Maternal age affects autism development?

10 Feb

A new study that looked at a large birth cohort (almost 5 million participants) over a 10 year period has announced that maternal age is an indicator of developing autism with an approximately 50% higher risk for a woman in her forties than a woman in her twenties.

The researchers looked at the records for all births in California between Jan 1990 and Dec 1999. Cases of autism were identified from this cohort using the records from the Early Start Report (ESR) for children under three, and the Client Development and Evaluation Report (CDER) for children over three.

A diagnosis of autism was defined as either positive for Developmental Disabilities on the ESR, or an autism level of one a CDER record/ICD code for autistic disorder. After excluding children from multiple births and those with missing data there were 12,159 cases and 4,935,776 controls.

Thats an interesting autism rate of 0.2% which might indicate more than maternal age that ESR or CDER is not that good at catching autism diagnoses as its a very low rate compared to the US national 1%.

This paper also lacks strength when looking at confounding factors – admittedly a tricky proposition as we don’t know what causes autism – but it may be of interest that the confounding factors that they _did_ account for were mainly ethnocentric i.e. race, gender etc and that they found that yep – whites were mainly very well represented. It seems very likely therefore that of possibly more interest that maternal age might be that not enough efforts are being made by local authorities to go into non-white enclaves.

9 Responses to “Maternal age affects autism development?”

  1. farmwifetwo February 10, 2010 at 11:48 #

    Considering neither parental age in our house qualifies for either study…. we’ll ignore it. The one I read said it may contribute 5% of all autism cases… WOW!!! NOT!!!

    • Sullivan February 10, 2010 at 13:16 #

      People who are looking for a “real” increase in autism will ignore one possible cause. People supposedly looking for the causes of autism will ignore one cause.

      The basic response for any cause of autism that isn’t vaccines–genetic or environmental–ignore it.

      Good thing science isn’t dictated by a vote.

  2. passionlessDrone February 10, 2010 at 14:29 #

    Hi Kev –

    Thanks for posting this, I’d seen it somewhere else previously but hadn’t had time to comment. This study seems to make sense from a mechanism point of view, and conforms generally with other similar studies.

    This group seems to have been slicing the California data a lot lately. Even with the problems with that data, I’m of the mind that we can learn something from it. What might be interesting, for instance, would be to view an overlay map of the autism cluster maps posted here a while ago on top of an average age of mothers map. I’d imagine we’d see some small overlaps.

    Has anyone read the entire paper yet? My real email address has asked for a copy. A chunk of these children were born before the expansion of the DSM; it might be interesting to evaluate the rates of autism on their ESRs (i.e., before DSM expansion), versus rates of autism (as opposed to spectrumy disorders) after expansion of DSM, if such detailed information was available.

    The rate does seem very low; perhaps there are other diagnostic tools that could be evaluated. Our data quality is a big problem. Or, alternatively, there is the chance that children born in the nineties simply had less behaviors consistent with autism than children born in the following decade.

    – pD

  3. livsparents February 10, 2010 at 17:55 #

    You wonder if the same socio-economic factors surrounding the geographic’hotspots’ could have paralells with this. The more affluent and more educated are more likely to put off having children until later and also will likely have higher income and better access to services. I bet we see more than just a small overlap…

  4. Leila February 10, 2010 at 19:20 #

    FW2, it’s not always about YOU, you know? This information is very important in the search for causes of autism, and very important for people who may want to be aware of the risk of having autistic offspring if they decide to have children later in life.

    It makes sense that maternal and paternal age are factors because that is also a cause for other congenital problems.

    • Sullivan February 10, 2010 at 19:21 #


      well said. If there were a paper stating that 5% of autism in children could be linked to vaccines, my guess is that farmwifetwo would have a very different take on the importance of the finding.

  5. Jeff Gitchel February 10, 2010 at 20:46 #

    Perhaps older parents tend to be better parents 😉

    So far, the MIND Institute – dedicated, as they themselves say, to finding a cure for autism – has shown that older, richer parents who live in big cities, usually near autism research centers, have more children who are autistic.

    Lucky for their bottom line that it wasn’t poor, young parents in rural America.

    How fortunate for them and their sponsor, Autism Speaks.

    I would have thought they’d have found an alarming tendancy for autistic parents to have autistic children, except autistic adults don’t seem to exist in AS’s worldview, they tend not to be big contributors to AS, and – most of all – that would tend to show a strong genetic link. The MIND Institute has gone on record as lamenting the amount of money going toward genetic research as opposed to environmental research.

    Better to find some sort of environmental connection with old-lady mothers. Lilac perfume, perhaps?

    Sorry for the tone, but I’m positively dismayed with the number of stories springing up from professional news organizations citing this research as showing older parents as a “cause” for autism.

  6. Joseph February 10, 2010 at 22:03 #

    Yes, maternal age correlates with socio-economic status. There’s some data from Scotland on this, but the site appears to be dead as I’m writing this.

  7. Lori February 13, 2010 at 02:37 #

    As the research presents evidence that maternal age maybe a contributing factor for autism, I agree with Kev that the study included a small sample. The geographics of the study comprising mostly one ethnic and socioecominic group located in a certain area does not make the study valid.

    Maternal age has been a contributing factor other disorders such as Down’s Syndrome, yet is has not been contributing factor to such things as ADHD. More extensive research studies are needed.

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