism to construct a theory that explains how the condition could develop and progress, and how probiotics can help.

“Arguably,” he says,“the largest detoxification component of the body—the endogenous enteric bacteria—are an enormous reservoir, which can be constantly and safely replenished.”

Piecing Together the Puzzle of Autism:  Linking the Digestive Tract to the Brain

Next, we went to Great Smokies Diagnostic Laboratory, which has been pioneering many different diagnostic tests that allow us to determine whether the gut flora of autistic children are in balance, and whether the intestinal tract suffers from excess permeability. Could there be a link between an imbalance of gut flora, intestinal permeability, and autism? (By permeability, we mean that the gut is leaky and is allowing undigested chemicals to pass directly through into the bloodstream. Some of these compounds are thought to be toxic and manifest their toxicity as autism symptoms.)

Childhood vaccinations have been implicated in the onset of autism, while diet has been implicated in its subsequent prognosis, Dr. Brudnak points out. A strong gut-brain connection is also apparent, with poor digestive function often appearing as a hallmark of the disorder.

According to the Great Smokies Connection newsletter:

“Dr. Brudnak speculates on the following chain of events. In early childhood, sensitivity to a vaccine, or a reaction to a mycobacterial infection, could disrupt pivotal molecular mechanisms that regulate how specific genes in the body switch ‘on’or ‘off’—what’s known as genetic expression. This may trigger malfunctioning of the immune and gastrointestinal systems, particularly in gut-associated lymphoid tissue,which Dr.Brudnak cites as ‘a major contributor to the pathological manifestations of autism.’

“When this happens, proteins are no longer properly broken down in the digestive tract. Cells in gut tissue die off prematurely, as the gut lining becomes ‘leaky’ and unable to repair itself. Compounds in the diet, like casein and gluten, normally kept at bay, may then permeate into the bloodstream. Their activated by-products, called exorphins, could act directly on the brain to trigger opioid-like effects associated with autistic symptoms.

“‘Such a scenario could explain why restoring healthy gut barrier function in autistic children is a treatment approach that ‘has met with a degree of success,’ Dr. Brudnak observes. Enzyme therapy (which improves the gut’s ability to break down proteins) and probiotics (supplementation with beneficial gut microbes that help repair the intestinal lining) have both produced positive clinical results in autistic children, he points out.

“In most cases symptoms of autism begin in early infancy. However, a subset of children appears to develop normally until a clear deterioration is observed. Many parents of children with ‘regressive’-onset autism have noted their children were given antibiotics immediately prior to the regression and that such use was followed by chronic diarrhea. This leads researchers to speculate that, in a subgroup of children, ‘disruption of indigenous gut flora might promote colonization by one or more neurotoxin-producing bacteria, contributing, at least in part, to their autistic symptomatology.’”

This line of thought stimulated recent research at the Section of Pediatric Gastroenterology and Nutrition, Rush Children’s Hospital, Rush Medical College, Chicago. To test this hypothesis, researchers took 11 children with regressive-onset autism for an intervention trial using a minimally absorbed oral antibiotic. Short-term improvement was noted using multiple pre- and post-therapy evaluations. “These results indicate that a possible gut flora-brain connection warrants further investigation” as a “meaningful prevention or treatment in a subset of children with autism.”

Now let’s take this even further and look at what happens to the gastrointestinal health of children with chronic gastroneurological-related disorders.

Chronic Immune Reactivity May Damage Intestine

“The challenge that many chronic disorders pose to modern medicine is that they often emerge as an interrelated tapestry of imbalances within the human body, rather than in response to a single, isolated cause,” notes the newsletter, “And autism may be a prime example of this.”

Many children with autism have chronic digestive problems. In fact, gastrointestinal symptoms in autistic children often first appear in conjunction with initial changes in emotion and behavior during the onset of autism, leading researchers to suspect a gut-brain connection.

A recent study reported in the American Journal of Gastroenterology lends strong support to this possible gut-brain link. Researchers performed a colonoscopy on 60 children with autistic spectrum disorders who also had symptoms such as stomach pain, constipation, bloating, and diarrhea. The autistic children had much greater evidence of intestinal lesions than healthy children or non-autistic children with similar digestive problems.

Over 90 percent of autistic children showed clinical evidence of chronic enterocolitis, such as lymphoid nodular hyperplasia, a sixfold greater rate than found in the non-autistic children with inflammatory bowel disease.

“The pathology seems to reflect a subtle new variant of inflammatory bowel disease…” the researchers concluded, a type of “autistic enterocolitis.” Enterocolitis is an inflammation of the mucous membrane of the intestine. Researchers are not sure what could be causing the condition in children with autism, although it usually arises from chronic immune reactivity. In autism, such immune responses might be triggered by substances in the diet (eg., opioid eptides), viral agents (such as measles virus), mercury, or other causes, the researchers speculated.

The opioid peptide theory was first presented to the medical world in 1979. Excess peptides (breakdown products of dietary proteins) act as opioids affecting neurotransmitters within the central nervous system.

In the normal course of events, proteins are digested in stages by enzymes; first to peptides (the intermediate compounds), then to smaller amino acid components, which are absorbed into blood capillaries in the gut mucosa. The larger peptides are generally unable to cross this membrane barrier, but when they do, they can act as opioids affecting neurotransmitters in the brain causing abnormal behaviors and/or activity. This theory suggests a higher percentage of these opioid peptides reach the brain in autistic children.

These incompletely digested peptides—known as exorphins, casomorphins, and gluteomorphins—usually come from milk proteins such as casein or from wheat (gluten) and are structurally similar to morphine. In experimental studies, they have been shown to exert a morphine-like neurological influence. The formation of excess peptides in the gut is possibly associated with sub-optimal enzyme activity or an insufficient supply of enzymes required to breakdown these peptides. This may be genetic in origin, or caused by other factors, such as enzyme inactivity secondary to nutritional deficiency, or by altered gut microflora

So if we repair the imbalance of beneficial bacterial organisms in the gut and the gut lining, we have a chance to help some of our children with autism.

Indeed, a report from a dietician at the Royal Free Hospital, London, and published in the Journal of Family Health Care recently discussed the link between autism and abnormal gut flora “and the use of probiotics and prebiotics in improving the integrity of the gut mucosa.”

“The gut-brain connection is now recognized as a basic tenet of physiology and medicine,” writes Eammonn M. M. Quigley, MD, in a related editorial,“ and examples of gastrointestinal involvement in a variety of neurological diseases are extensive.”

Andrew Wakefield and colleagues have raised the possibility that a subset of children with pervasive developmental disorder (which includes autism), particularly those with a history of developmental regression and chronic gastrointestinal symptoms, have a disregulated immune response to the measles antigen from the measles-mumps-rubella (MMR) vaccine. This has been suggested as a possible precipitating factor associated with intestinal abnormalities.

Did You Know—What is PDD?

Pervasive developmental disorder (PDD) is an umbrella term used to describe a group of disorders, including autistic disorder, which involve delayed development of communication and social-interaction skills and particular behavioral abnormalities. Although both genetic factors and environmental insults have been implicated in the pathogenesis of PDD, the underlying causes remain poorly understood.

Probiotics’ Role

Besides aiding repair of the gut lining and improving digestion,there is both anecdotal and clinical evidence that probiotics can help with detoxification, notes  recent report from Clinical Pearls, one of the nation’s premiere nutrition newsletters. “Aerobic organisms have been shown to readily detoxify mercury. . . According to the American Academy of Pediatrics, 90% of methylmercury is excreted through bile in the feces. . . .With large numbers of probiotic bacteria, mercury can effectively be driven toward expulsion. The administration of probiotics would prevent any recycling of toxic mercury. Mercury can cause an autoimmune response.”

Obviously,we don’t know all the answers yet, but use of probiotics appears to be a promising lead in helping children with this very difficult-to-treat condition. If your child’s autism is accompanied by gastrointestinal distress, the potential for probiotics to help might be further amplified.

This pivotal role of gut function in physical and emotional health is a central tenet of functional medicine and integrative treatment. Great Smokies Laboratories and others provide a variety of gastrointestinal assessments to help practitioners to detect and treat gut dysfunctions that may underlie or contribute to symptomatology in a diverse range of illnesses, including PDD and autism.