Anti-vaccinationists frequently a quote the recent (the
last 10 - 15 years) increases in autism as evidence that vaccines cause autism. Since virtually all good science contradicts
this idea, it seems there must be another explanation for this apparent
increase. One possible explanation is a change
in diagnosis - children who are now diagnosed as autistic would have been
diagnosed with a different condition 20 years ago. Anti-vaccinationists ask, “where are the hidden
hordes?” – the adult autistics who were not diagnosed autistic as
children. Because, if increases in
autism are merely a change of diagnosis, then there must be numerous adult
autistics who were not diagnosed as such as children.
Professor Dorothy Bishop of the University of
Oxford, led a recent study to examine this question. The study was published this month in the Journal of Developmental Medicine &
Child Neurology, and its conclusion was indeed to suggest that many
children who would now be diagnosed as having autism, were in the 1980s and
1990s diagnosed with severe language disorders instead.
From the abstract
we can see that Bishop looked at 38 subjects (aged 15 to 31), who had, as
children, been diagnosed as having developmental language disorder, rather than
autism. She then applied to them, modern
tests for diagnosing autism at age 4 to 5 years – tests that involved interviewing
both the subjects and their parents. The
result was that one third of the subjects met the modern criteria for autism. The interviews with the parents were
especially revealing: the subjects’ parents recalled what we would now regard
as autistic symptoms appearing in their children when they were very young. The conclusion is that much of the recent rise
of autism could be due to a change in the diagnostic criteria.
The result is consistent with this study
in Pediatrics from 2006 that showed the growing autism diagnoses from 1994
to 2003 were associated with corresponding declines in other diagnostic
categories.
Of course the study needs replicating with a much
larger number of subjects than 38, before any firm conclusions can be
drawn. But the study’s tentative
conclusion is consistent with the total lack of evidence that autism is caused
by vaccines. To be sure, the
anti-vaccine crowd would have been quick to publicize this study if the results
had been negative, but now they will probably ignore the study, or criticize
the independence of the study’s authors. That is their normal tactic when faced with studies they don’t like but
have no evidence to refute. But what
they won’t have are valid criticisms of the actual study, or studies of their
own that show there was, in fact, no change in diagnostic criteria.
It would be nice if CNN and Larry King would now have
Professor Bishop on to explain her studies to the public, and undo some of the
misinformation they recently helped put out. But, again, we can be sure this won’t happen. They get higher ratings showing the idiotic
views of “Professor” Jenny McCarthy.
References
Abstract: Autism
and diagnostic substitution: evidence from a study of adults with a history of
developmental language disorder
University of Oxford: Rise in
autism related to changes in diagnosis
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