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Archive for November, 2011

By Matt Carey

We live in a plugged-in world. With the internet and smart phones, people never have to be more than a step away from a vast amount of information. I know people who wake up and pretty much immediately check email, Facebook, Twitter, etc.. I’m one of them. Except that I wake up and check for the latest emails from PubMed. I have a number of alerts set up, and it just so turns out that the emails arrive just about as I wake up each day.

The growth in published autism research has been amazing. In 1990 there were 55 abstracts under the topic “autism.” 55 total.
Today, there are days when dozens of abstracts come in on autism, plus more on intellectual disability, developmental disability and other topics I monitor. Most have seen graphs of the growth in the numbers of children diagnosed with autism throughout the 1990’s and 2000’s. I once plotted the number of autism-related research abstracts by year and, after normalizing, found an amazing correlation between the number of abstracts and the number of clients in the California Department of Developmental Disabilities in the autism category. If correlation were causation, we could say that autism research causes autism. More likely is that the same awareness factors are behind much of the increases in diagnoses as well as the number of researchers entering the field.

Below I discuss just a few of the many studies that have recently come out. They are a good cross section of the many areas of autism research being actively pursued today. Mostly, they are the studies which, for one reason or another, caught my eye.

Autism is a broad area of research, and the abstracts reflect that. For example, language delays are common with autism. One question I have personally seen come up is whether a bilingual household would contribute to speech delays. Two recent studies, one from McGill and one from the University of British Columbia indicate that no, bilingual environments do not add to delays. The McGill team wrote “Bilingually-exposed children with ASDs did not experience additional delays in language development”. Perhaps these will help autism parents in multilingual families with the decision about whether to expose their children to more than one language.

Of course, a major focus of autism research involves causation. One in the series of studies using data from Denmark suggests that the risk of autism may be somewhat higher for infants whose amniotic fluid has higher levels of the Monocyte Chemotactic Protein-1 (MCP-1) chemokine.

Low birth weight has been reported to be a risk factor for autism, with a five times higher risk. Some news outlets were confused in their reporting, and cited the risk as higher for preterm births, which was not the focus of the study.

Researchers at Kings College London studied adults diagnosed with autism as children and whether they developed epilepsy. By adulthood, 22% had developed epilepsy, with most the onset was after age 10. Most had generalised tonic–clonic seizures. Thankfully, the majority (28/31) were able to control their seizures with medication, but this goes to show that more work is needed in understanding epilepsy and how to control it.

Personally, I am curious as to whether the 22% prevalence figure will change over time. The characteristics of the autism population are changing with time. California Department of Developmental Services (CDDS) statistics show that the fraction of their clients with epilepsy was going down with time. The adults in the Kings College study were diagnosed in the 1990’s, a time when the CDDS client base had a larger fraction with epilepsy.

A recent study from Stanford looking at adults in Sweden is interesting in that it claims a strong risk for epilepsy with preterm births, in a somewhat tangentially complimentary result to the low birthweight study noted above.

A Harvard study using the Nurse’s Health Study II looked at pregnancy complications and the risk of autism. They found that in general complicated pregnancies increase the risk of autism (about 50% greater risk) and that gestational diabetes in specific was associated with about 75% greater risk.

While studies such as this from the Nurse’s Health Study point to potential prenatal risk factors, developmentally, the first year or two after birth are a time when autistic children often show differences compared to non-autistic peers. For example, in 2003 Eric Courchesne’s group at UCSD discovered that brain overgrowth–rapid growth of the brain during the first years of life–was common in autistic children. A recent study by the Yale Child Center (paper available in full online) found that not only were the brains in autistics on average larger, but the infants were longer and heavier. The increased skeletal growth was evident at 4-5 months, and preceded the head circumference growth which became apparent at 10-11 months.

Autism is diagnosed based on behaviors. This makes diagnosing autism far from a fast process. This is a problem not just for those seeking the diagnosis, but also for researchers looking to expand the number of study subjects available. A study out of Vanderbilt looks at using parent reporting methods as a rapid screening method. In particular they looked at the Social Communication Questionnaire and the Social Responsiveness Scale. While they found that these methods can give rapid results, the slower clinical assessments are still required: “While the rapid phenotyping measures were able to accurately identify a large number of children with ASD, they also frequently failed to differentiate children with ASD from children with other complex neurobehavioral profiles.”

Two more studies from Vanderbilt caught my eye, and these look at family members of developmentally disabled children. One looked at depressive symptoms in mothers following the diagnosis of autism in their children. The study is relatively small, but the authors wrote: “Depressive symptoms immediately following diagnosis were not related to initial global characteristics of child functioning, but were related to reported child problem behaviors and financial barriers at follow-up.” While not specific to autism, another Vanderbilt study considered whether siblings of children with mild intellectual deficits were more likely to work in helping professions or in volunteerism as adults. They found that female siblings were more likely to be in these “helping” professions than male siblings.

Researchers at Harvard and UCLA looked at neurological co-morbidities in autistic individuals. They found that epilepsy, sleep disorders and motor impairments were common.

These are just a few of the studies which have come out in the past couple of weeks. Not every week sees a breakthrough in research in any field. But as long as autism research is supported, every week is a step forward.

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