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Explanations For Autism

Updated on January 24, 2013

How Common is Autism?

Wing and Potter (2002) estimated that a given population would have between 8 and 30 people with autism per 10,000.

What is Autism?

Autism is a pervasive developmental disorder – it is a disorder that's unnoticeable at first but that slowly builds up (through the acquisition of symptoms) during a child’s development.

There are no physical symptoms with autism but there are several debilitating mental problems that come with it, mostly to do with having poor social skills.

What Symptoms Must you Show to be Diagnosed with Autism?

In something called the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) the necessary criteria that someone with autism must have are listed.

Symptoms must have been present since childhood and a total of six from the following listed symptoms must be present.

  1. Two symptoms must be present from the category of Qualitative Impairment in Reciprocal Social Interaction: failure to use eye gestures correctly (including eye contact), few personal relationships, disinclination for spontaneous sharing, a lack of empathy for others.
  2. One symptom must be present from the category of Qualitative Impairment in Verbal and Non-Verbal Communication: learning to speak later than average or being mute, echolalia, failure to initiate or sustain conversation, lack of imagination related play - when children imagine they are something or someone else and fantasise imaginatively.
  3. One symptom must be present from the category of Restricted Repertoire of Activities and Interests: repetitive movements, narrow interests (a lack of interest in a variety of subjects), needing to stick to strict rituals or routines.

Note: it should be noted that it may not be necessarily correct to state that autistic people have 'obsessions' or 'compulsions' as sufferers of OCD do. This is because we do not really know the feelings and thoughts of children with autism about their repetitive behaviours - this is due to a lack of research into this area and the difficulty of speaking to autistic children about their feelings (due to language difficulty and their lack of social interest).

The Majestic Wrinkly One

Understanding this mighty organ may be the key to our success in understanding autism.
Understanding this mighty organ may be the key to our success in understanding autism. | Source

The Neurological Explanation for Autism

The neurological explanation bases itself on the idea that there are abnormalities in the brains of autism sufferers which leads to their behaviours.

These abnormalities are usually found in the same areas of the brain of each patient and are always the parts of the brain that we associate with communication development and social functioning.

Post Mortem Studies' Contribution to Explaining Autism

Through examining dead bodies, we have found that autism sufferers have different structures for the following cortical areas:

  • The Limbic System - responsible for emotional regulation
  • Frontal Lobes - planning and control
  • Brain Stem & Cerebellum - motor coordination

Criticisms of the Contribution Post Mortem Studies have made to Explaining Autism

Cause & Effect - since post mortem studies have only ever been performed on adults we cannot know for sure whether or not autism is caused by these structural differences from childhood or whether autism causes these structural differences via its symptoms. For example, social hindrances may result in less use of socialising-specific areas of the brain and so improper or lessened development/degradation. Modern understanding of brain plasticity make this a very likely possibility. It is therefore very difficult to determine whether or not any of these structural abnormalities are the cause of autism.

The abnormalities seen through post mortem studies could have been solely or at least partly due to injuries suffered throughout the lives of the patients. Convincing theories of brain plasticity would suggest that this is not likely however.

An fMRI Image

An image from an fMRI scan which allows us to see changes in brain function (4 images per second!). The yellow parts show which parts of the brain an autistic person used whilst the blue shows the parts a regular person used.
An image from an fMRI scan which allows us to see changes in brain function (4 images per second!). The yellow parts show which parts of the brain an autistic person used whilst the blue shows the parts a regular person used. | Source

What Assumption Do Scans Make?

High blood flow to brain areas indicated an abnormality that lead to the associated impairment in qualitative behaviour.


A study by Piven et Al. (1995) found that autistic people actually have more brain volume than an unaffected person.

The Contribution of Neuro-Imaging to Explaining Autism

Neuro-imaging is the process of using technology to create images of the brain, often moving pictures, in order to identify the function of its different parts, or to look for abnormalities. All neuro-imaging techniques are non-invasive and so are relatively painless and convenient.

PET Scans
Positron Emission Tomography (PET) scans involves injecting a form of radioactive glucose into the patient and then using the PET sensor to watch which parts of the brain accumulate the radiation - allowing us to identify which parts of the brain are under/over functioning.

Zilbovicius et al. (2000)
Using PET scans, Zilbovicius reported a functional abnormality in the temporal cortex of 75% of the autistic children he examined. A mentally retarded control group showed no such abnormality providing great evidence for the idea that autistic children have a particular abnormality in a part of their brain.

SPECT (Single Photon Emission Computed Tomography) scans use less radiation than PET scans and so are more suited to scanning children’s brains.

Ohnishi et al (2000)
Used SPECT scans in order to find correlations between the following:

  • Blood flow in the frontal cortex and impairments in communication and social interaction.
  • Blood flow in the right hippocampus & amygdale and obsessive desire for sameness.

MRI and Its Use in Autism Research
Magnetic Resonance Imaging is the preferred method of scanning children because it does not use harmful radiation at all. MRI uses radio waves to cut magnetic fields in order to produce high quality 3D images of the brain and its structures.

Autistic children have been scanned and found to have abnormalities in their cerebellums – the part of the brain associated with attention. This explains the lack of attention span that many autism sufferers have.

Courschene et al. (1994) found that autistic patients had smaller vermal lobules in their cerebellums and other studies have shown that the cerebellum and brain stem are simply much smaller in autistic people.

It's DNA, Dummy!

Searching for genes in our DNA is a difficult but worthwhile task.
Searching for genes in our DNA is a difficult but worthwhile task. | Source

A Genetic Explanation For Autism

  • If one child has autism then there is a 3-6% chance that another child will have it, otherwise there is usually only a 0.6% chance of a child having the disease.
  • Autism is four times more likely to be present in boys, suggesting that genetics play a key role.
  • If one identical twin has autism there is a 90% chance that the other one will too (Folstein and Rutter [1977])

The Cognitive Theory's Contribution to Understanding Autism

The cognitive theory's ideas about autism base themselves around one central concept: that autistic children do not have a 'theory of mind'.

The theory of mind is the ability to imagine what other people are thinking or feeling even though you are not thinking or feeling the same things. What follows on from this then is the ability to be able to accurately predict what other people are going to do or think using knowledge of their mental state or their unique knowledge (they might not know something you do).

Baron Cohen et Al. (1985)

Three groups of participants were used:

  1. 20 autistic children (age: 6-16) [mean verbal age: 5.5 years]
  2. 14 children with down syndrome (age: 6-16) [mean verbal age: 3 years]
  3. 27 unaffected children (age and mean verbal age: 4.5 years)

The Experiment

  1. Two dolls were introduced to the children: Sally (with a basket) and Anne (with a box).
  2. Sally places a marble into her basket and then goes for a walk.
  3. In the meantime, Anne takes the marble from the basket and places it in her box.
  4. The child is then asked "where will Sally look for her marble?"

Results - % of Children who Couldn't Answer Correctly

  • 80% of autistic children
  • 14% of children with Down Syndrome
  • 15% of 'normal' children

Other Studies Supporting the "Lack of Theory of Mind" Theory

Perner et Al's Smarty Experiment (1989)
Presented autistic children with a smarty tube that turned out to contain a pencil. When asked what someone who hadn't already seen the pencil would say was in the box, the autistic children answered with 'pencil'.

Baron Cohen et Al's Comic Strip Experiment (1986)
Autistic children were presented with three different types of comic strip stories: mechanical, behavioural and mentalistic (requiring understanding of other people's states of minds).

The stories were in a messed up order and the task was to put them back into the correct order and explain what was going on.

The autistic children had no problems with ordering the mechanical and behavioural stories but could not manage the mentalistic one, failing to understand the mental states of the characters in the story.

What Do You Think?

Which is theory provides strongest evidence?

See results

Recap of the Main Symptoms of Autism

  • A lack of interest in social activities
  • A tendency to isolate yourself from other people
  • Failure to interact 'normally' as defined by society
  • Avoidance of eye contact and intimacy
  • Poor language skills, possibly echolalia (repeating a word(s) meaninglessly)
  • Particular repetitive behaviours like rocking or spinning an object
  • An overwhelming preference for routine and order and an outright disdain for changing already formed routines
  • Sometimes having a gift in a particular intelligence like art or music
  • Having a low IQ (below 70) - intellectual retardation


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    • Philanthropy2012 profile image

      DK 5 years ago from London

      Thank you very much.

    • phoenix2327 profile image

      Zulma Burgos-Dudgeon 5 years ago from United Kingdom

      Excellent hub on explaining this perplexing illness. Fascinating read.