WSJ Health Blog: Mercury in Vaccines Not To Blame for Autism Increase

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January 7, 2008

Mercury in Vaccines Not To Blame for Autism Increase Posted by Shirley S.

Wang

Mercury-based preservatives in vaccines given to children aren't a primary

cause for the increase in diagnosed cases of autism, reiterates a study

published <http://archpsyc.ama-assn.org/cgi/content/full/65/1/19> today in

the Archives of General Psychiatry.

The theory that vaccinations with

thimerosal<http://www.cdc.gov/od/science/iso/concerns/thimerosal_faqs_thimerosal\

..htm>cause

autism has been largely dismissed by the scientific community for

years, yet parents decline to have their children vaccinated because of the

fear.

This study examined children diagnosed with autism in the state of

California between 1995 and 2007. Thimerosal levels in vaccinations were

drastically reduced around 2001, so the authors reasoned that if thimerosal

were causing autism, the prevalence of autism should begin declining in the

years after that point.

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Instead, the data showed that the number of children diagnosed with autism

increased steadily (click on the chart to enlarge it). For 3-year-olds, the

prevalence increased from 0.3 children per 1000 live births in 1993

(reported in 1996) to 1.3 for children per 1000 births in 2003 (reported in

2006).

" The data seem to show that kids are getting diagnosed at younger ages over

time, which would be a likely result of increased efforts to make the signs

and symptoms of autism aware to the public and to physicians, " study author

Schechter, a medical officer with the immunization branch of the

California Department of Health told the Health Blog. " Whether the increase

is all disease, all recognition, or a mixture of both, I don't know. "

The database didn't keep track of other autism-spectrum

disorders<http://www.nimh.nih.gov/health/publications/autism/complete-publicatio\

n.shtml>such

as Asperger syndrome. The study also didn't examine the measles

vaccine, which was also suspected of causing autism and

deemed<http://www.cdc.gov/od/science/iso/concerns/mmr_autism_factsheet.htm>unfou\

nded

by the medical field.

Why the cases of diagnosed autism are on the rise continues to be a puzzle.

While vaccinations are likely not the culprit, it is does seem plausible

that some environmental factors play a role in the increasing rate of

diagnosis and investigation on this topic needs to continue, the authors

write.

*Chart courtesy Archives of General Psychiatry*