epidemic never was

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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