Uncommon Sense

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Sunday, January 12, 2003

Autism Epidemic

Reference: I wrote this after a brief discussion at Chaos Manor, which by the way I highly recommend. The essay below incorporates feedback from Chaos Manor's host, Jerry Pournelle, and some of his other correspondents. However, it represents my opinions and interpretations, and I do not speak for anyone else.

Autism. The word conjures up images of Dustin Hoffman, "savants" and other stereotypes. For others, it conjures bitter controversies over potential causes and treatments. The reality, for parents and teachers, can be truly fearsome.

Autism can be a very expensive condition to remediate. Some of the most well-regarded therapies, particularly for the "profoundly" autistic child, involve over 40 hours per week of expert, hands on therapy, directly affecting every aspect of the child's life. As you can imagine, school districts wince when presented with even one profoundly autistic child because of the incredible cost of educating these children.

So what if I were to tell you that we the people are having more autistic children than ever before? The standard theories claim autism is genetic. Today I'll examine evidence that not only is there a non-genetic component, but that the rate of autism is skyrocketing in the United States (or at least, in our most populous state); as one commentator put it, "There's no such thing as a genetic epidemic."

There are currently at least two significant and controversial questions
surrounding autism:

* Is the number of autism cases increasing dramatically?

* Is there a causative relationship between vaccinations and autism?

Today's essay will discuss the first of those questions, and only barely touch
on the second.


The number of cases of autism, real "profound" autism, autism that is hard to
misdiagnose, nearly tripled in California during the 1990s. These are not
"quirky little people who will grow up to be phyics professors"; many of these
children spend their days sitting in one place rocking, or flinging their feces,
or banging their heads into the wall rhythmically. (The "autism spectrum
disorders" associated with higher functioning individuals, such as Asperger Syndrome and PDD-NOS, also increased by huge amounts in that decade.)


Californians, Lord bless 'em, love to track things. California's state
government has more mounds of data on disabilities than any other state.

In 1999, the California Department of Developmental Services released a report
showing a significant increase in the numbers of children referred to the
department for services who were diagnosed with autism. (Autism is nearly always
diagnosed in childhood, usually before school age.)

The short analysis of the 1999 report is this:

(A) The number of cases of autism rose 273 percent among the population served
by the California Regional Center System between 1987 and 1998. By contrast, the
state population rose less than 20 percent over the same time period.

(B) This count includes two categories: "Full Syndrome" autism and "autism,
residual state." The criteria for most psychological disorders, including autism, are specified in the Diagnostics and Standards Manual (DSM), now in its Fourth Edition (DSM-IV). The criteria for autism did not significantly change from
DSM-III to DSM-IV. "Full Syndrome" autism is DSM-IV autism, and pretty much the
description as first identified by Leo Kanner in the 1940s. "Autism, residual state" is a DSM-III diagnostic dropped in DSM-IV, and it refers to those who once met the
criteria for autism but no longer do, but who may retain residual traits. The
report does not disaggregate the categories, which is unfortunate. However, the
diagnostic criteria for autism are substantially similar between DSM-III and
DSM-IV, so this aggregation can reasonably be said to reflect the number of
cases actually occurring even if some are now "cured" or "residual".

The study also showed huge increases (close to 2000 percent) for related
diagnoses"Autism suspected, not diagnosed" and the "autism spectrum disorders" such as Pervasive Developmental Disorders (PDD), PDD-not otherwise specified (PDD-NOS), Asperger's Disorder, Rett's Disorder, and Childhood Disintegrative Disorder. The entire report (including the usual cautions about methods and predictions) can be read at:

CA Report in PDF

Naturally, this result caused a lot of controversy. In particular, the current
usual explanation for autism is that it is solely genetically based, and
certainly there is a whole cluster of disorders including autism that "run in
families." However, that explanation is quite threatened by a 273 percent
increase; it's pretty difficult to credit the California genome as changing that

So, UC Davis set out to vet the 1999 report.

(C) On Oct 17, 2002, the university released the results of an analysis of the
1999 report conducted by the M.I.N.D. institute at UC Davis. The principal
investigator was Dr. Robert Byrd, an experienced pediatric epidemiologist.

(D) The M.I.N.D. report indicates, among several other findings, that "The
observed increase in autism cases cannot be explained by a loosening in the
criteria used to make the diagnosis." It also discounts in-migration as a
statistically significant factor in the increase.

An overview of the M.I.N.D. report results, and links for further information,
are at:

UC Davis Press Release

That result has lent credence to those who suspect a non-genetic agent in the
origin of autism. The most vocal of those folks suspect vaccination as a vector
for the agent, while others suggest dietary changes or pollution. The suggestion
is that the genetic factors "predispose" an individual, and that some of those
predisposed individuals are actually harmed by exposure to some agent (for
example, the thimerosal used to preserve some vaccines).

An older theory held that the MMR (measles, mumps, rubella) vaccine was connected to many cases of autism. However, whatever connection there may be (and I'm not convinced there is one at all), MMR alone cannot account for California's increase, because the MMR vaccine went into wide use in 1971 and the increase begins after 1980.

One interesting anomaly is that, while autism has spiked all over California, it
has particularly spiked in Santa Clara County, aka Silicon Valley. Some theorize
that people with mild tendencies towards "autistic behavior" (or at least, odd
and introverted behavior) become computer geeks, marry geeks like themselves,
and the combination produces autistic children. The concentration of such folks
in San Jose thus lends itself to an increase. This doesn't account for increases
elsewhere in California, but it is one argument that the "genetics-only" faction
clings to in the face of the new data. (Perhaps it would be worth studying other
tech boom areas such as Austin, Boston, Salt Lake and Seattle to help figure out
if there is a recessive gene for geekiness).

BBC's Article

Wired Magazine Article

I will be adding more information on other states as I discover it.