Is there an autism epidemic?
The U.S. Centers for Disease Control and Prevention says 1 in 88 children is now diagnosed with autism. We asked autism experts the question: Is there an autism epidemic?
This response is from Catherine Lord, who is part of the American Psychiatric Association’s working group responsible for updating the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM), a guide used by physicians around the world. The latest edition will include a new definition of autism.
Catherine Lord, director of the Center for Autism and the Developing Brain (a collaborative program between New York-Presbyterian Hospital, Weill Cornell Medical College and Columbia University, in partnership with the New York Center for Autism):
The number of children identified as having autism spectrum disorders has clearly been increasing for the last 30 years, with the steepest increases in the last 15 years. Some of this increase is accounted for by diagnostic substitution. That is, children who once received diagnoses of mild intellectual disability or receptive-expressive language disorder are now recognized as having autism spectrum disorder.
However, this shifting only accounts for a small proportion of the increase in numbers. Some of the increase is accounted for by increased awareness and access to services. We can see this in the U.S. Centers for Disease Control numbers, because parents who are not native English speakers, parents who have less education and families in regions with fewer services all have significantly fewer children with ASD in studies, something that seems very unlikely in reality.
We also know that from (the 1987) DSM III-R on, with broader references to difficulties in social reciprocity, as opposed to references to much more severe “lack of social awareness,” that the concept of autism has broadened. However, all of these factors do not necessarily add up to the very large numbers of children being identified now.
A recent study in the U.K., using similar standardized diagnostic methods to those in many other studies in Canada, the U.S. and Europe, found that 1 in 100 adults met diagnostic criteria for ASD, most of whom had never received an ASD diagnosis, though most of them were receiving some kind of psychiatric or social support, and many were not employed or living independently.
If 1 in 100 adults has ASD, then this would not suggest that the numbers of young children are not increasing as much as that, with careful searches, we are doing a better job of finding people with ASD — both children and adults (in that particular study, not necessarily in other circumstances).
Another research finding that suggests caution is that there is very large variation in how many children are identified with ASD in the U.S. in the CDC studies, and even in the baby sibling research projects, where methods are similar and researchers are all well-trained. My bias, as a clinician who works with families with family members with autism, is that most of the variation is accounted for by underestimates — that is, in some areas of the U.S. we are still missing many children, particularly children who are not in the famous “1 per cent” of affluence, with ASD or misdiagnosing them as having other disorders. However, I know that I am biased.
With adults and with the baby sibling studies, it is harder to know what is going on. Our clinic does see some self-referred adults hoping to get diagnoses of ASD that they can use to account for life problems such as marital problems or job losses or problems with the law, when ASD is not appropriate. In contrast, we also regularly see adults whom we do diagnose with ASD who have never received an autism diagnosis before but have clearly struggled with the difficulties associated with autism since early childhood, and just never had a good assessment. For children, my experience is that far fewer families seek diagnoses of ASD when they are not appropriate.
Putting this information together, I do not believe that we can rule out the possibility that the numbers of children with autism are increasing beyond diagnostic substitution and increased awareness, but we need to be very careful how we study these changes.
As a former Edmontonian and proud wife and mother of Canadians, I can proudly say that the Canadian health and social systems are much more uniformly accessible within provinces than these services in the U.S. and offer an opportunity to figure out what the true nature of these changes in numbers mean.
I avoid the use of the word “epidemic” because it has connotations of contagion and fear, which I do not think are helpful for families. But I think we need to understand what is happening.