Question from friend and wordpress guru marcelle:

“I’m curious about the current theories on what causes autism. I understand it occurs at a much higher rate than it used to (or that it is more frequently diagnosed), and I’ve heard the vaccination theory, and also heard that it’s bunk. So, I don’t really understand what’s going on here, or what is agreed upon (and disagreed upon) by informed scientists. I know that you don’t actually have the definitive answer to this — if you did, you’d be pretty famous — but I’m curious about the state of the discussion.”

Autism was first described as a disorder in 1943 by Leo Kanner, a psychiatrist out of Johns Hopkins.  In 1944, Hans Asperger in Austria described a similar condition, which became known as Asperger’s, and both of them are credited with identifying the symptoms associated with what we call autism spectrum disorders.  Of course, autism and other related disorders have been around long before 1943.  Martin Luther apparently described a boy with what was probably autism in his “Table Talk”, and his conclusion was that the boy was a soulless lump of flesh that was possessed by the devil.  People in Ireland and India described “wolf children”, kids left out in the woods by their parents and apparently raised by wolves.  The children were often mute, unable to walk or make eye contact, and insensitive to cold, and it is possible that some of these children could have been autistic (from “The History of Autism”, by Sula Wolff, 2004). 

So what IS autism?  From what I can tell, it appears that no one really knows.  ‘Autism’ and the ‘Austism Spectrum Disorders’ are really terms that are used to classify a certain group of symptoms.  People with autism may show all the classic symptoms, or none, and still be classified as autistic.

There are five main disorders that we call the autism spectrum disorders; Autistic Disorder, Rett Syndrome, Childhood Disintegrative Disorder, Asperger’s Disorder, and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS).  A comprehensive list of the main symptoms and what constitutes each can be found in the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition).  I’m not going to talk about Rett Syndrome or Child Disintegrative Disorder here, they are REALLY rare, and the question covers autism only anyway.  I am going to talk a little bit about Asperger’s, but mostly because I think it’s really cool, and because Asperger’s is one of the disorders that is aubject to a large growth in recent diagnoses.  PDD-NOS is lumped in with Autism for treatments and many epidemiological studies, so I’ll be covering it along with Autism as well.

Autism Defined

The DSM-IV defines Autism as having six of the following criteria:
1) Problems with nonverbal behaviors: this can include looking someone in the eye (one of the trademarks of classic Autism and Asberger’s), inability to control or use the proper facial expressions (smiling when you find out someone’s died, even though the person knows that is not the correct response), problems with body posture, and having problems with gestures that regulate social interactions (waving, smiling, reacting to the presence of others).
2) Problems developing relationships with people your own age.
3) NOT trying to interact with others.  People with autism often have trouble sharing interests with other people, do not show or bring or point out things to others.  There is some debate as to whether or not this is a characeristic of the disorder or a reaction to the behavior of others toward someone with autism.
4) No social or emotional reciprocity.  This means that if someone smiles at you, you don’t realize you should smile back and look at them, or if someone gives you something, you don’t realize that you should be grateful or give them something back, though of course it’s more general than that.
5) Problems with learning to speak, especially without using other attempts to communicate (such as mime or gestures, which might indicate hearing loss or physical speaking problems instead).
6) Problems initiating or sustaining a conversation with others.  They either do not know what to say, or cannot keep a flow of conversation going.  In response to someone saying “I like trucks!”, you might say “I like them too!”, while someone with autism may say “I have a cat.”
7) Stereotyped use of language.  Stereotyping (which in science has nothing to do with predjudice) means uncontrolled repetitive behavior.  So people with autism will repeat the same sound, word, or phrase over and over and over again.  They will also display echolalia, repeating anything that is said to them, without being able to respond in another manner. 
8) Failing to show spontaneous make-believe play.
9) Being preoccupied with a stereotyped pattern, with a strict adherence to routine or ritual.  So people with autism (especially children), will obsessively line things up, stack things, and use only the blue blocks.
10) Stereotyped motor mannerisms.  The most common one that you’ll see is hand flapping or waving, but there’s also head bobbing and whole body rocking, as well as whole body wiggles or tics. 
11) Preoccupation with PARTS of objects.  I’m not really sure exactly what this means, but I guess it would be just the wheels of a toy truck or something like that. 

Of course these symptoms are divided into several types, and you don’t have to have all of the symptoms.  But with all of these differences, it’s easy to see why you could have a room full of Autistic children, with every one showing a different set of symptoms. 

Asperger’s disorder is characterized by similar symptoms, only people with Asperger’s don’t have a delay or problem with language learning, no cognitive deficits, and may be well above average in intelligence.  These days a lot of people are saying that some famous people in the past (such as Ludwig Wittgenstein, the renowned logician) showed what could be characteristics of Asperger’s.  There’s also a really good book out about Asperger’s that I highly recommend.  Written by John Elder Robison, the book is called “Look me in the eye: my life with Asperger’s”.  I wouldn’t say it’s a really good book for understanding the clinical issues with Asperger’s, but it’s a fantastic memoir.


Usually all five disorders are lumped together under the heading “Autism Spectrum Disorder”.  Right now, it’s estimated that about 1 in 150 or 6.6 per  1,000 people are diagnosed with Autism Spectrum Disorder (Wolff, 2004).  It’s found in far more boys than girls, the ratio is about 4:1.  Many people have wondered whether or not numbers have been going up in the last century or so.  But keep in mind that autism as a diagnosis is only about 60 years old, so of course diagnoses have been going up. 

Also, until recently a lot of people with autism spectrum disorders have been passed over.  They are especially likely to get passed over if they have very high functioning Autism or Asperger’s.  There’s been a recent increase in diagnoses partially because, as one child gets diagnosed with severe symptoms, one or more family members are subsequently diagnosed with milder symptoms, it just took a major diagnosis to bring their disorder to light. 

Finally, Asperger’s only became a diagnosis in the early 1980’s, and no one really knew about it until the 90’s or so, when the disorder began to gain acceptance, and when more doctors learned to recognize the symptoms.  Prior to that, only severely affected kids were classified as anything at all, and then it was usually with autism.  Other kids were just known as “mentally retarded”, or just ostracized in school as “that funny kid”.  But now we have a name for the disorders that many of those children have, and so numbers of people identified as having Asperger’s or other autism spectrum disorders have of course gone up.

So What Causes Autism?

There are lots of theories out there about what causes autism, but the reality is that right now, there is no one cause.  Remember that “autism” is just a term used to describe a set of symptoms, but a set of symptoms is not a disease or disorder by itself.  So I’m listing below the main things that people have thought caused autism, from the funkiest to the most likely:

1) Refrigerator mothers:  This was a concept of psychiatry, who thought that autism was a psychosis (like schizophrenia) rather than a developmental disorder (though now we know that schizophrenia has a very strong genetic component, as well).  The idea was that, if your parents didn’t care about you and didn’t care for you properly, the result was that you grew up being completely unable to form relationships yourself. 

This is, of course entirely untrue.  However, some of the parents of people with autism sometimes have very unusual features, and may in fact have difficulty forming relationships themselves.  This is mostly due to the possibly genetic changes that may result in autism, and some parents of children with autism have been retroactively diagnosed as having high-functioning autism or Asperger’s.
2) Epilepsy:  Autism spectrum disorders are often present along with other disorders.  The most common ones are genetic disorders,  gastrointestinal problems, and epilepsy.  Epilepsy, or seizures, can cause further degeneration of the brain if they are particularly strong.  Right now, though, it appears that epilepsy is mostly something that is present along WITH autism, rather than causing it.
3) Pesticides and Pollution:  There is a theory that families living in areas with high pollution and pesticides may be more prone to having children with autism.  The major study was done out in California , where researchers found a correlation between maternal residence near areas of high pesticide use and incidence of autism.  However, there are lots of autistic children out there who haven’t been exposed to pesticides, and even in the study, you would have to live within 500 meters of a high pesticide area, during the first 1-8 weeks of gestation.  So as a general theory its relatively unlikely.
4) Vaccines: The idea of a vaccine causing autism started in the UK, with the MMR (measles, mumps, and rubella) vaccine as well as the TCV (thimerosal-containing, which is a preservative for vaccines).  Parents would get their kids vaccinated, and then a few of them would begin to notice symptoms of autism.  However, there is NO evidence that vaccines cause autism (DeStefano, 2007, Bishop, 2008).  Autism is a developmental disease, which means that the patterns and some of the symptoms are already present at birth, so administering a vaccine is very unlikely to start up a developmental disorder.  The reason people thought vaccines caused autism was because of the age at which they were given.  Kids get the MMR at about the 18 month doctor’s visit. Symtoms of autism are almost always first identified between 18 and 48 months.  Just in case, doctors did look at a lot of children and a lot of vaccines, as well as conducting some clinical trials, and they found no correlations between vaccines and autism.   (Steve Novella does a lovely job of covering this over at “sciencebasedmedicine“.)
5) Genetics: This one appears to be the strongest argument so far.  But which genes?  We don’t really know.  Many people think that, because far more boys get autism spectrum disorder than girls, it may be a sex-linked genetic mutation.  Of course, many other mutations are possible, and mutations have been seen in the dopamine and serotonin systems, as well as in sex-linked genes, and many many others.  Genetics so far really is the best explanations for the symtoms seen in the autism spectrum disorders (it’s a pity that none of our presidential candidates are willing to accept this, instead listening and giving credence to a small but very vocal minority without any science to back them up, Orac at Respectful Insolence has a well-done take on it).


There is no cure for autism spectrum disorders.  Many people with the disorder, as well as their caretakers and family members, see autism and the related disorders as just another way of being.  And for those with high functioning autism and Asperger’s, it doesn’t have to curtail their lives.  Many people with autism spectrum disorders have amazing talents (like the guy in “Look me in the eye”, as well as John Nash, prior to schizophrenia), and many get along just fine.  But of course, for those that cannot take care of themselves, there are some things that doctors and therapists can do.

Behavioral therapy is a must with autism spectrum disorders.  It can help a lot with delayed mental development and with developing languages, and it helps even more with teaching people the intricacies of human social interaction.  With the most severe forms of autism, occupational therapy is necessary to give autistic people as much independence as possible.  With the higher functioning forms, therapy can help kids join regular classrooms and succeed in school.

The drugs.  Right now, drugs are usually only prescribed to people with severe autism, especially those with severe agitation and a lot of repetitive movements.  Anti-psychotics can help a lot with agitation and repetitive or obsessive behavior, as well as stimulants suchs as methylphenidate (Ritalin) which is prescribed for ADHD.  Other than that, many treatments have been tried, and so far nothing else has been successful. 

So as a final answer to marcelle’s question and a take-home message: Autism Spectrum Disorders are genetic in origin, and the recent increase in diagnoses is primarily the result of better diagnostic techniques and wider definitions of what constitutes a disorder (such as Asperger’s).  The increase in diagnoses can be fully accounted for by improvements in diagnostic techniques and an increase in awareness. 

6 Responses

  1. I used to babysit for a 4-year-old with autism. His doctors had suggested a gluten-free and dairy-free diet, and his mother said it had helped his symptoms immensely.

  2. Did it help the behavioral symptoms, or other symptoms? A lot of children with autism have comorbid gastrointestinal problems, which could also have a big impact on irritability, aggression, or discontent that could not necessarily be communicated. So it’s possible that the diet helped a lot with GI discomfort and thus with behavior. Of course you couldn’t rule out other effects on behavior like the lower carbs and sugar in a gluten-free diet.

    On the other hand, mental retardation conditions like PKU can be induced by exposure to dietary components, so I suppose in the general rash of gene problems diet could play a role.

  3. You may find the recent TMS posts on my blog interesting with respect to autism. Dr. Alvaro Pascual-Leone and his team are making some significant new discoveries about our autistic minds and how they may be helped to reshape themselves.

  4. Mr. Robison, thank you so much for your comment! It’s an honor to hear from you, I loved your book! I will definitely be checking out the blog, my department has already had a couple of interesting discussions on TMS and its possibilities. Thanks so much for reading my humble little blog. 🙂

  5. Good job here.

  6. I have been very interested in Autism for the past two years since working with a child with autism. Many papers are released every day with new findings claiming to show how autism comes about. Some propose biological factors which seem to definately play a role since one in four children with autism also show to have epilepsy. Unfortunatly there has been no specific biological marker defined to explain the etiology. It has also been argued that enviromental and behavioural factors can explain the cause of autism. It seems that it is a debate of nurture vs nature. This is were I think the debate lies just now. Recently, John Morton has published a book looking at using the causal modelling approach integrating all of these factors. Its worth a read as it looks a hopeful approach for many developmental disorders

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