Is the Prevalence of Autism Increasing? 2

DSMIs the Prevalence of Autism Increasing?

With the recent release of the current prevalence rate of autism spectrum disorders (ASDs), people all over the world are asking, “Is the prevalence of autism increasing?”  Well, we don’t know.  There are a lot of factors at play including diagnostic criteria and reliability of diagnostic decisions.

First Description of Autism

The word autism describes an isolated self.  Today, the word autism is more commonly known as the developmental disability affecting approximately 1 in 68 children.  Autism was first described in 1943 by Leo Kanner, a psychiatrist and physician who spent the bulk of his career at The John Hopkins Hospital in Baltimore, Maryland.  After seeing multiple children who were otherwise thought of as atypical and demonstrated characteristics of schizophrenia, he noticed that these children were unique from what they psychiatric world had been exposed to.  Kanner knew these children merited further attention and began studying them.

Kanner outlined 11 unique cases of children that did not quite fit other diagnostic criteria at the time.  Case 1 in Kanner’s report is believed to be the first individual diagnosed with autism, Donald Gray Triplett of Forest, Mississippi.  Kanner identified similar characteristics and behaviors in studying Donald and the 10 other cases.  Each child exhibited isolation from social interaction (i.e., autism), obsessive behaviors (e.g., repetitive verbal and motor behavior), stereotypy (e.g., spinning objects, engaging in rhythmic movements), absence of spontaneous sentence formation, and presence of echolalia (Kanner, 1943).  The similarities noted among the 11 children he studied make up the criteria currently used for diagnosing autism spectrum disorder as identified in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5).  If autism was first described in 1943 and the DSM-5 was published in 2013, how did we define and diagnose autism in the 60 years after Kanner first shared his research with the world?

Early Definitions in the Diagnostic and Statistical Manuals

The first and second edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-I; DSM-II) were published in 1952 and 1968 respectively.  During that time, autism was classified under childhood schizophrenia with diagnostic criteria including social isolation (i.e., autism), atypical behavior, and withdrawn behavior (American Psychiatric Association, 1952; American Psychiatric Association, 1968).  The estimated prevalence of autism was approximately 5 in 10,000 in the 1960s (Newschaffer et al., 2006) and 1 in 5,000 in 1975 (Autism Speaks, 2009).  With such broad diagnostic criteria, it’s likely that individuals that meet the current diagnostic criteria for autism would have been diagnosed with intellectual disability (formerly mental retardation) or another disability outlined in the DSM-I and DSM-II.  What was the true prevalence rate of autism in the 1950s, 1960s, and 1970s?  We don’t know.

Later Definitions in the Diagnostic and Statistical Manuals

In 1980, the DSM-III was published including infantile autism as a separate category of diagnosis as well as childhood onset pervasive developmental disorder (PDD) (American Psychiatric Association, 1980).  Infantile autism was diagnosed based on a child demonstrating six characteristics including: 1) onset before 30 months of age, 2) pervasive lack of responsiveness to other people (i.e., autism), 3) gross deficits in language development, 4) peculiar speech if vocal (e.g., echolalia, metaphorical language, pronominal reversal), 5) bizarre responses to various aspects of the environment (e.g., resistance to change, peculiar interest in or attachment to animate or inanimate objects), and 6) absence of delusions, hallucinations, loosening of associations, and incoherence as in Schizophrenia (American Psychiatric Association, 1980).  These diagnostic criteria are much more objective and encompassing than previous criteria in the DSM-I and DSM-II.  In 1985, the estimated prevalence of autism was 1 in 2500.

Revisions were made to the DSM-III in 1987 resulting in the newly published DSM-III-R.  In the revised edition, autistic disorder was defined as a new diagnostic category as was pervasive developmental disorder, not otherwise specified (PPD-NOS).  Autistic disorder was diagnosed based on onset of characteristics during infancy or early childhood and demonstration of at least 8 of 16 characteristics within three distinct categories including impairment in reciprocal social interaction, impairment in verbal and nonverbal communication and in imaginative activity, and restricted repertoire of activities and interests.  PDD-NOS served as a catchall for children that did not meet the criteria for autistic disorder.

The biggest changes were made in 1994 with publishing the DSM-IV.  The DSM-IV included four additional categories of pervasive developmental disorders (PDDs) falling under the umbrella of autism spectrum disorders (ASDs).  In addition to autistic disorder, the DSM-IV outlined diagnostic criteria for pervasive developmental disorder, not otherwise specified (PDD-NOS), Asperger’s disorder, Rett’s disorder, and childhood disintegrative disorder (CDD) (American Psychiatric Association, 1994).  In 1995, the estimated prevalence of autism (including all disorders on the spectrum) was 1 in 500.

Current Definitions in the Diagnostic and Statistical Manual

Prevalence rates for ASDs in 2000, 2004, 2006, 2008, 2010 were 1 in 150, 1 in 125, 1 in 110, 1 in 88, and 1 in 68 respectively (Center for Disease Control and Prevention, 2014).  After much consideration to the diagnostic criteria for ASDs, the DSM-5 was published in 2013.  The DSM-5 combined the five uniquely defined ASDs into one diagnostic category, autism spectrum disorder.  This change was made in part to support high reliability in diagnosing with the ability to identify severity levels for ASD for each child.  Severity levels of ASD are outlined by the level of support required for an individual based on their symptoms related to social communication and restricted, repetitive behaviors.  The severity levels include: 1) requiring support, 2) requiring substantial support, and 3) requiring very substantial support.  Yes, the current prevalence rate of autism being 1 in 68 is staggering compared to the estimated prevalence of 5 in 10,000 in the 1960s.  However, over the last six decades, our diagnostic criteria have continuously changed and our society (including doctors and families) has become more aware of autism and its characteristics.

What Does It All Mean?

What are the implications of the current prevalence rate of autism?

  1. Our society, worldwide, needs an abundance of well-trained, highly-qualified service providers to educate individuals with autism and to train and support family members and other caregivers.  How comprehensive is the training received by our special educators, administrators, general educators, physical therapists (PTs), occupational therapists (OTs), speech-language pathologists (SLPs), behavior analysts (BCBAs), pediatricians, and other providers that routinely interact with individuals with disabilities?  What type of training and experience should we expect of our early childhood intervention (ECI) providers?  How much training and experience should we expect of service providers?  How do we get well-trained, highly-qualified service providers into the positions where they are actively serving families and children who need high-quality support and services?  These are a few questions I mull over from time-to-time.
  2. As a society, we need to educate ourselves on the indicators of autism and other developmental delays.  We should familiarize ourselves with developmental milestones and increase awareness of typical development in the areas of social skills, language and communication skills, cognitive skills, and motor skills.  Educating ourselves and adhering to the recommended schedule of well-child doctor visits will support early, routine evaluation of the development of our children.  The sooner we identify that a child is developing differently, the sooner we can supplement their daily routine with supports and services to close the gap between their development and typical development.

What do you think?  What are the implications of the current prevalence rate of autism?  Share your thoughts in the comment section below.

2 thoughts on “Is the Prevalence of Autism Increasing?

  • Danette Hardin

    The history and the statistics are well documented here and very much appreciated. Thank you

  • Georgiana Rennie

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    such information much. I was looking for this particular information for a very long time.
    Thank you and best of luck.

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