Nov 07 2013

Early Detection of Autism

Part of the impetus for the fringe belief that vaccines are somehow causally related to the development of autism is that the signs of autism often become apparent at 2-3 years of age, after children have received many of their routine childhood vaccinations. (Average age at diagnosis is 3.1 years.) In an otherwise healthy child, the vaccines might be the only thing the parents can think of that could be a potential cause.

Signs of autism are not clinically noticeable prior to 6 months of age. From about 6-18 months the signs can be detected by careful clinical observation, but may be missed by parents. During this time parents may become slowly aware that their child is not developing as expected, and the creeping suspicion that something is not quite right often culminates in a diagnosis between age 2-3.

The phenomenon of temporal binding may then cause the parent’s memories to shift over time so that the temporal correlation between getting vaccines and signs of autism appearing become closer together. For some parents this can become a very powerful memory – my child was perfectly normal, then he received vaccines and started to show signs of autism.

Meanwhile evidence is mounting that autism spectrum disorder, while heterogeneous, is dominantly the result of genetic predisposition. Changes involving many genes that are involved with brain development have been implicated in autism risk. This does not rule out epigenetic and environmental factors, but the evidence does strongly point to the fact that autism is largely a group of genetic disorders.

If the genetic theory of autism is true then it becomes possible, even probable, that signs of autism will be present even at birth. Although, autism likely represents an alternate developmental pathway for the brain, and so autistic and typical children will become increasingly divergent as their brains develop. The point at which that divergence begins or becomes apparent is not necessarily at birth or in the womb.

Until now the earliest signs of autism could be detected at about 6 months of age, including multiple clinical and MRI studies.  Six months seemed to be the consistent time at which the divergence between autistic and typical brain development becomes apparent.

However, a new study pushes that time back to only 2 months. This is a small study, and should be considered preliminary, but the findings are interesting. Researchers used eye tracking technology to quantify the degree to which infants, mostly in a high risk group for autism, looked at the faces and eyes of people in their environment. One of the hallmark clinical signs of autism is that children are less social and they do not make as much eye contact as typical children.

The researchers found that those children in their study who would later be diagnosed with autism spent less time looking at faces and eyes than children who were not later diagnosed with autism. If this result holds up to replication, it will be the first study to demonstrate clinical signs of autism earlier than six months.

The researchers found no difference prior to two months, and also they found that eye contact in children later diagnosed as autistic decreased steadily from 2 to 6 months of age. This correlates with autism being a divergent pathway of brain development occurring over time.

The researchers were a bit surprised that the autistic and typical children were not already diverging at birth, but finding that the divergence is not apparent until 2 months is still compatible with a genetically determined developmental disorder. They also suggest that their results might indicate a window of treatment opportunity – if high risk children are treated prior to 6 months of age perhaps the potential for a treatment response would be greater. Whether or not brain development in autism can be altered by any currently available treatment remains to be seen.

Given prior research it seemed likely that more sensitive techniques would push the age of earliest detection to prior to 6 months, and now, perhaps, it has. I am curious to find out if 2 months is the true earliest clinical manifestation of autism, or if other or more sensitive techniques will ever push it back to birth, or even in the womb.

It’s possible that the brain simply has not developed enough prior to 2 months of age for any behavior differences, no matter how subtle, to manifest. Brain imaging techniques, however, may still find subtle differences.

This is just one baby step, but it represent the relentless and continued march of the scientific evidence toward the conclusion that autism is a complex set of genetically determined brain development disorders, and away from the hypothesis that vaccines are playing any role.

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9 responses so far

9 Responses to “Early Detection of Autism”

  1. ConspicuousCarlon 07 Nov 2013 at 9:37 am

    “away from the hypothesis that vaccines are playing any role.”

    Get ready to gag yourself with a spoon… When I read about this in some article yesterday, I masochistically went to the comments to see if any cranks had anything to say. One person suggested that it was caused by inherited immunity from the mother’s vaccination. I jab you not.

  2. Gallenodon 07 Nov 2013 at 12:21 pm

    “Meanwhile evidence is mounting that autism spectrum disorder, while heterogeneous, is dominantly the result of genetic predisposition.”

    That statement generated a question for me based on something I think I’ve heard annecdotally about there being more boys diagnosed with autism than girls. Is that true and, if so, what is the ratio of boys to girls diagnosed as having something from within the autism spectrum?

    And, if there are a significanlty larger percentage of boys, does that mean there’s some likelihood that whatever genetic predisposition there may be towards autism might be based on some characteristic of the Y chromosome itself?

    I suppose I could go look for information on the Internet, but I consider most of the people I see posting here as more reliable sources, so I thought I’d ask.

    Thanks.

    Dale

  3. Todd W.on 07 Nov 2013 at 12:57 pm

    @ConspicuousCarl

    Yeah, the idea that the mother’s vaccinations are what caused the problem popped up a while ago. As time passes, that idea will become more and more difficult to test, unless the population of completely unvaccinated individuals increases. Most of the mothers whose children are being diagnosed now have probably had some vaccinations when they were a child. Their parents would have had fewer, and their grandparents would have had only a couple (or none) before they had kids. But I’ve heard that argument before to explain why, for example, Kim Stagliano’s (of Age of Autism) third daughter, who is completely unvaccinated, is still autistic.

    @Dale

    Boys, IIRC, have a roughly 4-times greater risk of autism than girls. But I seem to recall that 4-1 ratio not holding up across all variations of the spectrum. There is also some question as to whether differences in how genders are treated may play a role in that discrepancy. In other words, there might actually be more girls who have an ASD than are diagnosed because of how other people behave toward or view girls.

  4. Gallenodon 07 Nov 2013 at 2:23 pm

    @Todd:

    Thank you, that’s precisely why I asked the question here instead of trying to wade through the bog that constitutes the bulk of Internet-based information about autism. :)

  5. steve12on 07 Nov 2013 at 2:45 pm

    How long before we see accusations that Dr. Pr-offit & Big Pharma have built time travel technology into vaccines?

  6. Davdoodleson 08 Nov 2013 at 12:32 am

    “One person suggested that it was caused by inherited immunity from the mother’s vaccination.”

    That’s no surprise. I’m sure its the very first thing they thought of which achieves their real aim: To preserve their wrong-headed notion that vaccines are to blame, no matter what.

    So, just special-plead, shift the goalposts, and the crazy carousel lurches off again.

    Cue the creepy Wurlitzer music.
    .

  7. Brad Smithon 08 Nov 2013 at 1:07 am

    @steve12: Please don’t give them ideas…

  8. zorrobanditoon 18 Nov 2013 at 5:46 pm

    As for more boys being impacted by ASD than girls, I would propose the hypothesis that because females in general in our species are more relationship-oriented than males, the marginal autistics in the female population might be better prepared to minimize or deal with the condition than the males, and thus escape diagnosis.

  9. kwillcoxon 16 Jun 2014 at 3:52 pm

    Children with autism are two to three times more likely than other children to have been exposed to car exhaust, smog, and other air pollutants during their earliest days, according to a new study.

    That new research adds to a mounting body of evidence that shows a link between early-life exposure to pollution and autism spectrum disorders. There is also a link between autism and living downwind from coal power plants.

    In research published in the journal Pediatrics, scientists studied the rates of developmental disorders like autism among nearly 97,000 children born in Denmark between 1997 and 2003. The children’s mothers answered questions about infections they might have had during pregnancy — colds, sinus infections and urinary tract infections, among others. They also reported whether they’d suffered from the flu or had fevers that lasted more than seven days before they gave birth.

    When the researchers compared the mothers’ answers to the registry of developmental disorders, they found that moms who fought the flu while expecting had children with double the risk of being diagnosed with autism before their third birthday. Mothers who endured flu-based fevers for seven days or more had triple the likelihood of having kids with autism, and those mothers also had a 60% greater chance of having a child diagnosed with developmental difficulties falling into the more expansive category of autism spectrum disorders (ASD).

    As usual, the author of this blog combines his snarky and rude comments with a glaring lack of scientific knowledge. I am just glad he is not treating me or my family.

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