How often does Autism Occur: The Facts

In an article written for the Association of Parents of People with Autism, which took place in Madrid on May 5th, 2005, Dr. Eric Fombonne undertook an exhaustive review of the epidemiology of Autism Spectrum Disorder (ASD).   Overall Fombonne used 36 studies published between 1966 and 2003 involving 14 countries and a sample size of 7,514 children diagnosed with an ASD to conduct his analysis.

The following is a list of findings based on empirical evidence from the analysis of the 7,514 children diagnosed with an ASD:

    Intellectual Functioning

    29.6% of children were found to have no intellectual impairment

    70.4% of children were found to have some form of intellectual impairment; of these
    
    Of these children;

            29.3% were found to have mild to moderate intellectual impairment
            38.5% were found to have moderate to severe intellectual impairment

Gender Differences

    4.3 males for every 1 female

    Looking at the children with Autism and no intellectual impairment, the gender differences were more pronounced; 5.5 males for every     1 female.

    In the group of children with Autism that had moderate to severe intellectual impairments the gender ratio was 1.95 males for every 1     female.   This supports the statement that female’s diagnosed with Autism are much more likely to experience moderate to severe     intellectual impairments.  

Prevalence Rates

    Autism

    13 children for every 10,000 children born

    Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS)

    20.8 children for every 10,000 children born

    Asperger Syndrome

    2.6 children for every 10,000 children born

    Childhood Disintegrative Disorder

    1.9 children for every 100,000 children born

    Overall, Fombonne states that the best estimate for the prevalence of PDDs currently available is 60 children for every 10,000 children     born.  This translates to 1 child out of 167 (0.6%) children born being diagnosed with a Pervasive Developmental Disorder.      Interestingly, Rett’s disorder, one of the 5 PDD diagnoses included in the Diagnostic and Statistical Manual, was not included in these     estimates.  

Social Class
    
    There is no apparent correlation of the occurrence of autism within specific social classes.   Autism doesn’t discriminate.

Conclusion

In the arena of Autism, it’s critical that empirical evidence, rational thinking and skepticism rule the day.  Armed with scientific evidence, parents, professionals and interested parties can make good, informed decisions for the children with autism they are concerned with.  This Fombonne article reviews empirical scientific evidence to provide us with some good information about some of the many dimensions of the diagnosis of Autism and Pervasive Developmental Disorders.  

References

Perez, J.M., Gonzalez, P.M., Comi, M.L., Nieto, C. (2007). New developments in autism:    The future is today. Great Britain, Athanaeum Press.