Autism Cause?

Autism may be a case of too many nerve cells in one specific part of our brains, a meticulous study in the Journal of the American Medical Association reports. While evidence for this idea from MRI studies of the brain has been around for some time, this study actually counted (!) the neurons in the prefrontal cortex (more on that in a bit) from children with autism versus those without.  Surprise!  Kids with autism had about two-thirds more neurons, or nerve cells, in this area than kids who didn't have autism.  As Rick and I opine in the podcast, kudos to those anatomists who performed this tedious work and provided us all with a better window into understanding this often tragic condition.

What exactly did this study do?  It compared the anatomy of specific areas of the prefrontal cortex, so-called dorsolateral and mesolateral areas, abbreviated DL-PFC and M-PFC, in the brains of 7 males who had been diagnosed with autism and 6 who had not.  Assessments included the number of neurons in each of these areas and weight of the brain tissue.  The study found that the DL-PFC of the autistic brains contained 79% more neurons than the controls, while the M-PFC housed 29% more neurons.  The brain weight of those with autism was almost 18% heavier than normalized standards. 

This study substantiates observations that have been made in the past with regard to brain overgrowth and the development of autism.  What's very interesting is the area of the brain that's overgrown:  the prefrontal cortex.  This area functions in what is called 'higher order' tasks, such as complex social, emotional and cognitive perceptions and behaviors, and cognitive development.  Clearly, these are areas that become dysfunctional as autism is manifest.  The study also concludes that since neurons found in these areas of the brain are only developed during fetal life, the roots of autism are laid down during pregnancy and have nothing to do with post-natal exposures.  Yet one more reason to lay to rest that myth related to vaccines and autism.

What I find very provocative about this study is the idea that the prefrontal cortex, the most evolutionarily recent of our brain parts, is overgrown in this condition, not deficient.  Might not that plethora of neurons be put to good use and set to a certain task?  It is well known that we can train our brains and develop new connections among our neurons even at advanced ages.  Can we somehow intervene in the early childhood of someone with autism to harness those extra neurons in some way, perhaps a way that's already chosen by some on the spectrum of autism disorders? Specifically, many persons with autism spectrum disorders are quite brilliant at mathematical reasoning, or music, or whatever.  Would intentional intervention be helpful?

Finally, the idea that during fetal life it's a failure of the proper number of neurons to die is also quite interesting, as suggested by the study authors.  Cell apoptosis, or programmed cell death, is clearly necessary at all stages of life, and advancing our understanding of this process could also potentially result in interventions that may help.

Other topics this week include whether doing a bypass operation helps those with blood vessel blockage inside the head, whether physicians who are financially interested order more cardiac stress tests, both also in JAMA, and liver transplants in those who've abused alcohol in NEJM.  Until next week, y'all live well.

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Autism Cause? — PodBlog | My Autism Site | All About Autism
November 14, 2011 at 12:52 pm

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