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Study Offers Clues To How Autism Develops


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A new study finds that children with autism have extra synapses, which can affect how the brain functions. Synapses connect neurons, like the one pictured, to each other. (Guomei Tang, PhD and Mark S. Sonders, PhD/Columbia University Medical Center)

A new study finds that children with autism have extra synapses, which can affect how the brain functions. Synapses connect neurons, like the one pictured, to each other. (Guomei Tang, PhD and Mark S. Sonders, PhD/Columbia University Medical Center)

Kids with autism retain extra brain connections that other children weed out during development, researchers say in a new study that suggests drugs may be able to correct the issue.

The connections, known as synapses, allow neurons in the brain to communicate with each other. Typically, as children grow, they go through a pruning process to limit the number of synapses.

However, that does not appear to occur properly in children with autism, leaving such youngsters with too many synapses which can affect how the brain functions, according to findings published online Thursday in the journal Neuron.

“It’s the first time that anyone has looked for, and seen, a lack of pruning during development of children with autism,” said David Sulzer, a professor of neurobiology at the Columbia University Medical Center who worked on the study.

The finding could help explain how autism develops and point to avenues for treating the developmental disorder, researchers say.

For the study, scientists looked at brain tissue from 26 individuals with autism ages 2 to 20 as well as samples from 22 children without the developmental disorder, all of whom had died from other causes. In the typically-developing children, the number of brain connections dropped by about half by late childhood, the study found, while those with autism only saw a reduction of 16 percent.

Using a mouse model of autism, the scientists traced the pruning problem to a protein called mTOR. They were then able to treat the issue in the mice using the drug rapamycin.

While the medication may not be safe for human use, the researchers indicated that other drugs could potentially be developed to correct the oversupply of synapses.

“The fact that we can see changes in behavior suggests that autism may still be treatable after a child is diagnosed, if we can find a better drug,” Sulzer said.

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Comments (18 Responses)

  1. Whitney says:

    I would think more study needs to be done on the brain in general. Closing down one synapses because TOR did do so without understanding the repercussion might have a cascading effect worse than autism itself. If you close down a synapse of the brain how do know it does not leave the person in vegetable state or even a paralyze. Even then the what if closes more than the targeted synapses of the brain and that leads to death.

  2. VMGillen says:

    I agree with Whitney – but would also like to point out that lacking an etiology, the ASD diagnosis remains a collection of symptoms, which may or may not respond to specific interventions. I worry about drugs, I worry about surgery, I worry about anything that is irreversible and not fully understood. I worry about big pharma’s profit motives, too. Finally, I worry that too many parents, carried away by their immersion in desperation (and I phrase that very carefully) will try anything… No wonder I’m getting gray hair!

  3. Wayne Rohde says:

    Interesting concept for a study. Since many of the children with severe or moderate autism have incurred a brain encephalopathy from an environmental hazard assault, this could explain why they regress.

  4. Sonja Luchini says:

    What I wonder, though is if my son was given a synapse “pruning”, would he have the instant-photo recall or hyper-retention that enabled him to get good grades in school? What might seem like a boon or a breakthrough, could also be a process that damages or alters the very thing that makes them brilliantly different.

  5. Denise Baker says:

    It should be noted that the statement “While the medication may not be safe for human use, the researchers indicated that other drugs could potentially be developed to correct the oversupply of synapses,” could be a bit misleading. The article to which the writer refers found that the treatment was not effective for mice with permanent pruning deficiencies, but rather only for those that scientist had induced the condition in. This means that the drug is not only unsafe for human use, it would also be ineffective. The difference is important because the first interpretation makes it sound as though a drug has been identified, but just needs to be made safer for humans – sadly this is not the case yet and there is much to be learned about the mechanisms at play. Nonetheless, this is a critical finding that will undoubtedly move researchers closing to understanding these underlying mechanisms that lead to Autism, and perhaps closer to identifying a treatment (for those who would desire to have one).

  6. Debra says:

    I appreciate the study, but like Whittney I won’t be too quick to jump for joy until further research is done and a safe drug is determined. The later being far more difficult than the first! And, I am not sure why a drug is always the preferred treatment for medical ailments anyway?! Medication has not been as effective as ABA in the treatment of symptoms autism so far. Probably better would be to find out how to brain train and somehow create results naturally. For example, use this information to determine if certain therapies like ABA, ST, OT contribute to a neurotypical effect. But this does seem to be a step in the right direction. Therefore, Nice work!

  7. Jon K. Evans says:

    NOW WAIT A MINUTE! I don’t know that I would want to reduce ANY NUMBER OF SYNAPSES-given that the process of AGING already prunes the number of these synapses anyway. In fact, I would think that these extra synapses would serve as an insurance policy against Stroke, Alzheimer’s Disease, or some other form of catastrophic neurologic event.

  8. Dean Bostedor says:

    Like with any brain meds, it’s all bird shot to your brain and you’re playing with fire. Unless you know on a person’s individual level, which neurons need the “pruning”, and you can target those individual neurons with a chemical drug (which you can’t), you are rolling the dice (and who would subject their child to this) that you’re not killing off synapse that are going to cause other issues. This is great news though and a big step forward!

  9. Duff says:

    As interesting as this study is, it has to be understood as another clue, rather than as a prescription for a cure. A normal process for ‘pruning’ synapses would necessarily involve the ability to identify the synapses to prune as well as having the tool (mTor) to prune them. I suspect that the ‘pruning’ occurs on the synapses that are seldom, if ever used. If that is the case, giving the child the ‘tool’ might very well prune their little used synapses for understanding speech, language and interpersonal cues – the very ones that we work so hard to build with ABA. Its great that we now have the research $ to support this type of work – but a lot more needs to be done before a treatment can be developed.

  10. Wilymech says:

    I am not leaping for joy. The problem this research could be apply to other disorders such as Parkinsons and Alhiezemer treatments where the synapses fade or are gone. The real problem is we don’t know enough about human brain, genome, or the genetic structure of the human race. I am not a fan of the cure movement in autism are the people miserable because they are not as social as some. No. The society problem that it is not tolerant or open minded to accept anyone who is different. I understand that if the Autism is severe and not mild to moderate autism for a cure. It is another thing that offends me that the Neurotypical makes people with autism to absolutely miserable because they cannot read emotion or react they way they do.

    I mean look at what the Neurotypical done so far they created religious wars, genocide, and global warming through their own greed. They fight hard to justify the wrong they did and just as much they justify their intolerant views of others who are different regardless of being Autistic or not. This applies to gender, ethnicity, gender preference and disability. They also scream bloody murder when NT feelings and hypocritically they go around trampling others feelings as well. The NT expect their feelings to respect but at they same time ignore others because it is inconvenient. When they justify hurting feelings someone else with autism their response is that person does not have feelings or doesn’t understand. The common complaint is that we do not have enough feelings and feel a bit more. Neurotypicals believe everything exist to their advantage alone and there is no room for people who are different. I honestly do not want to be like them and be a hypocrite. I do believe the curebies need to look real hard in the mirror and quit sugar coating human nature because some of it is very ugly. After all NT are the ones who taught autistic what intolerance is.

    This research has potential to do so much good for other diseases and I do not want to be overlooked in zealous nature of the curing people with autism.

  11. Mark says:

    I applaud that someone is looking at medical, not psychological discovery as to the origin of the issue! I pray that when/if a solution is found, it won’t be too late for those that are rapidly becoming adults!
    The synapses are obviously an issue, my son was tested with a spect (sp) scan and we found his synapses were extremely active, much more so than the norm. This was consistent throughout the brain, exclusive of the frontal lobe. I think that needs to be looked into more deeply.

  12. Bessie says:

    I really don’t see what this study has to do with autism. The rats did not have autism. Obviously if you give a rat any drug it will change their behavior. I wonder what else is changing. This talk about pruning away brain connections is ridiculous. It reminds me of when neurologists would cut away parts of the brain to cure schizophrenia (Lobotomy). Some of us have forgotten how harmful that was but not all of us. I am sorry but this study seems like nonsense.

  13. Lynn Johnson says:

    This could be HUGE for those kids like my son, whose sensory overload disrupts all aspects of life. Certain noises and sensations trigger serious self-injurious behaviors – and he can’t learn when his brain is in such an “over-load” state, which at times, and this is often, renders ABA useless. The damage/malfunctioning of the brain must be corrected in order for progress to be made. The autism that my son suffers from is DEVASTATING – we need answers and he needs help.

  14. ivanova smith says:

    interesting article but I am not interested in being cured. I like being the way I am and so what it means I have more synapses then neurotypicals. that cool actually. the only way I can see autistics going for this if it weaken the extreme sensory issues. like I like to not be in pain every time I hear some open a squeaky door. but their parts of the autism I like, like the extreme focus and the repetive behavior I don’t mind either. and I am concerned that the pill could be forced on autistics which would not be good because it make a real like X-men situation.

  15. kasey says:

    The reference to environmental contaminants is appropo since it may inhibit the mechanism that triggers the normal pruning of the synapses. Repeated oxidative stress has been implicated, as have chemicals and metal toxicity to provide that biochemical stress. Hg can be checked in urine propophyl levels. I also believe that once these abberations (for lack of a better word) occur they are then passed on to your offsping. So alteration of chromosones or expression of genes may control this trimming in offspring. Perhaps the research on mitrochondrial dysfunction – the lack of energy production plays a hand – in there not being the necessary energy or chemistry to prune correctly. I watched my toddler change and later traced vaccine lots and he got 350mcg’s of ethyl mercury in his first 18 mo. in thimerosal. I watched language regression. He also has a brain cyst which is probably environmental or oral mercury exposure – my best guess. Aracnoid cysts are fairly common – yet no one is looking for the CAUSE. Just like this incorrect pruning. Why not do something like bioassays of the autistic kids tissue, or blood, or urine or hair and look for high levels of what are now obiquitous pollutants and contaminants. The gold standard of double blind studies – won’t help find the cause – at all. It’s geared toward increased drug use.

  16. Karen says:

    I don’t see very much coming of this for people with Autism any time soon, if ever. I don’t believe medical intervention is the answer for Autism. Once everyone gets over the idea that people with developmental or intellectual disabilities should remain calm and sit in chairs quietly to make the rest of the world feel more comfortable, maybe then we will stop looking for medication as the answer to happiness. I know some have more severe sensory issues and aggression but as long as people think medication is the way, no one really fully utilizes other resources like behavior modification, OT and SLP, etc. For the most severe ASD kids, I believe these interventions have to be started early, in the home with the family. Parents still have the primary influence on their children’s overall development…not the schools and outsiders. Children of any state of development respond to people who love and care about them. I’m not against medication if it’s the right answer but this sounds very SciFi.

  17. fRANK says:

    That’s an interesting finding. Earlier research done at the University of California, San Diego, found that with individuals with the diagnosis of Autism had less Purkinje ( I think that’s how it’s spelled ) cells than the average person. The Purkinje cells connect the portion of the brain that is located in the back of the head to the frontal lobes. These cells, if I remember correctly, assists with the transfer of information and assist with the development of other parts of the brain. People speculate that the loss of Purkinje cells afftect the frontal lobes that is so often seen in individuals with autism.

  18. Bessie says:

    Yes. I agree that we should focus on teaching children the skills that they need (we do this for all children). We are not going to find answers in clipping synapse or anything else. I don’t understand why neurologists insist that we can improve people’s functioning by clipping away parts of the brain. I don’t understand why we even pay much attention to neurologists. It is good that they have the desire to help but their methods are clearly lacking and outdated.

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