IS THERE AN EPIDEMIC
OF AUTISM?
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
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.
China
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.
Denmark
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.
Japan
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.
Russia
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.
Scotland
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.
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Why do more Boys have Autism? fact sheet
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