Autism Spectrum Disorders (ASDs) officially belong to a group of illnesses known as 'developmental disabilities'. They are characterized by problems with social and communication skills of varying degrees. Autistic people also commonly display unusual ways of learning, reacting to different sensations and paying attention. Sufferers also tend to repeat certain behaviors and have difficulties when required to change their usual daily activities. ASDs are commonly said to start in childhood and last for the persons whole life ,but as you will see below, there are many new theories as to the cause(s) of these disorders and many offer the hope of effective treatments.
The following definition of Autism is taken from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM IV), which is used to diagnose Autism:
DIAGNOSTIC CRITERIA FOR 299.00 AUTISTIC DISORDER
A. A total of six (or more) items from (1), (2), and (3), with at least two from (1), and one each from (2) and (3)
(1) qualitative impairment in social interaction, as manifested by at least two of the following:
a) marked impairments in the use of multiple nonverbal behaviors such as eye-to-eye gaze, facial expression, body posture, and gestures to regulate social interaction
b) failure to develop peer relationships appropriate to developmental level
c) a lack of spontaneous seeking to share enjoyment, interests, or achievements with other people, (e.g., by a lack of showing, bringing, or pointing out objects of interest to other people)
d) lack of social or emotional reciprocity ( note: in the description, it gives the following as examples: not actively participating in simple social play or games, preferring solitary activities, or involving others in activities only as tools or "mechanical" aids )
(2) qualitative impairments in communication as manifested by at least one of the following:
a) delay in, or total lack of, the development of spoken language (not accompanied by an attempt to compensate through alternative modes of communication such as gesture or mime)
b) in individuals with adequate speech, marked impairment in the ability to initiate or sustain a conversation with others
c) stereotyped and repetitive use of language or idiosyncratic language
d) lack of varied, spontaneous make-believe play or social imitative play appropriate to developmental level
(3) restricted repetitive and stereotyped patterns of behavior, interests and activities, as manifested by at least two of the following:
a) encompassing preoccupation with one or more stereotyped and restricted patterns of interest that is abnormal either in intensity or focus
b) apparently inflexible adherence to specific, nonfunctional routines or rituals
c) stereotyped and repetitive motor mannerisms (e.g hand or finger flapping or twisting, or complex whole-body movements)
d) persistent preoccupation with parts of objects
B. Delays or abnormal functioning in at least one of the following areas, with onset prior to age 3 years:
(1) social interaction
(2) language as used in social communication
(3) symbolic or imaginative play
C. The disturbance is not better accounted for by Rett's Disorder or Childhood Disintegrative Disorder
(Rett's Disorder and Childhood Disintegrative Disorder belong to a group of illnesses called 'pervasive developmental disorders', as do Autism Spectrum Disorders)
Conditions Included in Autistic Spectrum Disorders
Autistic Spectrum Disorders include autistic disorder, pervasive developmental disorder - not otherwise specified (PDD-NOS), and Asperger's syndrome. The definition quoted above is specifically for autistic disorder but both PPD-NOS and Asperger's disorder have some of the same symptoms, but they differ in terms of when the symptoms start, how fast they appear, how severe they are, and their exact nature.
Diagnosing Autism Spectrum Disorders
Early detection of autism is considered essential for the effective use of many behavioural therapies. Various screening techniques have been developed utilizing questionnaies, interviews, and clinical observation. A combination of these methods is usually used.
A number of different questionnaies have been created to help doctors and researchers diagnose autism in children. The CHAT (Checklist for Autism in Toddlers) is considered to be a HIGHLY accurate and simple autism screening tool for early autism diagnosis. Research supporting the CHAT has been published in the British Journal of Psychiatry. Studies have found that the CHAT is 85% accurate in diagnosing children with autism and 100% accurate in diagnosing a developmental delay in general. The CHAT can be used for children 18 months old or older.
Recently a modified CHAT (M-CHAT) has been developed to increase accuracy even further.
Possible Causes of Autism
At present, no definitive cause has been identified for autism. Both genetic and environmental factors are being studied as possible causative factors. Studies carried out throughout the developed world have found that around 6 in every 1000 children have at least one ASD. A US government report published in January 2003 stated that incidence had increased ten fold in only 10 years. There is also evidence that this number is still increasing and that cases appear in clusters, both of which tend to lend weight to the theory that ASDs involve a significant environmental factor. On the other hand , with regards to increasing numbers of cases, it may just be that doctors are more aware of these illnesses and are better able to diagnose them but this wouldn't seem to account for such a large increase. It should be stressed that it is known that ASDs are not caused by parental actions.
Below are the leading theories for the cause(s) of Autistic Spectrum Disorders:
One of the strongest indicators of the role that genetics plays in Autism Spectrum Disorders comes from research involving identical twins conducted at the MRC Child Psychiatry Unit at the Institute of Psychiatry in London (1). The researchers found that if one identical twin had a autism then there was a 60% chance that the other would develop the condition. This was in contrast to non-identical twins where there was no increase at all in the chance of the second twin developing autism. Even when the criteria were expanded to include the other ASD's a similar correlation was observed. This study suggests that ASDs 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 ASDs 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. The evidence for involvement of chromosomes 2 and 7 is particularly strong as these had also been previously identified by other independent researchers (2,3,4,5). Chromosome 7 is known to be associated with many language disorders and chromosome 2 plays an important role in early brain development. These findings are further demonstrated by research showing dyslexia patients also have abnormalities on these chromosomes (6). This is not surprising as dyslexia also produces deficits in learning ability and information processing in the brain.
These findings are based on a study involving 150 autistic children. A further study involving up to 500 people is now underway that should provide an even better picture of genetic involvement in ASDs.
In February 2008, the US government conceded that vaccines had caused an autism-inducing reaction in one little girl, Hannah Poling. At the time most experts stated that her underlying condition, a mitochondrial disorder, was very rare and so the case had no implications for other children with autism. The United Mitochondrial Disease Foundation (UMDF) however has said that mitochondrial disorders are at "the core of many well known diseases and chronic illnesses, such as Alzheimer's disease, Parkinson's disease and autism spectrum disorders." Subsequently the Foundation published research demonstrating that at least one in 200 healthy humans "harbors a pathogenic mitochondrial mutation that potentially causes disease." The study was published in the American Journal of Human Genetics (21).
Aside from vaccines now being implicated in triggering mitochondrial dysfunction and possibly autism as a result, it has been proposed that the combined measles, mumps and rubella vaccine (MMR) may be a causative factor in autism. This has been a subject of hot debate however. The study that brought this to the attention of the public was conducted in the UK in 1998 (Wakefield et al)(7).
See the full research abstract here.
The researchers reviewed reports of children with bowel disorders and regressive developmental disorders, mostly autism. The researchers 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. This hypothesis was based on 12 children. In nine of the cases, the child's parents and/or pediatrician felt that the MMR vaccine had contributed to the behavioral problems of the children in the study.
Since this study was published many other researchers have questioned its validity. It should be noted that this criticism only refers to a link between MMR and autism. The research by Dr. Wakefield demonstrated a valid link between autism and gastrointestinal disease with findings of chronic intestinal inflammation in 11 of the 12 children and reactive ileal lymphoid hyperplasia in 7. Haemoglobin and serum IgA (an antibody produced by the immune system) were found to be low in 4 of 12 children. Finally, methylmalonic acid was found to be consistently high, this is a strong indicator of vitamin B12 deficiency. None of these other findings have been disputed and indicate a need for further study in these areas.
One valid criticism of the MMR connection is that it was a very small study, having only 12 subjects. However this doesn't negate the findings entirely, it just means that larger studies should be conducted in this area. Another major criticism is that in at least 4 of the 12 cases, behavioral symptoms preceded the onset of the bowel disorder and thus the line of cause and effect between MMR vaccination and autism, is broken.
From an environmental illness perspective the criticism itself seems simplistic. 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. Accordingly this possibility should not be dismissed out of hand.
Bowel problems are are common finding in all environmental illnesses as any sufferer will reveal. Studies looking for changes in gut microflora using stool, urine and blood testing have also confirmed a high rate of abnormality in environmental illness patients (see Eaton et al). It is also widely accepted that these illnesses have a prominent immune dysfunction component. Studies have also shown that patients with compromised immune systems have a high incidence of abnormal gut microflora. 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.
Indeed, an increasing number of medical professionals are voicing concern about the immunological changes caused by vaccinations, especially regarding multiple vaccinations over a short period of time, which is what the MMR vaccine effectively is. One recent report (Nov, 2004) that lends weight to this feeling is the UK's independent study into Gulf War Syndrome which found it to be an organic disease and pointed to multiple vaccinations given to troops, amongst other factors, as a possible trigger for the illness. Similar conclusions were also drawn by two US studies in 2004.
Although the media coverage of the MMR debate has died down, the debate is sure to rage behind closed doors for a long time to come as parents continue to see their child's health deteriorate following vaccinations.
Another possible cause of symptoms stemming from vaccinations is the inclusion of mercury preservatives in vaccines. Mercury in vaccines is discussed in the 'heavy metals' section below.
Following on from the previous paragraphs above about gut microflora disturbances, we'll now look at the possible role of yeast, specifically Candida, in ASDs. Dr. Shaw of The Great Plains Laboratory and formerly of the Centers for Disease Control and Prevention (CDC) has found that people suffering from ASDs (and other environmental illnesses) consistently have elevated levels of certain organic acids in their urine. He first noticed this in two autistic brothers who also had occasional muscle weakness and published his findings in the Journal Clinical Chemistry in 1995 (8).
Dr. Shaw was originally looking for metabolites characteristic of congenital errors of metabolism that are associated with muscle weakness. All of these metabolites showed normal levels, however, other more unusual substances were consistently elevated. One in particular, tartaric acid, stuck out. One autistic child had tartaric acid levels 600 times higher than the normal value. Dr. Shaw also found that when he looked at the medical records of his other autistic patients, they too had this abnormality. Dr. Shaw noted that this substance is primarily produced by yeast. The next logical step was to try a course of an anti-fungal agent to see if this improved symptoms. Dr. Shaw administered Nystatin, a common anti-fungal drug, to a 2 year old boy who was being evaluated for autism. The boy had developed normally up until 18 months of age but had then been given repeated courses of antibiotics (repeatedly shown to increase intestinal yeast levels) for an ear infection and had subsequently developed behavioral problems. After only a few days of Nystatin treatment the boys eye contact returned to normal and his tartaric acid level markedly decreased. It took 60 days for the tartaric acid level to return to normal however. Tartaric acid accounts for the muscle problems because it is a known muscle toxin. It is also similar to malic acid which is an important part of the Krebs Cycle which in humans accounts for most of the energy production from food. An important note with regards to tartaric acid being a muscle toxin is that high levels are also found in fibromyalgia patients.
Other complementary findings come from Dr. Sidhir Gupta, a clinical immunologist in California. Dr. Gupta has 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. Dr. Shaw believes that most of the tartaric acid is produced by yeast in the GI tract as Nystatin, which isn't absorbed into the body, has been successful in returning tartaric acid levels to normal. Other substances that Dr. Shaw finds to be raised in autistic children, and attributes to intestinal yeast, are citramalic acid and 3-oxoglutaric acid.
The debate over the role of intestinal yeast overgrowth in chronic illness has been going on for decades. The confusion is mainly 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. This situation has hampered research efforts and understanding for a long time now. 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 ASDs 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 (11).
It can only be hoped that agreement over a definitive laboratory test for intestinal yeast overgrowth will lead to research looking at the role it may play in chronic, poorly understood illnesses, such as autism.
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. Shockingly in 1999 the American Food and Drug Administration released a report stating that children who received thimerosal containing vaccinations at multiple visits may be exposed to more mercury than is recommended by federal guidelines. In fact, children may have been receiving 100 times the 0.1 micrograms per kilogram of daily exposure considered safe by most authorities worldwide. This report has, however, resulted in positive action being taken. Following the publication of the report, the Environmental Protection Agency (EPA) and Centers for Disease Control (CDC) recommended that thimerosal be removed from all vaccines given to children. Whether this move has reduced new cases of autism is still open for debate however. A study of 2 US government databases 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. On the other hand California public health officials examined state records for the period 1995-2007 and found that cases of autism continued to rise in the 6 years after thimerosal was removed from children's vaccines in 2001.
Mercury is a known neurotoxin and could be especially harmful to the developing brains of young children. A study conducted in 2005 by Burbacher et al and published in the journal Environmental Health Perspectives found that ethylmercury (the form found in thimerosal in vaccines) had a higher affinity for the brain than other forms i.e. much of the mercury from thimerosal-containing vaccines ends up in children's brains (20). Mercury also disrupts biochemistry and can result in dysfunction of multiple enzyme systems and damage to cell membranes and many proteins involved in all bodily functions. As can be said for the MMR vaccine, increases in vaccinations correlate well with increases in incidence of ASDs.
In a paper published in the journal Neurotoxicology by The Coalition for Safe Minds in 2001, the authors seek to determine the levels of mercury that could be expected upon hair analysis, based upon the amounts of mercury in vaccines routinely given to infants and children.(12). The paper predicts, based upon a proven model, that giving children all the usual vaccinations, 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 (17). 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.
Obviously children are exposed to mercury from other sources as well so their actual mercury levels could be expected to be even higher than this. The paper notes that:
"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."
A paper published in March 2006 in Environmental Health Perspectives would seem to shed more light on the mechanisms by which thimerosal can damage a childs health. Researchers at University of California, Davis, have found that in mice at least, thimerosal can disrupt the immune system. This large, well funded study for the university's MIND Institute and the National Institute of Environmental Health Sciences is sure to be an important indicator of where future research should be focused. 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. The research shows that these dendritic cells, especially the normal biochemical signals they process, 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.
Of course, mercury is not the only heavy metal that can cause health problems and vaccinations are not the only source of exposure to mercury. 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..
A number of researchers and institutions are now studying the possible role of exposure to chemicals in ASDs. A major study is underway at The UC Davis M.I.N.D. Institute, Schools of Medicine and Veterinary Medicine, and the College of Agricultural and Environmental Sciences funded by the National Institute of Environmental Health Sciences. Professor Isaac Pessah who is involved with this study states:
"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. The 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". They 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.
This is a large well funded study that should provide valuable evidence of any correlation between chemical exposures and ASDs. There is similar work going on in other locations around the world.
There have already been a significant number of studies published that have tried to determine the role that environmental chemicals play in the development of autism spectrum disorders. Dr's Edelson and Cantor of the Environmental and Preventive Health Center of Atlanta in the US suggest that "chronic exposure to toxic agents, i.e., xenobiotic agents, to a developing central nervous system may be the best model for defining the physiological and behavioral data found in these populations (children with ASDs)". In their own study of 18 autistic children the doctors carried out a range of tests to measure levels of toxic chemicals in the children's bodies and how well their livers were able to detoxify them. It was found that all of the children had liver detoxification profiles outside the normal range, indicating an increased toxic load on the liver. The results showed that 16 of the 18 children had levels of chemicals exceeding the maximum safe limit for adults. In the 2 children where high levels of chemicals weren't detected directly, they were found to have raised D-glucaric acid in their urine which is an indicator of a high level of toxins being metabolized by the liver. The paper goes on to discuss how these findings of toxicity could cause immune system disruption and lead to the behavioral symptoms associated with autism (13).
In a report published 2004, 'toxic contaminants' are linked to increases in the prevalence of attention deficit hyperactivity disorder, autism, and associated neurodevelopment al and behavioral problems in developed countries. The author also suggests that exposure of the foetus to chemicals while still in the womb could lead to development of these disorders. 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 (14).
Low Glutathione and Oxidative Stress
Glutathione is one of the bodies most important antioxidants, especially in cells important to the process of detoxification and elimination of environmental toxins, primarily in the liver. Researchers at the biochemical genetics laboratory at Arkansas Children's Hospital Research Institute have found that about 80% of children with autism have reduced levels of glutathione and its precursor nutrients such as the amino acids, cysteine and methionine (18). Reduced levels of glutathione would increase the level of oxidative stress. Oxidative stress occurs when antioxidants aren't able to clear the body of free radicals (highly reactive chemicals), which can damage cells in the brain, gastrointestinal tract and immune system. Professor Jill James, who headed the research states:
"[Our findings] suggest that these kids would be more sensitive to an environmental exposure and would be less likely to detox from heavy metals,"
This is a very interesting fact when placed in the context of children developing autism after being given vaccinations containing mercury compounds.
This is by no means the only study indicating that those with autism have decreased antioxidants and resulting increased oxidative stress. In a recent Turkish study of 27 autistic children and 30 healthy controls, findings such as increased Nitric Oxide (NO) in the autistic children were also indicative of increased oxidative stress (19).
Gluten and Casein
I'm sure everyone is familiar with the opiate drugs such as opium, morphine and heroin. It would be reasonable to ask what these very powerful and potentially damaging drugs have got to do with autism and children's health. All will be revealed shortly.
As you are probably aware, 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.
As we've already talked about, 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. 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 (15, 16). 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.
Learn more about the GFCF diet
Research has consistently made a connection between the increasing age of fathers and the incidence of autism. A major study published in 2008 which used data from the US Centers for Disease Control and Prevention's 'Autism and Developmental Disabilities Monitoring Network' found that the age of both mothers and fathers was linked to the risk of a child developing autism.
The research published in the American Journal of Epidemiology found that older parents, both mothers and fathers, are more likely to have a child with an autism spectrum disorder (ASD). The study results suggest that mothers aged 35 or older have a 30% greater chance of having an autistic child compared to mothers aged 25 to 29, while fathers older than 40 had a 40% higher risk than those aged 25 to 29. In addition, the study noted that firstborn children were the most likely to be affected by ASDs; firstborn offspring of 2 older parents being 3 times more likely to develop autism than third or later-born offspring of mothers aged 20 to 34 and fathers aged less than 4022.
Treatment of Autism
This is a huge and complex subject to tackle so we will not do so in any detail here. Conventional behavioral and speech therapies can be very beneficial so are of course to be recommended. Here at The Environmental Illness Resource we would also recommend the biomedical approaches, including dietary changes and nutritional supplements as advocated by the Defeat Autism Now! (DAN!) approach adopted by a growing number of doctors (alongside more traditional therapies). You can learn more about DAN! treatments here.