Epidemic never was
New Scientist magazine
The Autism Epidemic that Never Was
RICHARD Miles will never forget the winter of 1989. The 34-year-old
company director and his family spent that Christmas on the island of
Jersey in the English Channel, where he had grown up. It was also then
that he first noticed something was badly wrong with his 14-month-old
son Robert. The bright, sociable child, who had already started
talking, became drowsy and unsteady on his feet. Then he started
bumping into furniture. Within weeks his language had dried up and he
would no longer make eye contact. "It was as if the lights went out,"
says Miles. His son was eventually diagnosed with autism.
Miles, who now campaigns for more research into autism, is convinced
that his son is part of an autism epidemic. Ten years ago, he points
out, Jersey had just three autistic children in special-needs
education. It now has 69. Robert was one of a cluster of nine children
on the island diagnosed around the same time.
Similar rises have been reported across the world, from Australia to
the US, and from Denmark to China. Back in the 1970s, specialists
would typically see four or five cases of autism in a population of
10,000. Today they routinely find 40, 50 or even 60 cases. Perhaps the
starkest illustration of autism's relentless rise comes from
California. In 2003, the state authorities stunned the world when they
announced that over the previous 16 years, the number of people
receiving health or education services for autism had risen more than
sixfold. The world's media went into overdrive.
What could be causing so many children to lose their footing on a
normal developmental trajectory and crash-land into the nightmare
world of autism? The change has occurred too suddenly to be genetic in
origin, which points to some environmental factor. But what? There is
no shortage of suspects. In the UK, blame is often laid at the door of
the combined measles, mumps and rubella (MMR) vaccine. In the US,
mercury added to a range of childhood shots has been accused. Food
allergies, viral infections, antibiotics and other prescription drugs
have all been fingered, often by campaign groups run by mystified and
angry parents. The problem is that none of these suggested causes has
any solid scientific evidence to support it (see "The usual
suspects").
Perhaps there's a simple explanation for this: there is no autism
epidemic. On the face of it that sounds ridiculous - just look at the
figures. But talk to almost any autism researcher and they will point
to other explanations for the rise in numbers. Some say it's still an
open question, but others are adamant that the autism epidemic is a
complete myth. And if the most recent research is anything to go by,
they could be right. Studies designed to track the supposedly
increasing prevalence of autism are coming to the conclusion that, in
actual fact, there is no increase at all. "There is no epidemic," says
Brent Taylor, professor of community child health at University
College London.
Autism is a developmental disorder sometimes noticeable from a few
months of age but not usually diagnosed until a child is 3 or 4 years
old. It is characterised by communication problems, difficulty in
socialising and a lack of imagination (see "What is autism"). It is
not a single disorder, but comes in many forms, which merge into other
disorders and eventually into "normality". There is no biochemical or
genetic test, so diagnosis has to be made by observing behaviour.
Autistic children also often have other medical conditions, such as
hyperactivity, Tourette's syndrome, anxiety and depression. The upshot
is that "one person's autism is not another person's autism," says
epidemiologist Jim Gurney of the University of Minnesota in
Minneapolis.
In recognition of this ambiguity, autism is considered part of a
continuum within a broader class of so-called "pervasive developmental
disorders" (PDDs) - basically any serious abnormality in a child's
development. Autism itself is divided into three categories: autistic
disorder, Asperger's syndrome (sometimes called "high-functioning
autism"), and pervasive developmental disorder-not otherwise specified
(PDD-NOS), sometimes called mild or atypical autism. Together these
three make up the autistic spectrum disorders.
"Californian authorities stunned the world when they announced a
sixfold rise in autism over the past 16 years"
Confused? You're not the only one. The difficulty of placing children
with developmental problems on this spectrum has led to several major
shifts in the way autism is diagnosed in the past 30 years. In the
late 1970s, the autism label was kept for those with severe problems
such as "gross language deficits" and "pervasive lack of
responsiveness". But since 1980 the diagnostic criteria have been
revised five times, including the addition of PDD-NOS in 1987 and
Asperger's in 1994.
This massive broadening of the definition of autism, particularly at
the milder end of the spectrum, is one of the main factors responsible
for the rise in cases, says Eric Fombonne of McGill University in
Montreal, Canada, a long-standing sceptic of the epidemic hypothesis.
Tellingly, around three-quarters of all diagnoses of autism today are
for Asperger's and PDD-NOS, both of which are much less severe than
the autism of old. "There is no litmus test for who is autistic and
who is not," says Tony Charman of the Institute of Child Health at
University College London.
Changes in diagnostic criteria apart, there are other reasons to
believe that autism is simply being diagnosed more often now than in
the past. One is the "Rain Man effect" - the huge increase in the
public awareness of autism following the 1988 film starring Dustin
Hoffman. Awareness has also increased massively among healthcare
workers. "Twenty years ago there were maybe 10 autism specialists in
the country. Now there are over 2000," says Taylor.
Another factor is that one of the stigmas of autism has largely
disappeared. Until about 10 years ago a prominent idea was that autism
was caused by an unloving "refrigerator mother". Now it is a no-blame
disease. "Parents are more willing to accept the label," says Taylor.
One expert New Scientist spoke to went as far as to describe autism as
"trendy".
Finally, while some parents still have to fight for help for their
autistic children, far more services are now available. This has
encouraged doctors to label borderline or ambiguous cases as autism -
they know this is often the best way to get the child some help. It
also makes autism an attractive diagnosis for parents. "I hear stories
of parents who are anxious to get a particular diagnosis if that is
what is required to obtain the services their child needs," says
Sydney Pettygrove, a paediatrician at the Arizona Health Sciences
Center in Tucson. In the UK, says Simon Baron-Cohen of the Autism
Research Centre at the University of Cambridge, "in every town there
are trained clinicians who can make a diagnosis."
It is hard to quantify these trends, but many epidemiologists now
believe that they can account for the apparent rise in autism the
general public and media take for granted. Proving it, however, is
difficult - if not impossible. The main problem is that an
epidemiological study carried out in the 1980s simply cannot be
compared with one done last week. There will be so many differences in
diagnostic procedures and in the willingness of doctors and parents to
label a child autistic that comparisons are meaningless. "You can't
control for everything," says Charman.
And so attention has shifted to what epidemiologists sniffily refer to
as "service provider data", such as the California figures. Ever since
1973, the authorities there have been keeping records of the number of
people receiving some kind of state help in connection with autism. In
2003, California's Department of Developmental Services (DDS)
announced a chilling figure that captured the world's attention. In
the 16 years to 2002, cases rose from 2778 to 20,377 (see Graph).
Among autism campaigners these figures are often cited as
incontrovertible and final proof of the existence of the autism
epidemic.
But there are serious problems with this interpretation. First, the
figures are raw numbers from public services, not a proper
epidemiological study. Critics point out they are not corrected for
changes in diagnostic criteria or for the growing awareness of autism.
"Prisons and institutions could be full of autistic adults labouring
under wrong diagnoses such as schizophrenia"
There is evidence, for example, that as the California autism numbers
have risen, diagnoses of mental retardation have fallen. Researchers
at Boston University School of Medicine in Massachusetts have found a
similar pattern in the UK. This effect, dubbed "diagnostic
substitution", cannot explain all the increase but is one example of
how diagnostic fashions can skew the data.
Another potential flaw is that the California figures don't take into
account the fact that the state's population is growing rapidly.
Between 1987 and 1999, the total population rose by nearly 20 per
cent, and the age group 0 to 14 rose even more steeply, by 26 per
cent.
As a result of these doubts and unknowns in the California figures,
most epidemiologists refuse to draw firm conclusions from them. "The
report doesn't change anything," says Charman. "It's not a systematic
study." In fact, the preface of the most recent California report
contains a health warning not to read too much into the numbers. "The
information should not be used to draw scientifically valid
conclusions," it says.
Some researchers, notably Robert Byrd of the MIND Institute at the
University of California, Davis, have attempted to correct for all the
unknowns. In an analysis published on the state DDS website nearly
three years ago, Byrd concluded that the rise is real. "Autism rates
are increasing," he told New Scientist. Some scientists accept that
Byrd's analysis lays to rest the idea that population growth could
have significantly swelled the figures. But his methods for
investigating the other potential sources of bias have been heavily
criticised, and tellingly, Byrd has not yet succeeded in getting his
study published in a peer-reviewed journal. Until he does, it is hard
to know how much weight to give his conclusions.
Perhaps the strongest case against the "better diagnosis" theory is
that, if true, there should be a "hidden hoard" of autistic adults who
were never properly diagnosed in childhood. To parent Richard Miles,
this is compelling. "My doctor cannot believe that he could have
missed so many cases in the past," he says. But Taylor disagrees. As a
former general practitioner, he says there are many children today
diagnosed with autism who would not have been labelled as such in the
past.
This view is difficult to substantiate, but in 2001 a team led by
Helen Heussler of Nottingham University, UK, had a crack. They
re-examined the data from a 1970 survey of 13,135 British children.
The original survey found just five autistic children, but using
modern diagnostic criteria Heussler's team found a hidden hoard of 56.
That's over a tenfold rise in numbers, which puts the California
figures in perspective. Heussler and her colleagues concluded that
"estimates from the early 1970s may have seriously underestimated the
prevalence".
Lorna Wing, a veteran autism researcher at the Institute of Psychiatry
in London, agrees. In the 1970s she spent a lot of time working with
special-needs children in the London district of Camberwell. Wing
reckons that at the time, fewer than 10 per cent of autistic children
were correctly diagnosed. She also thinks that prisons and
institutions are full of autistic adults labouring under wrong
diagnoses such as treatment-resistant schizophrenia or ADHD.
Ultimately, however, it may be impossible to tell whether there has
been a genuine rise in the incidence of autism over the past 30 years.
"There is no clear evidence that there has been an increase, but
there's no proof that there hasn't," says Charman. Even the
arch-sceptic Fombonne accepts this. "We must entertain the
possibility," he says. "But we don't have the evidence."
But researchers can answer another question: is the incidence of
autism continuing to rise? There is a tried and tested method of
tackling this sort of question. You carry out a large prevalence study
among a particular age group, and then repeat it a few years later
with a new set of individuals, in the same place and using exactly the
same methods. Several such studies into autism are ongoing, notably
one funded by the US Centers for Disease Control and Prevention in
Atlanta, which will look at changes in incidence across 11 states.
One team, however, is ahead of the game. Back in July 1998, Fombonne
and Suniti Chakrabarti of the Child Development Centre in Stafford,
UK, started screening every child born in a four-year window (1992 to
1995) who lived in a defined area of Staffordshire, 15,500 children in
total. As a result, they established baseline figures for autistic
spectrum disorders - about 62 per 10,000. Then they did it again, in
exactly the same place and exactly the same way, this time with all
the children born between 1996 and 1998. In June this year, they
reported that the prevalence of autism was unchanged (American Journal
of Psychiatry, vol 162, page 1133). "This study suggests that epidemic
concerns are unfounded," concludes Fombonne.
Similar surveys need to be done in other parts of the world to rule
out the possibility that there is something unusual about
Staffordshire. And the Staffordshire result has failed to convince
campaigners and parents, including Miles. But what is clear is that
after the first direct test of whether autism is rising, it's 1-0 to
the sceptics.
That doesn't mean we should stop searching for the causes of autism.
The disorder itself is real, and if researchers knew what was behind
it much suffering could be averted. But the Staffordshire surveys do
suggest that there is no environmental problem that is triggering
autism in ever-greater numbers and which must be identified as a
matter of urgency. That will not be much comfort to families with
autistic children. But it should make everyone else feel a bit more
secure.
What is autism?
The developmental disorder that is now called autism was first
described by doctors in 1943. Psychiatrists say there are three key
features: lack of imagination, communication difficulties, and
problems interacting with others. In practice, those affected have a
bewildering range of strange behaviours. These can include fear of
physical contact, hearing and visual problems, bizarre obsessions and
a touching inability to lie.
Apart from the fact that about three-quarters of those affected are
male, it is hard to make generalisations because the condition varies
widely between patients. Contrary to popular belief, freakish talents
for maths or music, say, are uncommon. In fact, about three-quarters
of people with autism have learning difficulties, but those who do not
may manage to hold down a job.
Parents usually realise something is wrong because children fail to
develop normally. But up to one third of cases are "regressive" -
children seem to go backwards when they are about two, losing their
language and social skills.
In psychological terms, people with autism seem to lack "theory of
mind" - the recognition that other individuals may hold a different
perspective on things than themselves. This leaves them in a
bewildering world where people seem to act according to
incomprehensible rules and behave in meaningless ways. They also have
impaired "executive function", the ability to plan future actions. And
patients have weak "central coherence", the ability to extract meaning
from experiences without getting bogged down in details. In other
words, they can't see the wood for the trees.
Clare Wilson
The usual suspects
Both genes and environmental factors play a role in the development of
autism. But if there has indeed been a sudden rise in cases, the only
possible cause is an environmental change because our genes can't be
altering that fast. Numerous candidates have been proposed.
"LEAKY GUT"
Thanks partly to anecdotal reports linking autism with bowel problems,
some researchers believe that the condition could be caused by various
dietary components leaking through the gut wall into the bloodstream,
allowing them to reach the brain. One possible cause could be
increased use of antibiotics disturbing the natural balance of gut
bacteria.
There have been some reports of people with autism doing better on
diets that exclude dairy foods and gluten, a protein found in wheat
and barley. And a few small studies have found that some patients seem
to improve after injections of the gut hormone secretin, which could
possibly be related. But neither of these approaches have been borne
out by larger placebo-controlled trials.
MMR JAB
The combined measles, mumps and rubella (MMR) vaccine was fingered by
gastroenterologist Andrew Wakefield, formerly of the Royal Free
Hospital in London. He suggested that giving children three vaccines
simultaneously could damage their gut. Along with vociferous
campaigning by parents, this led to a fall in uptake in the UK of this
important childhood vaccine.
However, numerous large-scale studies showed no link between receiving
the vaccine and developing autism. A recent study from Japan may prove
the final nail in the coffin for the MMR theory. It found that
diagnosed cases in that country continued to rise even after the
triple jab was withdrawn (Journal of Child Psychology and Psychiatry,
vol 46, p 572).
MERCURY IN VACCINES
In the US, mercury is public enemy number one. The mercury-containing
preservative thimerosal - which has been used in a range of childhood
vaccines although it is now being phased out - is claimed to cause
autism by damaging the developing brain directly. But a review last
year by the US Institutes of Medicine rejected a causal link between
autism and either mercury or the MMR jab.
Clare Wilson
--------
How nice to finally get that cleared up.
Autism Diva
Told you so
posted by Autism Diva at 9:44 PM
6 Comments:
Blogger Kev said...
Suniti Chakrabarti of the Child Development Centre in Stafford,
UK
Well I'll be....thats the guy who diagnosed Megan (he retired
last year) and thats where she was diagnosed, as well as being
the town I live in.
If only I'd known he was an internationally famous researcher
I'd have asked for his autograph!
5:28 AM
Blogger Autism Diva said...
I've seen the name Chakrabarti many times, usually with
Fombonne's name.
Interesting! It's nice that Megan has had at least one very
good doctor, Autism Diva hopes her other doctors are as good.
6:55 PM
Blogger maelorin said...
not being a subscriber to new scientist, and being busy
recently, i was only able to post the preview link during the
week.
while the mmr issue has been addressed by 'hard' science now, i
doubt the crusade will stop. too many people tooo heavily
emotionally invested [embarrassment will prevent them from
backing down gracefully.]
in one sense, this whole debarcle exposes just how badly the
general population have been 'educated'. too much emphasis on
crap that doesn't improve anyone's understanding of the world.
too busy indoctrinating and filling heads with stuff for
employers.
6:59 PM
Blogger azgma said...
I LOVED the article. I am an Arizona Licensed psycholgist, and
have worked with children for the past 37 years. Many had
developmental disorders. I was mainly diagnosing, but doing
some treatment. My 3 year old grand daughter has autism, and
after observing her (before her dx), I came to the conclusion
that she had PDD. I also had the "refrigerator mother" theory
with this dx. Of course, there are TOO many variables, but at
least with this child, the "mother" syndrome seems to make
sense. My grand daughter started working with a habilitator
early June. She was taking the child out of the house, which
concerned me. I was hoping some sort of family intervention
could be done. Now, I am delighted with the progress my
granddaughter has made...and I am convinced that it is BECAUSE
she was taken out of the house, and basically loved by this
lady, that my little darling has made so much progress.
6:08 AM
Blogger Autism Diva said...
Hi Tori's Gma,
The affect that the interaction with parents has on autistic
children is like VERBOTEN to discuss.
Dr. Marian Sigman has studied how parents can interact with
their children to improve the children's communication and
presumable to make the children happier... she taught the
parents to follow the child's lead, to discuss the thing that
the child was showing interest in.
"Oh, Janie, look! That's the prettiest ball you have in your
hand."
as opposed to:
"Point to ball. Janie, point to Ball. Good pointing!"
which is what I have seen in ABA. I haven't seen all forms of
ABA, but the prinicple is to lead, force, etc, the child to do
things that the therapist wants to see the child do or not do.
Love is a huge thing. Kids know when they are being manipulated
and/or not loved. Just because an autistic child doesn't
respond normally doesn't mean that she or he doesn't know when
she is being loved and respected.
11:50 AM
Blogger r.b. said...
I hope to Hector y'all are right!
Nobody brings up Pink Disease (Acrodynia)...the elephant in the
room!
Stuff happens...look at PKU,
Wilson's Disease, Hemachromatosis (the child in the story shows
similar regression)...where inherited susceptibilities cause
slow poisoning and DEATH with phenylalinine, copper, and iron,
respectively. Wilson's Disease was brought up independently by
Dr. Richard Deth at Northwestern, at about the same time I was
wondering about my son's dysgraphia, and found a correlation on
PubMed. In fact, the study suggested that children with
dysgraphia be tested for Wilson's disease. Sixty-five percent
of ADHD kids have dysgraphia, and it was once called Minimal
Brain Damage or Dysfunction and thought to be caused by some
sort of trauma.
But you believe what you want.
6:30 AM
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