Is there an Autism Epidemic?

Autism is the fastest-growing developmental disorder in the world, with the prevalence of diagnosis having increased by 600 per cent over the last 20 years, says Frank Viti, chief executive officer, Autism Speaks Canada 

In 1975, the prevalence number was 1 in 5,000; in 2001 it was 250; in 2012, the prevalence number has jumped to 1 in 88. As Bob Wright, co-founder of Autism Speaks, was quoted as saying, “We have an epidemic on our hands. The costs are staggering and will continue to rise as prevalence continues to increase.”

In the U.S., autism costs society $126 billion per year, which has more than tripled since 2006. With the new prevalence number of 1 in 88, this will jump to $137 billion.

Although there are some positive signs that show an increase in awareness of autism spectrum disorders as well as better detection and reporting of autism, these positive signs come with a need for programs and services to assist those affected by autism. There is also a greater need for access to treatment as the prevalence numbers increase. With this extra awareness, detection and reporting comes an increased need for funding.

Accessibility is also a problem. There are long wait times for diagnosis, and then it is a struggle to secure the appropriate educational services and therapies such as speech, behaviour and occupational therapies that are important to the development of someone on the spectrum. There is also a greater need to make ABA and IBI therapies more accessible. Canada’s Standing Senate Committee on Social Affairs, Science and Technology reported that in 2007, families were paying more than $60,000 a year on autism therapy.

We all must keep in mind that autism is not something you grow out of. There are thousands of adolescents and adults living with autism and there are not enough resources to help them find housing and employment so that they can lead meaningful and fulfilling lives with the same opportunities that their typically developing peers have. In 2007, the Standing Senate Committee reported that there were more than 144,000 Canadian adults on the spectrum and 48,000 Canadian children. As these young children with autism grow up, they will contribute to the increasing number of the already underfunded and under-resourced adult population on the spectrum. Much more attention needs to be paid to developing programs and services that will help those adults on the spectrum now and to prepare for those who will enter adulthood on the spectrum down the road.

Autism places a tremendous financial and emotional burden that families must confront on a daily basis as they battle this disorder. They need resources to help lessen the constraints that they face in accessing diagnosis, treatment, programs, services and therapies. Costs need to be reduced and access increased, and until there is more substantial evidence that this is happening, autism will be an epidemic in our society.

Jonathan Weiss, Canadian chair in autism research, York University professor:

What a lot of people are saying is there are many reasons why those rates are higher than they were before. One of the major things we are realizing . . . is the complexity around this and that it really is a spectrum of difficulties. Before, we were looking for one specific type of person or look. Now we are seeing things much more broadly. So I think that awareness, better ability to diagnose, better measurement and better ability to track exactly what’s happening might be a lot of the things that are related to the newer numbers relative to older numbers.

When it comes to the cause of this, I’m not the best person to answer that because I’m not looking at the genetics or the environmental influences on the genetics of a very complex disorder.

Awareness, more ability to diagnose and better-trained professionals across Canada and in the U.S. are recognizing many of the people who before weren’t being recognized.

Stephen Scherer, Director, University of Toronto McLaughlin Centre and The Centre for Applied Genomics, Hospital for Sick Children:

The Autism and Developmental Disabilities Monitoring Network of the U.S. Centers for Disease Control (CDC) has surveyed the prevalence of autism spectrum disorder (ASD) among 8-year-olds from up to 14 U.S. centres every two years since 2000. The most recent analysis pertains to the 2008 cohort, estimating overall prevalence as 1 in 88 children — almost double that of the original, 2000 cohort. So I suppose this substantial observed increase would indeed support the possibility of an autism epidemic, with the caveat that these data cannot distinguish the proportion of the increase attributable to changes in case ascertainment, as opposed to a true increase in ASD prevalence.

Our colleagues in Montreal, Drs. (Mayada) Elsabbagh and (Éric) Fombonne, undertook a comprehensive survey of epidemiological reports to catalogue the global prevalence of ASD and found that it is often under-recognized, particularly in the developing world. Variation in prevalence estimates is largely accounted for by variability in ascertainment and measurement, but environmental exposures may also play a role.

All of these data and my own observations lead me to believe that ASD prevalence is rising incrementally, but that so far there has not been an outbreak, nor is it pandemic. We now know from both the genetic and clinical sense that ASD is highly heterogeneous, so there are many targets or paths that can trigger or lead, respectively, to a diagnosis of ASD. Add to this mix the many new selective pressures being imposed on our brain’s development by the information-based society we now live in, and these phenomena too may account for some of the increase we see in ASD prevalence.

Temple Grandin, one of the world’s most accomplished and well-known high-functioning autistic adults. She is an animal sciences professor at Colorado State University, author and livestock industry consultant on animal behaviour:

Mild autism or Asperger’s has always been here. I’ve worked in a technical industry for 40 years and . . . they’re everywhere. They just used to call these people nerds before . . .

One of the things that helped them (succeed) is that in the 1950s, they taught social rules. Kids were taught table manners, how to shake hands, how to say please and thank you. That was just taught to all children in the ’50s. So they were better able to cope in society.

However, I think severe autism — where children remain non-verbal into adulthood — has increased. I don’t think the total increase would be just the previously undiagnosed Asperger’s. That would probably only be half of it.

Environmental contaminants could be one (explanation). Older parents could also be a factor. One of the problems that a male has is that when he gets older, his sperm has to be copied every two weeks. He makes a copy of a copy of a copy. So as he ages, you get copying mistakes. Women have all their eggs from birth. They are not copied constantly . . .

Kids (today) don’t get enough exercise, they don’t have enough omega 3 in their diets . . . In the ’50s we ate a lot more wild fish. Also, there is more mercury and solvents in the environment.

The other thing is there are a lot more psychiatric and other types of drugs taken during pregnancy. Epilepsy drugs, anti-depressant drugs, a lot of these drugs weren’t taken during the ’50s.

Mike Lake, whose now 17-year-old son, Jaden, has autism, is Conservative MP for Edmonton-Mill Woods-Beaumont:

I’ll leave that question for the scientists to answer. But when you are looking at those numbers I would certainly say that there is a combination. We are doing a better job of recognizing it. So there’s a better job of diagnosis. So that certainly plays into those numbers. But I do believe — and I think if you talk to most families that live with someone with autism — that we would recognize more of it in society as well. So I think you are seeing a combination of the two.

We need to continue with the momentum that we are building. Right now for example in Canada we have some of the best researchers in the world. Talking to Jonathan (Weiss), I have no reason to believe he won’t be another one of those researchers. There is some phenomenal research going on right now. You see Stephen Scherer in Toronto on the Autism Genome Project, really taking a leadership role worldwide with that. Someone like Lonnie Zwaigenbaum and Susan Brison. That list is long and it’s getting longer all the time . . .

Then there is the treatment side of things. And of course most of the treatment in this country falls to the provincial level, so a big part of the equation is getting out to the provincial elected officials and first of all educating them on what autism is because I still don’t think everybody understands exactly what it is and what the challenges are . . . (Then) they can make the right decisions in terms of funding for not only treatment for kids, which tends to be a big focus, but recognizing that autism is a lifespan issue. People with autism live just as long as you or I . . . so there are transitions into school, out of school into the work environment. And then housing challenges and what happens with these kids that become adults that become seniors when we’re gone as parents. That’s a question that all parents grapple with.

Dr. Evdokia Anagnostou, child neurologist, clinician scientist, Bloorview Research Institute; assistant professor, department of pediatrics, University of Toronto:

There is no doubt that the rate of diagnosing autism spectrum disorders (ASD) has been increasing . . .

The question remains whether the increase in the diagnosis is due to a true increase in the incidence of autism spectrum disorder (the true risk of developing ASD) or whether other methodological factors account for this increase.

Possible culprits include changes in the diagnostic criteria, making the diagnosis earlier and earlier so that younger kids are included in the numbers, diagnostic substitution (we diagnose more ASD now than global developmental delay or language disorders compared to one to two decades ago), and increased awareness of the diagnosis, so that teachers, parents and front-line clinicians are more likely to look for signs and symptoms of ASD. All of these would have been predicted to increase the number of children diagnosed, and have been shown to do such in various studies.

The question still remains, after all of this is accounted for, is is there a true increase in the incidence of the disorder?

We do not know the answer to that yet, but that does not mean that we should not be investigating this possibility. Specifically, although we know that ASDs have a strong genetic component, and we absolutely need to understand that more fully so that we can understand the biological paths that may be potentially targets for treatment, there are factors within and out of the human body that influence the degree of gene expression.

In other words, although children with autism carry genetic variations that either cause ASD or increase the risk of ASD, there may be interactions with the environment, whether this is the environment around conception (e.g., recent data related to paternal age), fetal environment or the environment outside of the body that may influence how these genes ultimately affect the function of brain and other biological networks.

As such, studies of the epidemiology of ASD, as well as our genome and gene-by-environment relationships, are still critical to fully answer this question.

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.

"One in 88 children are now diagnosed with autism"

Is There an Autism Epidemic?
by Dr. Steven Novella

There is no question that the rates of autism diagnosis have been increasing in the US and the Western world. The latest Centers for Disease Control (CDC) estimates indicate that 1 in 88 children have been diagnosed as being on the autism spectrum (1/54 boys and 1/252 girls). This is up from just two years ago when the estimate was 1/100 children, and much higher that the 1990s when estimates were around 1/250.  

It certainly looks like we are in the middle of an autism epidemic, but experts are not so sure, and for good reason.  

As a general rule in any scientific discipline when a measured quantity is changing over time you have to consider the possibility that the method of measurement is changing, rather than the thing being measured itself. In medicine this often relates to the method of diagnosis. To be precise we often say the rate of diagnosis is increasing (or decreasing), rather than the rate of the disease - unless all diagnostic artifacts have been reasonably ruled out.  

Autism is particularly susceptible to diagnostic artifacts. Various factors have been identified that could, and probably are, affecting the rate at which the autism diagnosis is made.  

The first is an expansion in the diagnosis itself. In fact autism is part of what is now called autism spectrum disorder, because we recognize that it exists along a fairly broad spectrum. If you cast a wider net, you're going to catch more fish - that doesn't mean there are more fish.  

Related to this issue is the fact that autism is a clinical diagnosis - it's based on recognizing a set of signs and symptoms. At present there are no biological markers that can be used to reliably diagnose autism. There is therefore no laboratory confirmation or objective result that can be used to compare prevalence over time. Clinical judgment is required, and that judgment can drift over time.  

Awareness and familiarity with autism can therefore also lead to more diagnoses. Teachers may be more likely to consider the diagnosis and raise the issue with parents, and doctors may be more likely to make the diagnosis.  

Yet another related issue is so-called diagnostic substitution. There are several related diagnoses the may be more likely to be diagnosed as autism today. Two or three decades ago, however, the same children might have been diagnosed with a non-specific developmental disorder, or a language disorder.  

Surveillance is another issue - the effort being made by school systems and others to identify children who have special needs because they fit on the autism spectrum.

The scientific evidence strongly supports a major role for all these various factors in explaining the increase in autism diagnosis. Studies have shown that there is diagnostic substitution (as autism diagnosis goes up, other related diagnoses go down), there is increased surveillance, and there is wider recognition of autism. The chance of having a child diagnosed with autism strongly corresponds to living near other families with a child on the spectrum, and being in the same school system. Therefore social contact with others with the diagnosis increases the chance of being diagnosed.  

Several studies have shown that when the same methods are used to compare different cohorts of children born at different times, the autism prevalence is the same. Further, the prevalence of autism in different age groups (when the same surveillance and diagnostic methods are used) appears to be the same. If the true incidence of autism were increasing then younger age groups would have a higher prevalence.  

It is possible, therefore, from these various factors that the apparent rise in autism is entirely an artifact of diagnosis and surveillance. It is difficult to prove this, however, and so there is always a certain amount of uncertainty. It is also possible that there is a real increase in the incidence of autism over time, but there is no data that establishes that there is a real increase beyond the factors described above.  

Of course there are some groups that are invested in the notion that autism is truly increasing and represents an epidemic. Most notable is the anti-vaccine movement, who over the last decade have been blaming the increase in autism on vaccines. Initially they blamed autism on the MMR vaccine, but the scientific data did not support that claim, and the credibility of the originator of this fear, Andrew Wakefield, has since crashed and burned.  

After the MMR hypothesis failed they next turned to mercury in the form of thimerosal in some vaccines. They confused correlation with causation by arguing that autism rates were increasing as the vaccine schedule also increased. By the end of 2002, however, thimerosal was removed from the routine vaccine schedule in the US, and therefore the amount of exposure to thimerosal plummeted. Advocates of the thimerosal hypothesis (such as David Kirby) predicted that autism rates would also plummet.  

They were correct in that, if thimerosal were a significant contributor to autism then the rates should drop considerably once thimerosal was largely removed from childhood vaccines (it was still present in some flu vaccines). Since 2002, however, autism diagnosis rates have continued to increase at the same rate. We are now 10 years later, and there is simply no justification for clinging to the thimerosal hypothesis any further (of course this hasn't stopped antivaccinationists).  

Ironically the antivaxers are now using the continued increase in autism diagnosis to argue that vaccines cause autism, even though that increase contradicts their prior predictions.  

The data clearly shows that much, if not all, of the increase in autism is due to expanded diagnosis and surveillance. It is still possible that there is a real increase, but more research would be needed to establish that.  

However, regardless of cause, we now know that autism is very common. It therefore deserves a proper level of attention and resources, both for research and services for those on the spectrum.

Steven Novella, M.D. is the JREF's Senior Fellow and Director of the JREF’s Science-Based Medicine project.

Dr. Novella is an academic clinical neurologist at Yale University School of Medicine. He is the president and co-founder of the New England Skeptical Society and the host and producer of the popular weekly science show, The Skeptics’ Guide to the Universe. He also authors the NeuroLogica Blog.

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