Public awareness of autism has risen considerably since the turn of the new millennium, largely resulting from increased media coverage, and a rapidly expanding body of scientific knowledge.
Parents and caregivers understandably have many concerns over what they read on the Internet, and hear in the media and from friends. Information on autism abounds, some of it true or partly true, some of it entirely false, and all of it very confusing.
And today, as currently diaried on the front page, autism made major headlines as the seven-year long U.S. Federal Court of Claims Omnibus Autism Proceeding issued its findings that concluded without reservation that vaccines and the vaccine preservative thimerosal do not cause autism. The Special Master, in fact, concluded that "the evidence was overwhelmingly contrary to the petitioners’ contentions".
Not everything is known about these complex, puzzling, and lifelong disorders – far from it. What is known, however widely unrealized by the public, is that autism is not a singular condition, just as a cold is not a singular condition.
Regrettably, there are as yet no certain biological markers of autism, no blood tests that can determine the presence of autism. And autism does not announce itself in the delivery room.
Instead, doctors diagnose autism using a set of behavioral indicators that have evolved over the six decades since the term "autism" was first used. Today, the term actually applies to three diagnostic groups of developmental disability, which doctors refer to as autism spectrum disorders (ASDs).
While such grouping implies that each represents a degree of severity of the same entity, there is actually no evidence for this. They could, and might very well, have unrelated causes. The idea that autism may not be a single disease but rather several has gathered support in recent years from evidence supplied by magnetic resonance imaging of the brains of autistic children.
Although the three forms of ASD – Asperger Syndrome, autistic disorder, and pervasive developmental disorder not otherwise specified (PDD-NOS) – certainly differ, they share three main features. Children with an ASD have impairments in social skills, and in communication, and they have restricted interests and repetitive behaviors.
The popular image of autism is strongly colored by an entity called Asperger Syndrome (AS). AS has become a common – perhaps too common – diagnosis assigned to young and often school-aged children who have difficulty relating to their peers.
Unlike classic autistic disorder, people with AS often have above average or even superior intellectual functioning. As children, they show no delays in the development of linguistic and cognitive abilities. People with AS may, in fact, have superior verbal fluency, and they often have strong, though unusually focused intellectual interests.
However, without exception they have impairments in social skills. They are not intuitively able to read other people’s feelings, or detect or respond to social cues. This often leads them to become labeled "odd", or "different" by their teachers, peers, or even their parents.
By contrast, children with autistic disorder don’t talk much; when they do, they often talk to themselves, or merely echo what they hear. To varying degrees they are withdrawn and inaccessible, seeming to regard people as unwelcome intruders. Eye contact is infrequent, and parents’ bids for attention are often ignored.
In regards to intelligence, children with autistic disorder vary from the gifted to the severely challenged. They often have an excellent memory, but they lack imagination, choosing to interpret what is said to them concretely.
Children with autistic disorder often play in a repetitive manner. They demand that their toys and clothes remain in the same place every day. They commonly do not cope well with transitions, or changes in routine. They are also very intolerant of strong sensory stimuli.
Finally, children with autistic disorder may become aggressive, self-injurious, or resort to self-stimulatory behaviors, which serve to calm them. As a result, these children’s socially inappropriate behaviors make it difficult for families to go out in public places.
Autistic spectrum disorders know no racial, geographic, or social boundaries. They occur 4 to 5 times more often in boys than girls, and more commonly among siblings of an affected child.
The CDC estimates that about 1 in 500 American children have autistic disorder, and that 1 in every 150 children meet diagnostic criteria for one of the autism spectrum disorders.
It is clear that more cases of autism in recent years are being recognized, but it is not clear whether more cases of autism are actually occurring. Most experts feel that autism has in fact not become more common, that there exists no real "epidemic" of autistic spectrum disorders.
Rather, they believe, the "rise" can be explained largely by that physicians are applying the diagnosis far more commonly and correctly than in the past.
Before 1980, there were no standard criteria for autism. Any diagnosis of autism was based on the definition of each individual physician. People now labeled autistic in the past might have been given some other diagnosis.
For example, a number of studies have revealed that children once labeled as "retarded" are now more likely to be given the more specific diagnosis of "autistic". Which is not to say that all, or even many, autistic children are cognitively delayed.
Growing evidence also suggests that a significant portion of the "rise" in autism can be explained by the gradual broadening of the definition of ASDs to include children with milder, more subtle symptoms. Children once described as "quirky" or "unusual" are today more likely to be diagnosed with an ASD. Heightened awareness of autism among parents and doctors has certainly aided this phenomenon.
Evidence is overwhelming that the cause of autism has a substantial genetic component. Researchers are discovering a growing number of genetic abnormalities that correlate with susceptibility to autism. Perhaps as many as ten or more genes or chromosomal abnormalities may relate to the various symptoms of autistic spectrum disorders.
Evidence clearly shows a high degree of heritability within families. While the overall chance of having a child with an autism spectrum disorder (ASD) currently stands at 0.6 percent, the chance of having a second child with an ASD lies between 15 and 20 percent.
Furthermore, twin studies demonstrate that is one non-identical twin has an ASD, the other will have it also about 10 percent of the time; for identical twins, the chance exceeds 90 percent.
However, the majority of autistic spectrum disorders occur in individuals without a family history of an ASD. Researchers therefore believe that some or many cases of autism are the result of new and spontaneous genetic mutations, but much more remains to be discovered about the genetic basis of autism.
But are there other causes of autism? This is where things get a bit tricky, especially when it comes to information read on the Internet, or heard on the morning talk shows or from friends and acquaintances.
It must be remembered that autism is not a singular thing. It is a spectrum – in other words, there are a wide range of symptoms or features of autism, and each of these features may range from mild to severe.
The diagnostic criteria for autism spectrum disorders cast such a wide net that many children with other primary medical conditions or diseases that have developmental consequences, or lead to developmental regression, will be labeled as "autistic", when in fact "autism" is not their primary disease, rather a consequence of their primary disease.
Confused? Even physicians get it a bit mixed up.
To put it a different way: some children early in childhood develop a disease, sometimes suddenly, that affects their development in such a way that it is slowed, stopped, or caused to regress. The resulting developmental disabilities can sometimes then fit into the criteria of an ASD, and the child is labeled "autistic".
While in a sense they are, nonetheless autism is not their underlying condition. Rather, the child has a sort of "secondary autism", if you will.
Conditions known to predispose children to developmental disabilities that meet diagnostic criteria for an ASD include , Fragile X Syndrome, Inborn Errors of Metabolism, Rett Syndrome, Tuberous Sclerosis, Prader-Willi Syndrome, severe lead poisoning, congenital rubella, some forms of epilepsy, and rare disorders of mitochondrial function.
What about vaccines? Do they cause autism? In a word, no. The notion that vaccines cause autism has been clearly and soundly disproved. Still, the issue is reported in the media and across the Internet as a controversy.
It is understandable why parents might think vaccines create autism. Autism symptoms are usually first noticed between the ages of 12 months and 3 years. Of course, these are about the same ages when children receive a number of vaccines, though most are received before the first birthday.
In addition, we give many more vaccines to infants and toddlers now than we did in the past, though the number of antigenic particles – germ particles stimulating an antibody response – is a tiny fraction of the number of even three decades ago.
In 2004, the Institutes of Medicine – a branch of the non-partisan and non-governmental National Academy of Sciences – released a report concluding that no evidence exist linking vaccines with the development of autism. Since 2004, the scientific evidence against such a link has become even more overwhelming.
But isn’t there mercury in vaccines? No longer. Even when there was, it was not the same "mercury" that we think of as that silver fluid in old-fashioned thermometers.
Instead, it was Thimerosal, a preservative used from the 1940s until 2001 as an additive to vaccines. It was very effective at preventing bacterial and fungal contamination, which was especially important for multi-dose vials entered and re-entered by medical professionals. Many routinely recommended childhood vaccines have never contained thimerosal, including the MMR (measles-mumps-rubella) vaccine.
Despite years of study around the globe, there has been found no evidence of a link between thimerosal in vaccines, and autistic spectrum disorders. Even still, as a precautionary measure thimerosal was removed in 2001 from all routinely recommended vaccines manufactured for administration to infants in the U.S.
The last batches of thimerosal-containing vaccines expired in January 2003.
Despite that thimerosal has disappeared, autism remains. Since 2003 the number of cases of children with autistic spectrum disorders has continued to rise. No better proof of the lack of a link between thimerosal and autism could indeed exist.
But what about the MMR vaccine? Here, again, is a "controversy" with no scientific merit.
More than a dozen subsequent studies from around the globe have consistently found no link between this vaccine, and autism spectrum disorders. Study upon study – from locales as diverse as the UK, Finland, California, Georgia, Denmark, and Japan – has confirmed that the rate of autism is the same in populations of children having received, and having not received, the MMR vaccine.
Despite solid, consistent, reproducible scientific evidence from around the globe against a link between vaccines and autism, many parents remain fearful of vaccines. This is more than just a shame – it’s a serious health risk to those children not vaccinated against germs, such as whooping cough, measles, and haemophilus, still in our everyday environment.
Even within my own practice, recent months have seen several cases of life-threatening vaccine-preventable disease. Please don’t let your child be the next case.