Study Finds That Brains With Autism Fail to Trim Synapses

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Study Finds That Brains With Autism Fail to Trim Synapses as They Develop

By PAM BELLUCKAUG. 21, 2014

http://www.nytimes.com/2014/08/22/healt ... pe=article

As a baby?s brain develops, there is an explosion of synapses, the connections that allow neurons to send and receive signals. But during childhood and adolescence, the brain needs to start pruning those synapses, limiting their number so different brain areas can develop specific functions and are not overloaded with stimuli.

Now a new study suggests that in children with autism, something in the process goes awry, leaving an oversupply of synapses in at least some parts of the brain.

The finding provides clues to how autism develops from childhood on, and may help explain some symptoms like oversensitivity to noise or social experiences, as well as why many people with autism also have epileptic seizures.

It could also help scientists in the search for treatments, if they can develop safe therapies to fix the system the brain uses to clear extra synapses.

The study, published Thursday in the journal Neuron, involved tissue from the brains of children and adolescents who had died from ages 2 to 20. About half had autism; the others did not.

check the link above for the whole story

I have seen it theorized that the above is related to overly-accelerated brain growth in people up to the age of 2--that results in faulty neuronal connections.

But would this be the cause, one of the causes or a symptom? That process isn't supposed to happen until adolescence but there are diagnosable symptoms from early childhood.

I saw a documentary on TV almost 20 years ago about how the mind of an infant develops and it talked a lot about how synapses are formed and then pruned during infancy and the toddler years.
This current study seems to imply that the pruning happens later.
Maybe it's an ongoing thing throughout childhood.

I've not read the study, but my guess is it's supposed to go on periodically in various parts of the brain from toddlerhood on. And it make so much sense to me that I suspect the theory had been bandied about for quite a long time and that this is just first evidence.

Genetically all these things are to do with timing -- a gene is supposed to switch on or off in response to other signals -- and it's not an ongoing process, which makes any kind of cure difficult. Other genetic diseases that have to do with processes that happen all the time -- like metabolic processes -- if you can figure out how to do the gene transfer, you might be able to make something happen. But if you screw with developmental timing who knows what you're doing. It'd mean you would have to find and replace the defective gene in utero or in infancy, I suppose. And considering that this is a matter of degree, not kind -- very mild Aspergers can be a real asset, less mild a serious liability...well, they're gonna go through a lot of mice.

Yep, thats my take on it. The over-connected brains and due to lack of synaptic pruning has long been considered a possible cause, but this study seems to A. demonstrate this, and B. correlate it with a protein called mTOR being 'overactive'.
Extrapolating a lot here, but that could kindof explain why there is no obvious singular cause of Autism - if this protein was the cause, then elevation of this protein could arise due to a number of different unrelated things.
Interesting. I wonder if over-connection in some areas accords strengths in those areas, or if it's more akin to a room where everyone is yacking and you can't get anything done?

Interesting topic. This a little different than some other articles I read on similar topic. Thanks for sharing.

Synapses are pruned throughout a person's life, the rate of pruning merely changes. Information is streamlined and unused neural associations are cut off in favor of more regular patterns and associations.

That makes sense.
This theory could explain a lot of the features of autism, such as savant syndrome, special interests, sensory processing, etc.

I think the study is fascinating, but I find it disappointing that the main goal of the study is to find a cure in the form of finding a way to return pruning of synapses to normal in autistic people, instead of using the study as a way of understanding and helping people without messing with the way their brains work.

When I saw that documentary years ago about how synapses were pruned in infant brains, I wondered if that was what was wrong with my brain, that maybe my synapses didn't get pruned properly.
I also wondered if that was the cause of autism, though I didn't know much about autism at the time.

Well, most people I know have WAY too much pruning.

I read this article myself a few days ago. In plain English, it says that the brains of autistic people develop differently from those of normal people and are overloaded with information they can't disregard or prioritize. When all the parts of your brain are constantly talking to each other, all you have is noise. I've heard autistic people describe the feeling of being in a crowded room with many people talking to them at once, and I guess that's exactly what we're dealing with in our minds. Very interesting.

You just described the inside of my head.

Made me LOL too.

I could have told them Valium makes autism a lot better.

CNS depressant (especially anti-epileptic) = less brain excitability, which = greater functioning

My brain just eats Valium up. Booze too.

Tall-P - This was quite an interesting article. Thanks for sharing.

Funny. And true.


This describes my experiences exactly. Until recently, I figured everyone felt this same way.