The Rising Prevalence of Autism

Over the years, the definitions of autism have changed dramatically and this has resulted in equally dramatic changes in its prevalence. Starting with Kanner’s narrow view of what constituted autism, the definition of autism has been progressively widened in its scope.

From the mid-1960s onwards, child psychologists started using the word ‘autism’ to describe the exact opposite of what it had meant previously. In the 1950s, autism was used to refer to children who suffered from hallucinations and lived their day-to-day lives in a fantasy world. By the 1970s, the term autism was being used to describe children who completely lacked an unconscious, symbolic life and in fact did not fantasize at all.


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In 1972, Michael Rutter, a leading child-psychiatric researcher from the UK’s Maudsley Hospital who conducted the first-ever genetic study of autism, stated that, “the autistic child has a deficiency of fantasy rather than an excess”. The meaning of the word autism was then radically reformulated from a description of someone who fantasized excessively to one who did not fantasize at all.


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Definitions continued to be refined and broadened through the International Classification of Diseases (current version ICD-10) published by the World Health Organization and the Diagnostic and Statistical Manual of Mental Disorders (current version DSM-5) from the American Psychiatric Association.

As the definition evolved, autism came to include not only children with severe delays in language and cognitive skills, but also those with less severe forms such as Asperger’s and “high-functioning” autism.

As the definition of autism was widened, prevalence in the general population started to grow rather rapidly. Suddenly it seemed as if there was an epidemic, but it wasn’t really a change in the prevalence of autism, rather it was that autism was simply being recognized and diagnosed more effectively.

For example, investigations conducted in European countries prior to 1999 showed a median prevalence of .1%, in surveys competed in the 2000s this number had almost doubled to .185%, and by the 2010s data was showing a prevalence of .69%. However, these European studies are considered to underestimate the prevalence of autism as a result of varying methodologies and diagnostic criteria.


Dr. Abdul Momen2 sizedHis Excellency, Dr. Abdul Momen speaking at the United Nations on World Autism Day, April 2, 2013, in New York had this to say about prevalence:

Autism is the fastest growing serious developmental disability and since 2002 its growth rate is around 57%. As per the World Health Organization, approximately 1% of the world’s population or 70 million are affected by autism. Autism costs over $137 billion per year and this cost is expected to increase significantly. Recent findings, however, view that early diagnosis and intervention can improve outcomes.”


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A 2014 study by the Centers for Disease Control (CDC) in the US shows the rate of autism be as 1.67% (1 in 68). Boys were found to be more at risk than girls – with the rate being as high as 1 in 45. A more recent US government survey of parents shows that the total number of children diagnosed with autism could be as high as 1 in 45 or just over 2%.

As we have seen, the apparent rising tide of children diagnosed with autism can be mostly attributed to a widening definition of the condition combined with earlier and more effective recognition and intervention. There is no definitive test for autism. It can be diagnosed only by closely observing the behavior of affected child.

You can read more about the CDC study here on their website.