Expert Q+A: Is There a Link Between Vaccines and Autism?

Q. I've heard autism is on the rise. Why?

The first question we have to ask is, do we really have an epidemic or are more children just being diagnosed? Is it better detection due to better awareness? Are we displacing one diagnosis for another? Here are some explanations for the large rise in autism:

  1. Displacing one diagnosis for another. In previous generations, many children were diagnosed with mental retardation, schizophrenia, or some other psychiatric disorder. Today, many of these same kids are diagnosed with severe autism.

    For example, in 1996, 1 in 63 kids were diagnosed with mental retardation (measured by an IQ score of under 70). Yet, in 2000, that number DROPPED to 1 in 83. Why? Were there suddenly much fewer kids with mental retardation? No, many of these kids are now diagnosed with autism instead of mental retardation.1 In other words, autistic kids were there in the 80's and 90's--we just didn't call them autistic.

    In 1991, the Individuals with Disabilities Education Act (IDEA) required children with developmental disabilities to receive school services and be integrated into a mainstream classroom setting as much as possible. Autism was added as a new diagnosis for which a child could be eligible to receive educational services. In 1993, two years after this code was added, the Department of Education reported a 23% rise in autism. Prior to the coding change, kids with autism were often labeled with non-specific developmental delay, brain dysfunction, or mental retardation.
  2. Changing criteria, broader diagnosis. The definition of autism has changed over the years. The Diagnostic and Statistical Manual of Mental Disorders (DSM) is the authoritative bible for psychiatric disorders in the U.S. The first two editions never even listed autism as a disorder.

    Dr Leo Kanner first diagnosed Autism in the 1940's. Yet it was not until 1980 when psychologists recognized autism. That's when the DSM for the first time listed criteria for diagnosis of autism.

    The autism diagnosis broadened again in 1994 when several more disorders were officially added to the DSM: Pervasive Developmental Disorder (PDD), PDD-NOS (not otherwise specified), Asperger's Syndrome, Childhood Disintegrative Disorder, and Rett's Disorder. By expanding the definition of autism, suddenly many more kids were declared autistic. Case in point: looking at recent autism diagnoses, up to 75% of these kids are high-functioning children with PDD-NOS or Asperger's.

    Unfortunately, many states don't break out where kids are on the autism spectrum. California's autism rate is often cited in the media as example of the "autism epidemic"--yet California doesn't break out where kids are on the autism spectrum, so it's hard to get solid numbers. Not long ago, kids who were smart but socially awkward had no diagnosis. Today, those kids are often diagnosed with Asperger Syndrome.2
  3. Better awareness, better and earlier diagnosis. Popular diagnoses rise and fall like skirt lengths. Think about it--ten years ago, had you ever heard of Restless Leg Syndrome? When it comes to autism, this newfound awareness is actually a positive step. More people-parents and doctors alike-are on the lookout for children with autism.

    Making a diagnosis and starting therapy earlier in life improves kids' longterm outcomes. But it also looks like autism is on the rise. Why? Because kids were previously diagnosed with autism after age five or six. Today, kids are diagnosed as early as 18 months of age. This adds many more kids to the rolls . . . but is autism really increasing? Or is there just an earlier diagnosis?
  4. Why does the U.S. have so many autism cases? Autism is not just an American disease -- it happens worldwide. But why do the U.S. and United Kingdom have such high autism rates? That's because the U.S. and U.K. have done the lion's share of research and studies into autism.

    Other countries are just starting to look into autism. For instance, in South Korea, kids are diagnosed with Reactive Attachment Disorder (RAD) ... which is really what we call Autism Spectrum Disorder (ASD) here in the U.S. We suspect that South Korea will report an alarming rise in autism when they figure out their RAD kids are the same as our ASD kids. And counting autistic kids is a relatively recent phenomenon. Before recent legislation led to schools labeling more kids as autistic, researchers just looked at either medical or school records to determine autism rates. This was imprecise to say the least.3
  5. Prevalence vs. Incidence. If you've ever taken a statistics class (or tried hard to forget anything you learned if you did), here is a little review. Most of what we know about autism rates are based on prevalence studies: these are a sampling of a population at one point in time used to estimate overall rates. By contrast, incidence studies identify the ACTUAL number of autism cases over a period of time. The only way to know if autism is really an epidemic is to see a rise in the incidence of autism. Unfortunately, there are very few incidence studies of autism. That's because it is extremely difficult to do this research. Only one incidence study on autism is available--that 2005 report found that rates of PDD in the 90's were unchanged. So even though PREVALANCE studies seem to show autism is increasing, the incidence proof is lacking.4
  6. Social acceptance. We've come a long way since autism was first identified as a disorder. Orignally, experts thought autism was caused by poor parenting--namely, the mother. These "Refrigerator Moms" were blamed for rejecting their kids, causing the kids to have social problems. Of course, this was WRONG.

    What we've learned over the past 70 years is that autism is not the mom's fault. But in the old days, no mother wanted their kid labeled autistic since that would imply HER guilt. Today, we realize it is not mom's fault--and thus parents are more willing to accept an ASD diagnosis. And the diagnosis now allows for special education services, which many parents realize can help their child.
  7. Over or misdiagnosis? There is so much awareness now of Autism Spectrum Disorders, that perhaps clinicians are overdiagnosing it. One reputable study suggests that kids who actually have anxiety disorders, obsessive compulsive disorders, and personality disorders may be misdiagnosed now with ASD.5

    These are possible explanations for the "autism epidemic"--but we don't have all the answers yet. The bottom line: in the 1980's, one in 10,000 kids were diagnosed with autism. Today, it's 1 in 88. The U.S. is not the only country seeing this trend. Australia, Canada, Denmark, Finland, Iceland, Japan, and Sweden also report a disconcerting rise.

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