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Autism Still a Mystery

Tornado Science, Facts and History

April is autism awareness month, when doctors make us aware of how little they know about autism. They can't define it, can't say what causes it, and can't even determine if the rates are truly climbing.

They are, however, rather clear on what doesn't cause autism. And that's vaccines.

It's a simple message — vaccines don't cause autism — yet one that many people either don't hear or don't believe, for the mainstream media present the theorized vaccine link as an ongoing, open-ended debate.

There are many voices advocating the vaccine link, and they can be passionate, intelligent, wrenching and sincere. But this doesn't mean they are correct.

Politics and numbers

Senator John McCain clouded the picture at a Texas town hall meeting in February, saying, "It's indisputable that [autism] is on the rise amongst children... and there's strong evidence that indicates that it's got to do with a preservative in vaccines."

Well, no and no. Rising rates are still in the realm of speculation, and there is a preponderance of evidence demonstrating autism has nothing to do with vaccines, let alone vaccine preservatives.

An often-cited figure is 1 in 150 children diagnosed with autism. Sounds frightening, but it's wrong. This is the estimated rate of autism spectrum disorders (ASD), which includes autism along with milder psychological conditions affecting social and behavior skills. Many people with ASD lead productive lives, often as scientists, with anti-social behaviors once simply called eccentric.

The prevalence of full-blown autism is estimated at about 1 in 1,000, according to the Centers for Disease Control and Prevention. Autism rates have "climbed" with the broadened definition of ASD, better diagnosis to differentiate autism from other mental disorders, and the establishment of CDC's Autism and Developmental Disabilities Monitoring Network, which started counting cases in 2000. Whether absolute rates have climbed as a result of environmental factors is debated.

As for the vaccine preservative, the mercury-base chemical called thimerosal was removed from almost all vaccines as a precaution years ago, but ASD rates have not declined.

Passions and celebrities

Parents of autistic children are not convinced. Some are suing vaccine manufacturers and are warning other parents to be aware of the dangers of vaccination.

Actress Jenny McCarthy has an autistic child. Her celebrity has enabled her to promote the vaccine-autism link on Oprah, Larry King Live and other popular programs. She also authored "Louder than Words: A Mother's Journey in Healing Autism," which, although flawed scientifically, is arguably the best book written about autism by a former Playboy bunny.

One cannot deny that these parents know their children better than doctors do, and that their children exhibited autistic behavior directly after vaccination. The intense period of childhood vaccines, however, overlaps the time when autism, present at birth, manifests itself.

In fact, researchers now are concentrating on identifying autism as early as possible. The cause remains unknown, but everything points to a birth disorder: Upwards of 90 percent of ASD cases have a hereditary link, according to studies summarized in the journal Molecular Psychiatry last year, and often autism is associated with genetic diseases that manifest themselves early, such as phenylketonuria (PKU).

What the herd hears

All drugs carry risk. If the CDC downplays the vaccination risk, this is because we cannot afford to have parents opting out of vaccination programs.

For vaccinations to work, a society needs most of its people vaccinated to create herd immunity. The MMR vaccine, for example, is only about 90 percent effective, but if everyone is vaccinated, then the risk that measles, mumps or rubella can spread among a population is extremely low.

Some U.S. communities have dangerously low vaccination rates, largely a result of religious exceptions and fear of autism. The last big measles outbreak was in 2005, when an American girl who wasn't inoculated visited Romania and brought the disease home to Indiana, spreading it at a religious gathering to 34 others, nearly all of whom were also not inoculated.

Measles is not a cute disease that makes your face break out in dots. It kills a half-million children each year and it is a major cause of deafness. Many older deaf adults today, born before widespread use of the MMR vaccine, lost their hearing in early childhood from a bout of measles, mumps or rubella (German measles).

You could opt out and let everyone else's immunity protect your child. But in this shrinking world, that's a dangerous decision. Polio has shown up in New York City; deadly viruses are just a plane ride away. In fact, a measles outbreak in Pima County, Ariz., that began in February had nine people, including four children as of April 1. Officials said they're concerned it could spread throughout the state.

Also dangerous is the promotion of the theorized vaccine-autism link, for it only hinders our ability to find the real cause of autism.

Christopher Wanjek is the author of the books “Bad Medicine” and “Food At Work.” Got a question about Bad Medicine? Email Wanjek. If it’s really bad, he just might answer it in a future column. Bad Medicine appears each Tuesday on LiveScience.