Better Diagnosis and So-called Epidemics

by Kristina Chew, PhD on October 30th, 2007

These days it seems that more children have autism and that we hear a lot more about autism: Why?

When people try to account for the dramatic rise in the prevalence of autism in the past few years—in the 1960s, autism was considered a rare disorder that occurred in only about 3 in every 10,000 children; the prevalence rate for autism is now 1 in 150 among children in the United States (and 1 in 94 in New Jersey, where I live)—they often turn to external factors. In the 1960s, parents themselves, and mothers in particular, were blamed. During the time in which both awareness of autism and the numbers of children diagnosed with it increased greatly—even to the extent that some have proclaimed that there is an “epidemic of autism”—many factors have been tagged as “causes of autism,” from environmental pollution to the MMR vaccine, from TV to ultrasounds, to some that seem quite bizarre. Many counter the findings of research about the genetics of autism by pointing to “the environment” as setting off some “trigger” in a child with a “genetic predisposition” to autism.

But could it be that we are simply diagnosing autism better? That we ourselves have gained greater knowledge and understanding of autism, and are therefore counting cases of autism more and more accurately?

For autism is not the only disease whose rate has increased to the point that some speak of an “epidemic.” In today’s Washington Post, Roy Richard Grinker, a professor of anthropology at George Washington University, writes about how an increase in diagnoses of a disease does not necessarily signal an epidemic. Grinker is the author of Unstrange Minds: Remapping the World of Autism, in which he argued that better diagnosis—thanks to a combination of many factors, including more understanding of autism, changes in the criteria used to diagnose autism, and changes in society and culture about disability and difference—-is behind the rise in the autism rate. (See these two graphs.) In his Washington Post piece, Grinker looks at increases in the incidence of other diseases: Melanoma, which “dermatologists report a nearly 300 percent increase in…..over the last 20 years,” and prostate cancer, whose incidence “jumped 85 percent” between 1987 and 1992:

something dramatic happened in 1987: Doctors started to perform a simple blood test to screen for prostate specific antigen, or PSA, levels, a marker for prostate cancer. Almost overnight, more early-stage cases were detected and treated. What looked like an epidemic of prostate cancer was, in fact, major progress. Before that time, cases were detected only if a man received a transurethral resection of the prostate, or TURP; the procedure involved inserting a small telescope into the prostate through the penis and chipping away pieces of the prostate for analysis. Not surprisingly, doctors performed the procedure only when truly necessary.
Then, between 1992 and 1996, rates of prostate cancer dropped almost as precipitously as they had risen.

“This didn’t mean there was necessarily more disease during the rise or less disease during the decline,” says Thomas M. Pisansky, a professor of oncology at the Mayo Clinic College of Medicine. “Most researchers agree that the rise was due to the PSA, and the fall was due to getting all those men diagnosed.” It’s as if a fisherman suddenly found a better way to catch fish. At first, he’d have a high yield, but over time there would be fewer fish to catch.

In another example, Grinker notes that the prevalence of hypertension has risen over the last 10 years: While “fast food and a more sedentary lifestyle” are often pointed at as the culprits, hypertension has been redefined:

In 2003, an expert committee concluded that individuals with a diastolic pressure (the bottom number in a blood pressure reading) of 80 to 89 (then on the high end of “normal”) were at risk of developing hypertension-related disease and should be called “prehypertensive.” Physicians soon began to treat such patients for hypertension, and, for insurance and medical records, they were coded in the same way as someone with a much higher blood pressure. The number of diagnosed cases of hypertension thus rose.

Similarly, autism has gone from being a “narrowly defined disorder” to one that is “now used to describe a wide spectrum of severity.” The very methods that scientists use to count cases has also affected the rates of many diseases, as have the type of records that are now available to scientists to study:

For example, the Centers for Disease Control and Prevention recently searched medical and educational records and found that the proportion of children with autism in New Jersey was more than three times higher than in Alabama. The most likely explanation for this disparity is that Alabama lags behind New Jersey in providing medical and educational services for autism. Without services, many autistic people in Alabama could not be counted because there was simply no sign of them in the records the CDC analyzed.

Records for autism may become even more refined in light of the reports released yesterday by the American Academy of Pediatricians (AAP). The first report, “Identification and Evaluation of Children with Autism Spectrum Disorders,” calls for “universal screening” by pediatricians of all children at 18 and 24 months, regardless of whether or not there are any concerns about autism. Early diagnosis—even very early diagnosis—of autism is more and more likely, as understanding about what autism is increases. The report lists several screening tools (such as the CHAT (Checklist for Autism in Toddlers), the CARS (Childhood Autism Rating Scale), the AQ (Autism Quotient) ) that have been developed to identify symptoms and signs of autism. Yesterday also saw the launching of the Think differently about autism campaign by the UK’s National Autistic Society, “to raise awareness and understanding of autism by encouraging the public to see the world from the point of view of the people it affects” and also ” to spread the word that autism need not be so devastating and disabling if only people would take the time to understand it,” as Mike Stanton writes. Not only can we see autism, or signs of it, earlier in a child’s development; we are also learning how to truly see what autism is:

….autism is so much more visible—-autistic children and persons can be so much more visible—than they used to be: There is a lot more autism, just as there is a lot more awareness of autism.

In the wake of the Institute of Medicine’s April workshop on autism and the environment and the upcoming publication of the proceedings, it seems that more and more attention will be given to possible links between the rise in the autism rate and something in the environment. In 2007, $108 million in funding from the National Institute of Health (not, as noted in the article, from the National Institute of Mental Health) has been allocated to autism—up from $22 million in 1997. But, as Grinker points out, such investigations need to keep in mind other reasons—other changes in how our society looks at disease and disorder; at how it seeks to categorize it; at how it keeps track of it (through increasingly sophisticated software, as Grinker notes). We now have the tools, the techniques, and the diagnostic checklists to identify a lot more of the autism that is out there, and, even more, we are looking for it. Some change in our mindset—in how we understand perceive humanity, disease, difference, and culture is afoot, and our growing ability to see autism and to make the world “autism-friendly” are signs of this change. Writes Grinker in the Washington Post :

Despite all the tragedies we read about in the news, our world is actually safer than it has ever been. Yet we live in dread of epidemics and anxiously await the release of the latest figures from the country’s health-care leaders. Ironically, many of our fears are the result of the knowledge generated by the many real advances in medicine. So the next time you see statistics documenting the increase of a disease, take at least a moment to consider whether they may be evidence not of harm, but of good.

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