Post by Lawrence Gordon on Oct 31, 2011 14:41:29 GMT
A Report from Al Jazeera
Not long ago, autism was among the rarest of disorders, afflicting only one child in every 2,000-5,000.
This changed dramatically with the publication in 1994 of DSM-IV (the manual of psychiatric diagnosis most widely used around the world). Soon, rates exploded to about one in every 100. And a large study in South Korea recently reported a further jump to 1 in 38 - an astounding three per cent of the general population was labelled "autistic".
What is causing this epidemic and where are we headed?
The natural reaction to any plague is panic. Parents are now fearful that every delay in speech or socialisation presages autism. Childless couples decide to avoid having kids. Parents with autistic children are desolate and desperate to determine its cause.
The British physician Andrew Wakefield's vaccine theory became wildly popular among parents, many of whom began to withhold vaccination (thus subjecting their own and other children to the risk of entirely preventable, and sometimes serious, illnesses).
Vaccination seemed a plausible cause because of the fortuitous correlation between getting shots and the onset of symptoms. Wakefield's work has now been thoroughly discredited as incorrect and dishonest science. But fear of autism is so great, and the reactions to it so irrational, that in some circles Wakefield continues to be revered as a prophet.
Other factors must be behind the sharp rise in the diagnosis. Before DSM-IV, autism was among the most narrowly and clearly defined of disorders. Symptoms had to begin before age three and comprised a striking and unmistakable combination of severe language deficits, inability to form social relationships, and a preoccupation with a very narrow set of stereotyped behaviours.
In preparing DSM-IV, we decided to add a new category describing a milder (and therefore much more difficult to define and distinguish) form of autism, called Asperger syndrome. This seemed necessary because some children presented with more or less normal language development, but with grave social and behavioural difficulties. the condition was still quite rare, but we knew that Asperger's would likely triple the rate of autistic disorders to about one in 500-1,000 - but this doesn't explain the new rate of one in 38.
A second possible explanation for the explosion in autism is that previously missed cases are now being more accurately diagnosed. This is probably a factor, but again only a minor one.
Perhaps, then, an environmental toxin is causing an epidemic outbreak of autism. This has been the most popular theory, but it, too, is a small factor, at best. There has been no sudden environmental change since 1994 to account for an explosion in rates. This doesn't entirely disprove an environmental vector, but it does make the odds quite remote - especially since there is a far more plausible explanation
The autism "epidemic" is set to spread further starting in May 2013, when the next revision of the diagnostic manual (DSM 5) will be published. The DSM 5 definition of an "autistic spectrum" will cast an even wider net, capturing many people now considered to be normal or to have another disorder. Their symptoms will not have changed - just the label.
Not long ago, autism was among the rarest of disorders, afflicting only one child in every 2,000-5,000.
This changed dramatically with the publication in 1994 of DSM-IV (the manual of psychiatric diagnosis most widely used around the world). Soon, rates exploded to about one in every 100. And a large study in South Korea recently reported a further jump to 1 in 38 - an astounding three per cent of the general population was labelled "autistic".
What is causing this epidemic and where are we headed?
The natural reaction to any plague is panic. Parents are now fearful that every delay in speech or socialisation presages autism. Childless couples decide to avoid having kids. Parents with autistic children are desolate and desperate to determine its cause.
The British physician Andrew Wakefield's vaccine theory became wildly popular among parents, many of whom began to withhold vaccination (thus subjecting their own and other children to the risk of entirely preventable, and sometimes serious, illnesses).
Vaccination seemed a plausible cause because of the fortuitous correlation between getting shots and the onset of symptoms. Wakefield's work has now been thoroughly discredited as incorrect and dishonest science. But fear of autism is so great, and the reactions to it so irrational, that in some circles Wakefield continues to be revered as a prophet.
Other factors must be behind the sharp rise in the diagnosis. Before DSM-IV, autism was among the most narrowly and clearly defined of disorders. Symptoms had to begin before age three and comprised a striking and unmistakable combination of severe language deficits, inability to form social relationships, and a preoccupation with a very narrow set of stereotyped behaviours.
In preparing DSM-IV, we decided to add a new category describing a milder (and therefore much more difficult to define and distinguish) form of autism, called Asperger syndrome. This seemed necessary because some children presented with more or less normal language development, but with grave social and behavioural difficulties. the condition was still quite rare, but we knew that Asperger's would likely triple the rate of autistic disorders to about one in 500-1,000 - but this doesn't explain the new rate of one in 38.
A second possible explanation for the explosion in autism is that previously missed cases are now being more accurately diagnosed. This is probably a factor, but again only a minor one.
Perhaps, then, an environmental toxin is causing an epidemic outbreak of autism. This has been the most popular theory, but it, too, is a small factor, at best. There has been no sudden environmental change since 1994 to account for an explosion in rates. This doesn't entirely disprove an environmental vector, but it does make the odds quite remote - especially since there is a far more plausible explanation
The autism "epidemic" is set to spread further starting in May 2013, when the next revision of the diagnostic manual (DSM 5) will be published. The DSM 5 definition of an "autistic spectrum" will cast an even wider net, capturing many people now considered to be normal or to have another disorder. Their symptoms will not have changed - just the label.