Feb 17 2012

The Autistic Brain at 6 Months

Yet another study showing that clear signs of autism are present as early as six months of age has been published. In this study researchers looked a high-risk children (siblings of children with autism) at 6 months with MRI scanning (specifically diffusion tensor imaging) and then evaluated them clinically at 24 months to see which children met criteria for autism spectrum disorder (ASD). Some of the children also had imaging at 12 months. The imaging was used to look at the development of white matter – the tracks in the brain that contain the axons or pathways of communication.

When compared as groups the 28 infants who went on to develop ASD had significantly decreased white matter development in 12 of 15 brain pathways examined in comparison to the 64 infants who did not develop clinical ASD.  These results are very robust, although I should point out that the children were compared as groups, not individuals. The purpose of this study was to see if there were detectable changes in the brains of children with ASD at 6 months, not necessarily to explore its utility as a diagnostic tool that can be applied to an individual.

Still, this study supports other research providing increasing evidence that ASD begins at least as early as 6 months. It is probable that ASD begins earlier than 6 months, actually, because in order for detectable differences to be present in the brain, development must have been heading down a different trajectory prior to that. These kinds of studies have not looked at children younger than 6 months, and it would be interesting to see how early such changes can be detected. But even without that data, we can conclude the whatever process results in ASD it is active prior to 6 months so that the effects are detectable at 6 months.

This study also supports other research that indicates that autism is partly a disorder of communication within the brain – different parts of the brain have decreased communications with each other. It’s nice when several independent lines of evidence all converge on one cohesive story. With regard to ASD, we have evidence that clinical signs of ASD are present as early as six month and changes in brain anatomy are also present as early as 6 months. Further, there is growing evidence that ASD is the result of a complex set of genetic variations. Autism, in other words, is a genetic disease – which is compatible with detection early in infancy.

This research has several implications. It broadens our understanding of the pathophysiology of ASD – exactly what is happening and how does that manifest with the signs of ASD. Further it offers the potential for earlier and more objective diagnosis of ASD. Laboratory support for a clinical diagnosis is always helpful – again, because it allows for multiple independent lines of evidence, and therefore increases confidence. Early diagnosis is also helpful in identifying children who might benefit from special services.

It’s also possible that research such as this will help us identify specific subtypes of ASD, which may have different causes and different clinical needs. ASD, as the name states, is a spectrum – it’s really a group of similar disorders with similar clinical manifestations. It is likely, however, not one discrete entity. The fact that so many different genetic markers have been identified that are associated with ASD supports this view.

And of course I need to point out that research showing that autism begins prior to 6 months of age rules out any environmental exposure after 6 months as a significant cause. The MMR vaccine (the specific vaccine that Andrew Wakefield tried to link to ASD) is typically given at 12 months of age, and so cannot be a significant cause of ASD. As you can see from the immunization schedule, many vaccines are given after 6 months. Some vaccines, however, are given prior to 6 months, so those intent on blaming autism on vaccines can still point to those earlier injections.

There is no evidence to link any vaccine or vaccines in general to the development of ASD or any neurological disorder. Evidence is converging on the conclusion that ASD is a set of genetic disorders. If history is any guide it’s also true that evidence is not likely to sway members of the anti-vaccine community. But more evidence is always nice. There is always uncertainty in science, and the more we can narrow that uncertainty with better evidence, the better we will be able to make the case for the safety of vaccines.

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13 responses so far

13 Responses to “The Autistic Brain at 6 Months”

  1. PharmD28on 17 Feb 2012 at 11:13 am

    the hardcore anti-vaccine folks are too deranged to care about evidence in general….

    As I was recently told on facebook by a deranged denialist on this subject “why do simply ‘blindly’ accept all of this so called ‘evidence’ that is presented to you?!”

    Any evidence that I cited with this person, including those with very unbiased funding sources, they must ALL be a shill for some nefarious pharmaceutical/governmental interest group. Somehow their filter for what is right and wrong is superior, and I have still yet to figure out why they truly believe this? I mean, it is as if for them being categorically cynical of anything that enjoys scientific consensus is superior and being credulous towards the claims they pick without skepticism or cynisism makes sense????

    The sad thing (and I have said this before in the comments and you have said it countless times) is that their fear mongering noise penetrates non-ideologues and it causes plain folks to make bad decisions.

    Perhaps though once the medical community is able to present a more convincing specific description of autism as far as etiology and such…that the deranged folks will have less and less sway on the credulous minds of “concerned” parents?

    At least I hope that will happen.

  2. ltdiegoon 17 Feb 2012 at 2:41 pm

    I’m not a vaccine hater just curious why no studies have been done to test the safety of the combination of the vaccines administered at the same time. A totally non invasive study of vaccinated and unvaccinated children can be done using QEEGs and looking at hyper and hypo coherence vs norms of age matched autistic and non autistic kids. Who will fund that?

  3. mnestison 17 Feb 2012 at 2:56 pm

    In addition to the support this lends to autism spectrum disorders being biologic/genetic in nature, it is also interesting from a neuroscience perspective. In particular, there is also pretty strong evidence of overall increased brain mass in those with AU spectrum disorders, but this is not apparent at birth or even at 6 months; most have observed this beginning at around 12 months. However, the studies suggest that this increased mass is gray matter; particularly within frontal structures. Many think that problems with neuronal pruning play some role in the development of later symptoms; and this study might suggest that abnormal overgrowth of precentral gray matter, combined with less efficient white matter pathways connecting these structures may be, in some way, related to the lack of gray matter pruning (practically, the structural neurons are not receiving the feedback via white matter pathways that others may be, and thus the genetic pruning mechanisms in place to prune inefficient connections don’t have sufficient structure/function stimuli information to know what to prune). Speculative, but this finding fits existing neuroscience knowledge and is generally fascinating to ponder.

  4. Mlemaon 17 Feb 2012 at 10:31 pm

    “…there is growing evidence that ASD is the result of a complex set of genetic variations.”

    Is there any speculation on what may be causing the increase in these genetic variations?

  5. Woodyon 17 Feb 2012 at 10:53 pm

    There is more than speculation, but if you are curious, google “Geek syndrome” and “autism”. Also check out work on the “Broader Autism Phenotype”. Note that these theories about assortative mating don’t claim to explain all of the increasing autism prevalence (there are other excellent blog posts here that tackle that topic), but they may account for some of it.

  6. Mlemaon 17 Feb 2012 at 11:55 pm

    Interesting.

  7. powerhairon 18 Feb 2012 at 10:04 pm

    Well, my older son (diagnosed with Aspergers at 5) had completely different eye contact patterns (basically refused to) for the first 6 months of his life. His younger brother (by far the most social person in the family!) made excellent eye contact from birth. Watching them now (aged 7 and 5), they clearly think differently.

    So feel free to use this “Mother’s observation” against any anti-vaccine folk, since according to them, the power of the mother instinct trumps all that mere science can offer!

  8. ChrisHon 18 Feb 2012 at 11:29 pm

    Mlema:

    s there any speculation on what may be causing the increase in these genetic variations?

    More genetic research. My oldest son has a very severe genetic heart condition. The first genetic variation was found a few years ago. We are now waiting for the results of his genetics test to see which one of the hundred plus variations that cause the abnormal heart growth (and with that information we will test his siblings to see if it can happen to them).

  9. Mlemaon 18 Feb 2012 at 11:47 pm

    ChrisH,
    I wish you and your family the very best.
    Medical science advances quickly, but never quickly enough for those of us who are coping with the challenges of the now. Believe me, I understand.

  10. etatroon 19 Feb 2012 at 5:23 am

    Maybe we should administer a poll to sort this out …

  11. ChrisHon 19 Feb 2012 at 12:50 pm

    Thank you , Mlema. My son will be having surgery.

    When the genetics expert was discussing his test, which checks only known causes of the abnormal heart muscle growth, she mentioned they could also test for the ones known to cause speech/language issues. I declined, since he is past the time it would have been useful and while he still has some speech issues he can read, write and be understood when he speaks. He is 23 years old, the science and technology was simply not there when he was three years old.

  12. Mlemaon 19 Feb 2012 at 2:21 pm

    ChrisH,
    Your son is fortunate to have a parent who can intelligently conduct him through treatment.
    You are both strong to maintain the course when you’ve had to make your way through uncharted territory. Again, all the best.

  13. RAJon 20 Feb 2012 at 8:28 am

    Autism is a strongly genetically influenced disorder. Recent research from evolutionary biology suggests that autism is not as heritable as has been claimed. In an article published in the SFARI Autism website The results, published online 16 December in Autism, bolster the hypothesis that de novo, or non-inherited, mutations that accumulate in a man’s sperm cells as he ages may increase the risk of autism in his children. The report suggested that advanced paternal age is seen in girls with autism. Girls with older fathers are more than six times as likely as those with younger fathers to show this effect in simplex families.

    Evolutionary biology has demonstrated that all males may generate de novo sperm mutations throughout their lives and the frequency of sperm mutations increases with advancing age. Environmental factor cannot be ruled in understanding the mechanisms underlying de novo sperm mutations in males.

    You can read the article and discussions at :

    http://sfari.org/news-and-opinion/news/2012/effect-of-paternal-age-seen-in-girls-with-autism

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