Fact sheet on alleged epidemic of Autism, an Autism Spectrum Disorder


Sharp rises in the frequency with which Autism is diagnosed has become a concern and debating point in many countries. Members of the medical and scientific community are generally quite skeptical about characterization of the increasing numbers as indicators of an ‘epidemic’. These scientists attribute the dramatic rise in Autism rates to increased awareness of Autism, more effective and inclusive diagnostic criteria and detection tools, noting that the diagnosis of Autism was only created in the 1940s and that the concept of an autism spectrum only entered the mainstream in the 1990s.

The case for believing that cases of Autism are increasing is supported by theories that are not yet backed by rigorous empirical testing. Some of these theories are:
• The tendency for Western women to have their children later
• Exotic infections from travelers and immigrants
• Heavy metal poisoning from pollution
• Changes in diet over the decades.


Scepticism over an Autism epidemic

The sceptical case for an Autism epidemic states that the reason for an increase in diagnoses of Autism Spectrum Disorders is more likely due to be from:
• An increased awareness of the disorders among those making the diagnoses
• Increased awareness among parents now seeking a diagnosis
• Increased screening for Autism
• A broader definition resulting in more diagnoses
• Misdiagnosis (ie. intellectual disability) now termed as Autism.


When psychiatrist Leo Kanner of Johns Hopkins University first described the constellation of symptoms of eight boys and three girls in 1943, he described the novel condition as differing “... markedly and uniquely from anything reported so far.” In Europe, Hans Asperger contemporaneously described a similar syndrome during the same period. Various authors have speculated that genetic causes, pollution, food additives, or childhood vaccinations may play roles. It is clear, however, that at least some part of the rise in diagnoses is due to increased screening, earlier diagnosis, and better recognition. Changes in diagnostic categories in the Diagnostic and Statistical Manual of Mental Disorders affect the numbers diagnosed as autistic, especially changes set out in DSM-III-R,and DSM-IV.


The Autism rights movement also vehemently disputes that any increase in diagnoses be labeled an ‘epidemic’, as this may imply that Autism is a disease.


Diagnostic changes and improvements

The Centers for Disease Control (CDC) in the United States and others have long attributed the dramatic increase in Autism to “better diagnosing” and “greater awareness.” Examples of the meteoric rise in the number of children diagnosed with Autism are common, but hotly debated. For example, the number of students in the United States considered autistic has risen from about 5,200 in 1991 to more than 192,000 in 2005, according to federal education statistics.


The diagnostic criteria used to determine this prevalence were very narrow according to some researchers. At the time, Autism diagnosis was generally based on criteria similar or identical to those outlined by Kanner and Eisenberg (1956):

• A profound lack of affective contact with other people
• Anxiously obsessive desire for the preservation of sameness in routines and environment
• A fascination for objects, which are handled with skill in fine motor movements
• Mutism or a kind of language that does not seem intended for inter-personal communication
• Good cognitive potential shown in feats of memory or skills on performance tests
• Kanner also emphasized onset from birth or before 30 months.


Several epidemiological studies before the 1990s confirmed this level of prevalence across Europe and the U.S. For example, Ritvo et al (1989) found a prevalence of 4 in 10,000 in Utah. Somewhat higher prevalences were found by several Japanese studies.


In the 1990s, Autism began to be recognized as occurring in a broad spectrum of severity. In 1994, Asperger syndrome was included in the DSM-IV. As of 2006, prevalence estimates for autism spectrum disorders (ASDs) stand at sixty in 10,000, or one in 166. Autism Spectrum Disorder is generally thought to include autism, PDD-NOS and Asperger’s syndrome.


Doubt from public health organizations over Autism epidemic

While the number of diagnoses related to Autism has increased in recent decades, public health organizations and researchers have not yet determined whether there is an actual increase in the incidence of autism, or whether more incidents of Autism are being reported now, as a result of increased awareness of the disorder. They also suggest that the diagnosis is being applied more broadly than before as a result of the changing definition of the disorder and that there is ongoing substitution of the ‘autism’ label for less palatable designations such as mental retardation or intellectual disability. They are doubt whether the magnitude of any increase warrants urgent and/or drastic measures.


Whether the true incidence of Autism had been increasing was unclear as recently as 1999. Nevertheless, an increasing prevalence of Autism diagnoses has sparked concerns, especially among parents, which in turn has lead to the initiation of a number of new treatment programs, advocacy groups and support programs. For example, Microsoft became the first major US corporation to offer employees insurance coverage for the cost of behavioral training for their autistic children in 2001.


Parent advocacy groups, such as Safe Minds, A-CHAMP and Generation Rescue, object to public health agencies’ reservations about any urgent action, pointing out that if estimates of the increasing prevalence are true, several of the world’s governments may be confronted with a catastrophic health crisis with deep humanitarian and economic implications. They are calling for increased research into environmental factors that might cause or contribute to Autism, increased research into early interventions and possible cures to treat Autism, and greater funding of programs to help autistic people learn to live with their disorder.


In the absence of a universally accepted etiology of Aautism, many parents, health professionals, politicians and others are demanding further independent study into a number of possible causes for the increase in diagnosis. For example, there is demand for research into a possible causal connection between Autism and the policy of universal, compulsory vaccination schedules. This demand reflects a highly controversial debate on the risks and benefits of vaccinations, pitting the medical community and public health agencies against a large proportion of parents.


Diagnostic changes and improvements


Australia is apparently experiencing a surge in Autism Spectrum Disorders, where a ten-fold rise in diagnoses have been made in the decade to 2006. The Australian Education Department reported a 276 percent jump in students with Autism Spectrum Disorder between 2000 and 2005. As of 2005, a total of 23,083 Victorian students were placed in school disability and language disorder programs, rising 74 per cent from 13,257 students in 2000.



A 2006 U.S. National Institutes of Health study “Epidemiologic Research on Autism in China” stated that “prevalence in China is largely unknown”. Chinese news has claimed that today there are 1.8 million cases of Autism in China and that Shanghai alone has over 10,000 known autistic children.



A study from Denmark was published in November 2002 reporting an increase in prevalence from 2 cases per 10,000 in the 1980s, to more than 10 per 10,000 in 2000. In Denmark, 738 cases were found from 537,303 children (or 1 in 728 children), far less than estimates of up to 1 in 86 among primary school children in the United Kingdom and around one out of 150 children in the US.

It was also noted that for the period 1971-1990, where thimerosal-containing vaccines were administered, there was no increase in prevalence, but that after its use was discontinued in 1992 there was an increase in prevalence. They concluded that their “study provides strong evidence against the hypothesis that MMR vaccination causes Autism”. However, according to Robert F. Kennedy, Jr., “before banning (thimerosal), Denmark registered only autistics who were hospitalized — one fifth of the afflicted populations.


After the withdrawal of thimerosal, Denmark began counting out-patient autistics in its registries. The resulting spike in raw numbers therefore made it appear that Autism rates actually increased after the withdrawal of thimerosal.” However, Kennedy's explanation is inaccurate, because the spike in incidence started in 1991, well before the change in registration of cases in 1995. The same increased incidence between 1991 and 2000 was also found when restricting the analysis to only persons who would have been recorded under the older criteria. The 2002 Danish epidemiological study was a consideration in the 2004 U.S. Institute of Medicine (IOM) Special Committee decision, which concluded that a connection between MMR vaccination and Autism did not exist.



A study released in early 2005 was the first to examine Autism trends before and after the 1993 withdrawal of MMR from the Japanese market, inclusive of children who had not had the three-in-one jab. The MMR was withdrawn in Japan in a crisis of confidence after the mumps component was linked to meningitis. The study's authors reported 48 and 86 cases per 10,000 children in two sequential years prior to withdrawal, doubling to 97 and 161 per 10,000 afterwards in two sequential years afterwards. They conclude “The significance of this finding is that MMR vaccination is most unlikely to be a main cause of Autism Spectrum Disorder, that it cannot explain the rise over time in the incidence of Autism Spectrum Disorder”.

Dr. Wakefield has noted the specific year to year data shows a dip in Autism diagnoses after Japanese public confidence fell in the MMR specifically, and vaccinations generally. Wakefield notes Autism rates had risen to 85.9 per 10,000 for children born in 1990, but declined to 55.8 per 10,000 for children born in 1991 when MMR uptake declined before the MMR vaccine’s withdrawal. Autism rates have steadily increased since that time, after the Japanese public began to accept the notion of three separate vaccines and refinements to diagnostic criteria.



Thimerosal was banned in Russia from children's vaccines by 1985, in response to a study performed in 1977. Despite this, the Russian Autism rate did not change for at least a decade.


United Kingdom

An estimate of the UK incidence rate of autism spectrum disorders from the National Autistic Society disorders in the total population was one in 110. A 2001 review, by the Medical Research Council, yielded an estimate of one in 166 in children under eight years of age. Bernard Rimland cited statistics he claimed showed the Autism rate in the UK suddenly spiked after the first introduction of the MMR vaccine in 1989, just as it had after the MMR’s introduction in the US in the late 1970s.This is not consistent with evidence published in the British Medical Journal.

Substantial funds (over £3 million) were spent in the UK on a pro-MMR campaign. Concerted efforts have been made by the British government and pharmaceutical industry interests to negate the widely criticized 1998 study, led by Dr. Wakefield, that showed a consistent set of bowel disorders among a dozen autistic children. The study authors also suggested the need for further studies into the apparent link between MMR and Autism, although 10 of Wakefield’s co-authors retracted the recommendation six years later.



Among the predominantly industrialized nations affected by reports of an Autism epidemic, Scotland is sometimes cited as a possible epicenter. The number of schoolchildren diagnosed with Autism in Scotland has surged significantly over the past six years, with an increase of more than 600 per cent among secondary school students. In 1999, there were 114 children with Autism diagnoses in state secondaries, compared with 825 in 2005. Over the same period, the number of autistic youngsters in primary schools more than quadrupled, from 415 to 1,736.


United States

After years of substantial annual increases, provisional data from the US Department of Education show a significant decrease in the number of new Autism diagnoses recorded among children 3 to 5 years old. There were 1,451 new cases in 2001-2002; 1,981 in 2002-2003; 3,707 in 2003-2004; and 3,178 in 2004-2005, a drop of 529 new cases, or 14%.


According to a recent ‘conservative’ estimate, there are approximately 500,000 autism spectrum cases in the United States, including perhaps as many as 1 in 150 children. Autism is the fastest growing population of special needs students in the US, having grown by over 900% between 1992 and 2001, according to data from the United States Department of Education. In 1999, the Autism incidence rate in the US was generally cited at 4.5 cases per 10,000 live births. By 2005, the US Centers for Disease Control (CDC) estimates one of every 250 babies is born with Autism, or 40 cases per 10,000.


The rising enrollments in special education classes were examined in a 2006 Pediatrics journal article. During the period between 1994 and 2003, as Autism diagnoses rose, diagnosis of intellectual disability and learning disabilities dropped sharply. This study also found that prevalence data taken from special education enrollment revealed numbers of diagnoses significantly less than epidemiologic estimates.


As many as 1.5 million Americans may have some form of Autism, including milder variants, and the number is rising. Epidemiologists estimate the number of autistic children in the US could reach 4 million in the next decade.


This button closes all Autism information fact sheets on this site

Click here for the full range of Asperger's and Autism fact sheets at www.autism-help.org
Click here to see the Why do more Boys have Autism? fact sheet
This autism fact sheet is licensed under the GNU Free Documentation. It is derivative of an Autism and Asperger's syndrome-related articles at http://en.wikipedia.org

Scientists are tending to attribute the dramatic rise in Autism rates to increased awareness of Autism, more effective and inclusive diagnostic criteria and detection tools