If you watch for autism related news stories you likely have seen multiple stories on a paper out Friday in the American Journal of Psychiatry: Differences in White Matter Fiber Tract Development Present From 6 to 24 Months in Infants With Autism (full paper available online). The researchers studied brain structure in children and compared those who went on to be diagnosed with autism to those who did not. They found differences in white matter between the two groups. In particular fiber tracks were different.
Here’s figure 1 ( click to enlarge ) from the paper to give you an idea of what they mean by fiber tracks. Check the brain cartoons on the right. Then check the actual data in the graphs. These are “significantly different” trajectories for these measurements. They are not clear differences that could lead to a diagnostic tool.
Here is the abstract:
If the idea of differences in fiber tracks seems somewhat famiiliar, last year Eric Courchesne at UCSD reported at IMFAR about
At the press conference David Amaral mentioned similar work at the IMFAR press conference last year.
At 51:20 in the video above, Prof. Amaral speaks on the work that precocious brain growth at 4-6 months of age in infants and is most prominently present in children with regression.
“..despite the fact that the regression, the behavioral regression, takes place at 18 months or 24 months, the brain changes actually started taking place at 4 to 6 months. So it actually casts a doubt on the idea that a vaccine, the MMR vaccine for example that’s taken at 12 to 18 months, would be actually the precipitating factor because things were starting much much earlier than that.”
The talk that Prof. Amaral was speaking about was Total Cerebral Volume Is Associated with Onset Status In Preschool Age Children with Autism.
C. W. Nordahl1, A. Lee1, M. D. Shen1, T. J. Simon1, S. J. Rogers1, S. Ozonoff2 and D. G. Amaral1, (1)Psychiatry and Behavioral Sciences, UC Davis M.I.N.D. Institute, Sacramento, CA, (2)Psychiatry and Behavioral Sciences, M.I.N.D. Institute, UC Davis, Sacramento, CA
The idea that autism, even regressive autism, has signs as early as 6 months is challenging to some groups on two levels. First the idea that autism involves physical differences in the brain. Second that these differences are present well before regression, or well before vaccines which are sometimes proposed as precipitating events.
The study itself has limitations, one being generalizability. It makes a lot of sense to monitor siblings of autistics since the recurrence risk is high and the chances of collecting data on autistics is higher than in the general populaiton. However, this leaves us with the question: are the types of autism found in siblings (familial autism) representative of all forms of autism?