Causes of autism

Experts are unsure about the exact cause of autism but they have several theories as to what the likely causes are. One of these theories suggests that autism develops as a result of several causes, all of which are physical in nature. These physical causes then affect the development of the brain.

What they do know is that autism is not caused by upbringing, emotional trauma or some weakness on the part of the sufferer themselves. It is not a ’self-inflicted’ condition or caused by lifestyle factors.

Possible causes include:

  • Genetics
  • Vaccine
  • Differences in the brain
  • Immune system problem
  • Food allergies


There is evidence to show that families which contain an autism sufferer tend to pass this on to their children. Plus a family which already has an autistic child is at an increased risk of having another autistic child.

So, autism can run in families. But there are cases where a child does not inherit this tendency even though they have a member of their family with this disorder.

This means that there may not be a single ’autism gene’but instead, there is a combination of genetic differences which lead to this disorder. Plus there is the fact that autism is a ’spectrum disorder’which means that it affects people in different ways.

It all depends upon where that person fits on the autism spectrum. The type of autism they have will determine their symptoms, but, not every autism sufferer displays the same symptoms. For example, some people with autism experience mental health problems, hypersensitivity and insomnia, but others do not.

What does this mean in terms of genetics? What it means is that there could be different sets of genes for different types of autism.

To take this even further: there are people who develop autism due to a ’spontaneous mutation’rather than inheriting an autism gene. A spontaneous mutation is where a fault occurs in a cell which then affects DNA sequence and can lead to a genetic disorder.

More research is needed to determine the causes of a spontaneous mutation and how this is related to autism.


This refers to the intense media coverage surrounding the MMR vaccine. The MMR (measles/mumps/rubella) vaccine was designed to protect children against these common conditions which can lead to serious complications.

But there were reports stating that the vaccine was linked to an increase in cases of autism. However, evidence shows that there is no proof of a link between autism and the MMR vaccine.

Differences in the brain

There are differences in brain development between the autistic brain and the typical brain. The autistic brain seems to be bigger and hardwired differently so that it processes information differently.

Certain areas of the brain are larger, e.g. the amygdala, and behave in a different way to the typical brain. There is also a link between the male hormone testosterone and autism which might explain the higher numbers of boys with this disorder compared to girls.

The ’hardwiring’of the brain occurs in the early years of development when the brain is undergoing rapid changes. A particular area of the brain affected by these changes is the cerebral cortex.

The cerebral cortex is the part of the brain responsible for cognitive functions such as the memory, reasoning, movement and language. It is a complex and finely tuned area but if it develops too quickly then this disrupts many of these functions which then lead to autism.

The outcome of this is that autism affects the behavioural aspects of the brain to a great extent. This includes processing of information and problem solving. It is particularly noticeable in situations which require social interaction and communication.

This does not always affect intelligence so an autistic person can have a high IQ but is backwards in terms of social skills.

Immune system problem

This is research evidence which argues that autism may be caused by a fault with the immune system, e.g. an autoimmune disease. Plus there are autistic people who also have health problem caused by a compromised immune system.

But further evidence is needed.

Food allergies

There is a theory which suggests that allergies to certain foods which are wheat or dairy based may cause autism. But, there is an argument which states that a percentage of children with autism suffer from gastrointestinal problems which are caused by a wheat or dairy allergy.

So, if foods which are wheat or dairy based are removed from the child’s diet then there is likely to be an improvement in their physical condition and their symptoms.

Environmental factors

There is a suggestion that certain environmental factors can cause autism. These include solvents, chemicals used in the production of plastics, pesticides, diesel exhaust fumes, smoking and alcohol.

Proponents claim that they either cause autism or worsen the symptoms of autism.

It appears to be the case that environmental factors and genetics play a part but to what extent is still largely unknown.


The causes of autism are complex and further research is needed to validate or reject these theories.

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