Neuronal Disorganization in Autism

Study finds abnormal cellular layering within the brains of children with autism, pointing to inappropriate development prenatally.  

By | March 27, 2014

WIKIMEDIA, JOHN A. BEALAccording to survey data from the Centers for Disease Control and Prevention released today (March 27), one in 68 eight-year-olds in the U.S. has an autism spectrum disorder. That’s nearly double what was estimated a decade ago. It’s not entirely clear why, but researchers are getting closer and closer to understanding the neural roots of autism. In a study published today in the New England Journal of Medicine, researchers from the University of California, San Diego, and their colleagues examined the brains of 22 children who died. The team found that kids who had autism were far more likely to have had disorganized patches of cortical neurons than those who didn’t have the disorder.

Given that the cortex takes shape prenatally, the researchers interpreted their findings as a sign that the brain changes leading to autism begin in utero. “If this new report of disorganized architecture in the brains of some children with autism is replicated, we can presume this reflects a process occurring long before birth,” Thomas Insel, the director of National Institute of Mental Health, which funded the research, said in a statement. “This reinforces the importance of early identification and intervention.”

The cortex is normally ordered in distinct layers of neurons, but 91 percent of the autistic children had small regions in their brains where genetic markers of these layers were absent. In comparison, just 9 percent of the kids without autism had these regions of disorganization. The patches were about five to seven millimeters in length and spanned several layers of cortical neurons. “The most surprising finding was the similar early developmental pathology across nearly all of the autistic brains, especially given the diversity of symptoms in patients with autism,” coauthor Ed Lein of the Allen Institute for Brain Science in Seattle said in a press release.

Stanley Nelson, a geneticist at UCLA, told NPR that the results add to the evidence that autism begins before birth. “The overwhelming set of data is that the problems are existing during brain development, probably as an embryo or fetus,” he said.

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Avatar of: Neurona

Neurona

Posts: 34

March 28, 2014

So if autism is a prenatal disease process, then Jenny McCarthy et al. of the anti-vaccination crowd are barking up the wrong tree, yes?

Avatar of: Doug Easton

Doug Easton

Posts: 13

March 28, 2014

It is likely that there is something going on in the maternal-fetal environment which is responsible. It reminds me of Fetal Alcohol Syndrome which also has very consistent pathology. Someone needs to do a retrospective analysis of events during pregnancy that might be associated with the disease. I am not certain but I believe some such studies have been done. However, now that a a specific pattern of pathological changes a has been described for the disease, there might be clues as to the type of prenatal insult that might cause such changes.

Avatar of: cagperez

cagperez

Posts: 1

March 28, 2014

This is an interesting study that shows in post-mortem Autistic brain tissue , the presence of “patches” in the brain that maybe related to developmental defects. It is known that effects in genes and/or signaling pathways during brain development may have a direct implication in brain disorders in the adulthood. In other words, if the brain does not develop properly, the consequences can increase the predisposition of an individual to develop any of those disorders in the adult. It is not clear to me though, how long did it take them to fix those brains to exclude any degradation of the tissue or if those “patches” are clearly associated with a neurodevelopment defect. In any case, would be nice to do a gene screening in some “non-fix” brain tissue to relate those “patches” with any kind of difference in the expression of any of the genes that it is known are relevant for brain development, in particular cortical development. 

Avatar of: Nemo

Nemo

Posts: 3

March 28, 2014

The removal of the BRCA  gene from mice causes such changes. Could the cause of breast cancer be what protects children from autism?

Has anyone correlated BRCA  and incidence of autism?

http://www.ncbi.nlm.nih.gov/pubmed/19403657

Avatar of: PastToTheFuture

PastToTheFuture

Posts: 34

March 29, 2014

The comments here are fascinating.

My concern is that many human biological problems are caused by de novo mutations. I would not say that this is the case here as the frequency of autism seems too high for that to be the cause. I would be more inclined to go with Doug's posit that it is something in the maternal-fetal environment. If it is de novo mutations though, we are in trouble. ... I guess if we are at 1 in 6, we are in a bit of trouble anyway.

.... So how can this "defect" give rise to enhanced concentration or some of the other occasional "positive" features of autism.

Avatar of: Hugh-F-61

Hugh-F-61

Posts: 41

April 18, 2014

The patches look like scars of viral (or bacterial) plaques or local autoimmune destruction; spots where a clump of cells die and are removed. Were they killed or did they fail to develop properly in the first place? Presumably the variability in symptoms depends on just what that group of cells should have been connected to and doing, and how many lesions there are, and how big.

The figure shows the outer layer of cell (purpleish) being reduced and wavy, as if there is physical disruption in the layers below. This argues against the lack of RNA being due to post-mortem decay, and fits with structural disruption during development..

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