If There's No Autism Epidemic, Where are all the Adults with Autism?

In February, 2007, the Centers for Disease Control (CDC) announced the results of two surveys of autism spectrum disorders covering 22 states. Using the newly funded Autism and Developmental Disabilities Monitoring Network (ADDM), CDC researchers found an average rate of 1 in 150 children with an autism spectrum disorder, with New Jersey at the top, with a rate of approximately 1 in 100. On the surface, these figures suggest an epidemic.

When scientists respond that there has been no true rise in autism, that we are diagnosing autism more, and counting it better, believers in an autism epidemic— mostly parent advocates, philanthropists, and politicians—argue triumphantly that if there is no epidemic, then 1 of every 150 adults in the United States must, in fact, have autism. Along with journalists, they repeatedly ask, "Show me where the one in 150 autistic adults are. We can't find them."

Just where might those 1 in 150 adults with autism be?

As surprising as it may seem, they are living and working among us.

Some live at home with their aging parents or siblings. Some live in group homes, or in institutions. Some have jobs and live independently. Many have the diagnoses given to them when they were children, such as mental retardation, seizure disorder, or schizophrenia. Recently, one of us met a severely autistic 60 year old woman in eastern Tennessee , who we'll call Donna. Donna's internist diagnosed her with autism ten years ago, when she was 50. Her mother said that Donna's first label, in 1950, was "mentally retarded with emotional block and obsessive compulsive traits." Today, for the purposes of public assistance, she is classified as mentally retarded.

There is no record anywhere to suggest that Donna is "autistic."

Now, imagine another, more mildly autistic adult, who has a job with minimal social demands (filing medical records, perhaps), has poor eye contact, and some anxiety. Perhaps he is even married. After all, as they get older, many people with autism, like the well-known writer, Temple Grandin , make significant advances. First, he may not seek treatment or even think he has problems. Second, even if he did, he may not go to a psychiatrist, but rather to an internist who could treat his anxiety. Third, even if he did go to a psychiatrist, it is not likely the psychiatrist would diagnose an adult with autism, especially if the psychiatrist had no clinical data on his early childhood (autism is still a developmental disorder diagnosed in childhood, and the tools for diagnosing autism in adults are not nearly as valid or reliable as those for children).

So, unless such mildly autistic adults had been diagnosed as children, and unless there were good baseline data on these people as children, we would have a hard time going back in time and trying to predict whether they would have qualified for an autism diagnosis. Even in the old days when we had rates for autism of 5 in 10,000 children, epidemiologists would have been hard pressed to find the corresponding adults, unless they knocked on people's doors looking for autism. And even then, most of these people would not consider themselves to be "autistic."

As an analogy, consider Fetal Alcohol Syndrome (FAS), which occurs in about 1 in 500 children. Because FAS only became a diagnosis after the mid-1970s, there are virtually no adults with this diagnosis over the age of 30. (And yet no one would suggest that pregnant women only started to drink alcohol in the 1970s). To locate an adult with FAS you would have to have evidence of fetal alcohol exposure, plus childhood onset of the symptoms of FAS.

Another example would be speech and language disorders, very common in the general population, any easily countable among children.  It would be nearly impossible to ascertain the prevalence of speech and language disorders among adults, as many adapt to their problems (a lisp, a stutter), do not seek therapy, and do not carry a diagnosis of speech and language disorder into adulthood.

Recently, a senior epidemiologist at the Centers for Disease Control told us that she is unaware of anyone conducting a prevalence study of autism in adults, and that this is understandable given how difficult it would be to carry out. Last year, the CDC issued a call for proposals to conduct such a study but they received only one submission that, unfortunately, was too weak to warrant funding. We will likely continue to hear some journalists and some autism advocates say "We can't find autistic adults." But the reality is that they are not looking. And for good reason.

Children with autism are, of course, much easier to count than adults, because they are in schools, but they were once as invisible as many autistic adults are today. Indeed, Thomas Insel, the Director of the National Institutes of Mental Health , told Newsweek in November 2006 that during his psychiatric training in the 1970s he saw "not one child with autism." It's not just because he wasn't looking, or because Insel was not trained in child psychiatry. It's because they were misdiagnosed, institutionalized, and treated by neurologists (if at all). In the 1970s, psychiatrists seldom saw children and there were only a few hundred child psychiatrists in the entire country. One of our spouses, who did her residency at Massachusetts General Hospital in the 1980s, never saw a case of autism because the hospital had no developmental program at that time.

By the 1990s, child psychiatry had blossomed. Membership in the American Academy of Child and Adolescent Psychiatry had increased from several hundred in the 1970s to several thousand physicians. And in 1992, public schools had begun to use autism as a classification for children who received special services. Autism awareness soared. Today, there are better diagnostic tools, and therefore better records that scientists can use to estimate prevalence. The CDC's recently announced results are yet another example of how changes in our understanding of childhood developmental disorders have helped us count autism cases more accurately.

But just because we cannot count adults with autism does not mean that they do not exist; nor does it mean that the prevalence rate for autism in adults must be lower than it is in children. Adults with autism are, in fact, becoming increasingly visible as autism awareness continues to rise and as more and more adults begin to identify themselves as autistic, and speak and write about their experiences of growing up and living with autism. Their invisibility is not a sign that autism is a childhood epidemic, but rather of how different our knowledge of autism is today.

So it isn't surprising when Donna's mother, now eighty-two, looks at parents like us with envy. "I wish my child had been born today," she said. "She would get a proper diagnosis, have different therapies we could try, and we wouldn't be so isolated as a family."

We hope Donna's mother is right, that we really are in a better place today, and that when our children become adults they will not be invisible.

Roy Richard Grinker is Professor of Anthropology and the Human Sciences at The George Washington University and the author of Unstrange Minds: Remapping the World of Autism, which was recently published by Basic Books. Kristina Chew is Assistant Professor of Classics at Saint Peter's College and writes the weblog Autism Vox. Both are parents of children with autism.

©2006 Roy Richard Grinker