Definitions: Prevalence & Epidemic
The Autism Numbers: Why there’s no autism epidemic was the title of Arthur Allen’s review yesterday of Unstrange Minds: Remapping the World of Autism by George Washington University anthropologist Roy Richard Grinker. Allen noted that “thirty years ago, autism was thought to occur in one in 2,000 children; prevalence rates put it at about one in 200.”
To repeat some phrases: “There’s no autism epidemic.” “[P]revalence rates put [autism] at about one in 200.”
I wish to highlight here that “prevalence” and “epidemic” have two quite different meanings.
- Prevalence. “The total number of cases of a disease in a given population at a specific time.”
From the American Heritage Dictionary - Epidemic. “An outbreak of a disease or illness that spreads rapidly among individuals in an area or population at the same time.”
From the American Heritage Science Dictionary
Confusion of these two words is one reason that claims of an “epidemic of autism” are made: To say that there is “no autism epidemic” is not to say that there is a low prevalence of autism. The prevalence rate of autism is at its highest ever—1 in 166 (see the CDC’s data on ASD Prevalence Questions); the prevalence rate is not the same thing as the actual number of persons diagnosed.
Saying that there is no “epidemic of autism” is not a denial of how many autistic persons there may actually be.
In response to last week’s Time magazine article on whether or not there is an autism epidemic, I heard one parent comment that they did not know a single person with Asperger’s. I do not know much about this parent’s life (aside from the fact that we both have autistic children); I have to say that, with each passing day I spend in Autismland, I recognize that this or or that person I knew in the past and had this or that “different” interaction with may well have Asperger’s syndrome, whether diagnosed or not.
What if autism is under-diagnosed?
Addendum @ 16.39: A recent comment on What if there is no autism epidemic? adds some thoughtful points: “I believe that the number of children who are profoundly disabled, moderately affected, and just atypical in ways we now call the autistic spectrum may not be significantly different than in the past. Maybe more children are affected; the old database isn’t as reliable as recent data.” Go here to read the entire comment.
6 opinions for Definitions: Prevalence & Epidemic
Julia
Jan 16, 2007 at 6:48 pm
There are probably parents who would say that, but who don’t KNOW they know someone with Asperger’s Syndrome.
I confine my actions somewhat when I’m with one particular group. Most of them may not suspect anything. (And if anyone does suspect anything, she hasn’t said anything to me. Using “she” because this particular group is all women.) In fact, one who suspects a number of people and listed a few of them off didn’t put me in the list….
With other groups, the people who know what I’m talking about pause, and if they say much of anything, it’s something to the effect of, “Well, that would explain X….”
Kristina Chew, PhD
Jan 16, 2007 at 10:54 pm
I think “know” is the key word—-for myself, “KNOWing” what autism is has enabled me to make sense of past experiences and acquaintances; it is not (as a commenter on the Slate article wrote) the new stand-in label for mental retardation.
Daisy
Jan 16, 2007 at 10:57 pm
Epidemic implies contagion. Autism is not contagious.
Several years ago an administrator told me that autism was overtaking Learning disabilities as the number one disability in our district. He felt that improved diagnostics were not enough to explain the increase.
Autism Vox » What else can we talk about if there’s no autism epidemic?
Jan 18, 2007 at 3:55 am
[…] Definitions: Prevalence and Epidemic […]
Autism Vox » Of Birds and Sheep, and Science in the Media
Jan 30, 2007 at 3:40 am
[…] There is, Illes notes, a “sharp disconnect” between the “conversation” that scientists have with themselves and what the public learns through media stories (and, too, via the Internet, whether in blogs, email discussion lists, or plain old websites). And the volume of stories that the public reads about possible environmental factors causing autism can, indeed, convey a sense that this is the issue—can cause people to flock to ideas (and, indeed, to panic and alarm) about whether or not there is an epidemic of autism, rather than to reflect upon the difference between terms like epidemic and prevalence […]
Autism Vox » New Research, New Books, and New Hopes
Feb 19, 2007 at 5:01 pm
[…] It has not even been two full months into 2007 (a year of great significance for me as, come May 15th, my son Charlie will be 10 years old) and—in the wake of new research studies—some new paths to understanding autism are emerging. On February 8th, the CDC announced new figures for the prevalence rate of autism in the US, which is now 1 in 150. While this was not news to many—a prevalence rate of 1 in 100 has been reported in such places as the UK and in Sweden—the widely publicized lower figure—and in particular New Jersey’s rate of 1 in 94—was a catalyst for many asking “why” and “what do we do” (in New Jersey, six autism bills are being presented to the State Assembly this week). It is possible that autism can be diagnosed even in very young children and that there is a “very early autism phenotype,” according to research in the January 2007 Journal of Autism and Developmental Disorders; early autism diagnosis was also the subject of 60 minutes last night (you can watch the video on the 60 minutes website). Yesterday saw the publication in Nature Genetics of a new study on the genetic causes of autism: As much as 90% of autism may have a genetic basis. […]
Have an opinion? Leave a comment: