Autism affects about 1 in every 150 kids, but no one knows what causes it.

The leading theories for autism: Genetic, Vaccinations, Heavy Metal Toxicity, Chemical Exposure, Yeast/Candida, Gluten and Casein

Genetic

There was research done involving identical twins conducted at the MRC Child Psychiatry Unit at the Institute of Psychiatry in London.

It was found that if one identical twin had a autism then there was a 60% chance that the other would develop the condition. In contrast, for non-identical twins there was no increase at all in the chance of the second twin developing autism.

Suggests that autism have a definite genetic factor as being the identical twin of an autistic person markedly increases your chances of also having the disorder

However, it also suggest to us that autism may also involve significant environmental factors due to the fact that not every identical twin of an autistic child also develops the condition.

Research is now being conducted all over the world to determine specific genes that increase the likelihood of someone developing autism.

A group known as the International Molecular Genetic Study of Autism Consortium, which includes clinicians and researchers from the USA, UK, France, the Netherlands, Denmark, Italy, and Greece, has pinpointed four chromosomes which they believe play critical roles in autism.

The chromosomes they identified are numbers 2, 7, 16 and 17.

These findings are further demonstrated by research showing dyslexia patients also have abnormalities on these chromosomes.

Vaccinations

It has been proposed that the combined measles, mumps and rubella vaccine (MMR) may be a causative factor in autism.

The researchers reviewed reports of children with bowel disorders and regressive developmental disorders, mostly autism, and suggested that the MMR vaccination may have been one possible environmental trigger that led to intestinal abnormalities, resulting in impaired intestinal function and developmental regression. However, this was based on a very small scale.

Research into gut ecology and its role in illness is increasingly showing the link between disturbed gut microflora and symptoms distant from the gastrointestinal tract. Examples of this are multiple studies providing evidence for the role of Klebsiella pneumoniae in ankylosing spondylitis and Proteus sp in rheumatoid arthritis.

Given this, it is entirely plausible that behavioral symptoms could precede overt bowel symptoms in autistic children even though the root cause is a bowel disturbance.

Given that the MMR vaccine subjects the immune system to three different antigens at once it is a possibility that the child's immune system, while dealing with these becomes more susceptible to pathogenic changes in the bacterial composition of the intestines or causes other detrimental immunological or neurological changes not yet identified.

Yeast/Candida

It was found that people suffering from autism consistently have elevated levels of certain organic acids in their urine.

It was found that a large percentage of autistic children have significant immune dysfunction and this may include a genetic weakness that impairs the body's ability to kill yeast as well as deficiencies of IgG and IgA. IgA antibodies are responsible for killing pathogens in the gastrointestinal tract. It is believed that most of the tartaric acid is produced by yeast in the GI tract as Nystatin, which is not absorbed into the body, has been successful in returning tartaric acid levels to normal.

The debate over the role of intestinal yeast overgrowth in chronic illness has been going on for decades due to the lack of a definitive marker that can be used reliably to detect the presence of increased growth of yeast in the intestines.

Recent research has strongly suggested that D-arabinitol may be a candidate for this definitive marker (9, 10). D-arabinitol is a 'sugar alcohol' produced by yeast when they feed on a sugar called arabinose.

Circumstantial evidence that also points in favour of a role for yeast in autism is the fact that the increase in these illnesses has paralleled the increase in the use of antibiotics which tend to wipe out beneficial bacteria in the gut allowing yeast such as Candida to proliferate.

Heavy Metal Toxicity

Another finding in autistic children is a higher level of heavy metals than normal. One source of mercury exposure in early life is through vaccinations. Thimerosal is a preservative used in many vaccinations to prevent contamination. Thimerosal is 49.6% mercury by weight.

A study in March 2006 showed that in the 4 years following the recommended removal of thimerosal from childrens vaccines, exposure of children to this toxin was reduced to almost zero, and most importantly, new cases of autism actually began to decrease.

Levels of mercury can be determined upon hair analysis. Using thimerosal containing vaccines would result in a hair concentration of greater than 1ppm (parts per million) of mercury for up to 365 days with various peaks during that period. 1ppm is the safe limit set by the Environmental Protection Agency (EPA).

Research at the UCLA Medical Center in California has also shown that Thimerosal (when bound to human albumin protein) triggers an immune system reaction in autistic children, resulting in the production of antibodies. This indicates a possible autoimmune reaction as the immune system could react against any of the child's own tissues that happen to have Thimerosal bound to them.

Exposure to low levels of mercury during critical stages of development has been associated with neurological disorders in children, including ADD, learning difficulties, and speech delays, the predicted hair Hg (mercury) concentration resulting from childhood immunizations is cause for concern.

It was found that in mice at least, thimerosal can disrupt the immune system. The researchers in this study looked at dendritic cells which can be described as messengers within the immune system. These cells take up invaders such as bacteria, viruses and other antigens such as vaccine ingredients and process them. They then migrate to the lymph nodes to present their information to other immune cells, which can activate a systemic immune response. These dendritic cells are highly sensitive to thimerosal. With low concentrations of thimerosal, an inflammatory response occurs and with higher concentrations the cell is actually killed. These reactions could lead to any number of unwanted, and uncontrolled, effects within the immune system.

Autistic children often show signs of immunological dysfunction with allergies, gut disorders and frequent infections being common. The effects of thimerosal on the immune system, that this study demonstrates, provides one possible explanation of why this is the case.

Other possible sources of heavy metal exposure are contaminated food and water supplies. Fish is particularly associated with contamination as oceanic pollution becomes more concentrated as it moves up the food chain to predatory fish.

Chemical Exposure

Environmental exposure to mercury, pesticides and other contaminants during early childhood development could easily alter the normal function of a child's systems

The UC Davis Institute will conduct research using a large sample of 2000 autistic children and will look at possible chemicals and levels of these chemicals that the children were exposed to during early childhood to see if there is a correlation.

Researchers are working on the assumption that there is a genetic susceptibility to autism in a proportion of children but there may be an environmental factor that has to be present during their early years that "pushes their nervous system over the edge into autism".

The study will also assess blood levels of environmental toxins in autistic subjects compared to healthy subjects and will aim to find out the impact of exposures on the brain's ability to send signals and on cell growth in the nervous system, as well as identify the underlying biochemical process

Toxic contaminants are linked to increases in the prevalence of attention deficit hyperactivity disorder, autism, and associated neurodevelopment and behavioral problems in developed countries. Particular note is made of the high sensitivity of the unborn foetus to thyroid disturbance and the many chemicals in common use that could interfere with the thyroid function of mothers.

Gluten and Casein

Gluten is a protein found in grains such as wheat, rye, oats and barley. Casein is a milk protein found in the milk of all the animals whose milk humans in the western world regularly consume, cows milk, sheep's milk and goats milk.

Autistic people often have gut problems including frequent gut dysbiosis. As a result, digestion is impaired resulting in the incomplete digestion of gluten and casein. What is disturbing is that when not properly digested, gluten and casein can end up as peptides (protein building blocks) with a chemical structure that resembles that of the opiates (opium, morphine and heroin). There is a significant, and growing, amount of published research showing that gluteomorphin and casomorphin (the offending peptides) have been detected in the urine of autistic children . These peptides can pass easily through the blood-brain barrier and interfere with the functioning of neurotransmitters such as Sheraton and dopamine, just as the opiate drugs do. As a result the patient suffers a range of neurological and psychological symptoms.

Investigators at the UCLA Medical Center in California have also shown that both gluten and casein peptides trigger an immune response in children with autism, resulting in the production of antibodies to these substances (17).

As a result of these findings, the gluten and casein free diet (GFCF) has been developed. By avoiding both gluten and casein, both children and adults with autism can be helped a lot.

Junhao