Skip to comments.Fear centre is shrunken in severely autistic brains
Posted on 12/10/2006 3:48:41 PM PST by neverdem
A hyperactive amygdala may cause its own self-destruction.
The more severe the social dysfunction of an autistic patient, the smaller the part of their brain that governs fear-response, according to a new study. The results have scientists wondering whether some of the symptoms of severe autism are due to the brain becoming so overworked that it attacks its own cells.
The amygdala a small part of the brain that governs emotional responses, such as fear is thought to be important in autism, as it helps to govern social behaviour.
To examine the relationship, Richard Davidson and his team at the University of Wisconsin in Madison, decided to try and match amygdala size to the development of autism. They took MRI scans of 28 male autistic participants ranging in age from 8 to 25 years, and calculated the volume of their amygdala.
The researchers then looked at whether the patients tended to avoid eye contact a well-known symptom of autism. Eye-tracking equipment was used to watch how the participants reacted when looking at images of emotional faces: autistic children tend to avoid the eyes in such pictures, and are slower at distinguishing facial expressions.
They then compared the extent of eye-contact avoidance and the particpant's age with the size of their amygdala. The results showed that the most severely affected, older subjects had the smallest fear centres in their brain.
"Older kids with smaller amygdala are the ones that tend to avert their gaze more," says Davidson.
In general, young austistic children have relatively large amygdalas. But older, teenage autistics have relatively small amygdalas. The more severe their symptoms, the new work shows, the smaller this part of the brain.
The results are consistent with the theory that a hyper-excitable amygdala in young autistic children may result in cell death and the shrinking of this part of the brain. Davidson plans to study the cells in more detail to test this theory.
It wouldn't be the first time it has been suggested that the brain may attack itself in response to a mental condition. Previous studies have shown that the amygdala is smaller in cases of severe recurrent depression, perhaps as a result of early hyperactivity.
Have you noticed the new related links layout on PubMed?
Okay, I don't knwo much about neurology, but was Amygdala the princess who married Darth Vader?
But if the article thesis holds, they would become fearless. The ones I have seen, were not.
Yes. But when he was young and fearless.
Wasn't he Princess Diana's "fiance"?
Imus always used to talk about the possible effect of mercury in infant immunizations causing autism.
Autism isn't a joking matter when your child or grandchild has it.
I indulge myself in what I, appealing to Biblical scholars, call reverential facetiousness. Things I take very seriously I joke about. HOu ought to hear me on theology -- or maybe not.
Naturally that's not always understood or appreciated. I regret any pain I might have caused. Seriously.
The Institute of Medicine did a report saying there's no correlation between infant immunizations causing autism. If there was you would see a decrease in the incidence of autistic spectrum disorders because thimerosal, the mercury containing preservative, isn't used in unit doses, i.e. the way kids get their shots now for a few years already. IIRC, thimerosal is only used in multi dose annual influenza vaccines.
My friend's little autistic son knew no fear. He had to be watched constantly. Tried to climb on the railing of our deck, which was three stories high. Had no concept of danger.
What has happened is that the definition of autism has been broadened as to be almost unrecognizable. This makes the number not credible, IMO.
The decrease has been established. Shhhh, they don't want the public to know.
Autism Rates Drop After Mercury Removed From Childhood Vaccines
03 Mar 2006
An article in the March 10, 2006 issue of the Journal of American Physicians and Surgeons shows that since mercury was removed from childhood vaccines, the alarming increase in reported rates of autism and other neurological disorders (NDs) in children not only stopped, but actually dropped sharply - by as much as 35%.
Now a lot of behaviors are diagnosed PDD possibly in the autistic spectrum. It has broadened the diagonis a little too far I think, so those truely affected aren't taken as seriously. My nephew is autistic. I love him dearly and hope that with the therapy he is recieving he will be able to lead a somewhat normal adult life, but I know there is only a slim chance of that.
The following term was not found: Journal of American Physicians and Surgeons[Jour].
Something isn't right, and I don't know it is. Here's a link to the paper:
Maybe they got something finally.
Why would you want to do that, Tom? There's always addictinggames.com to burn up half a day.
I can easily burn half an hour at solitaire, and that's just card-flipping. Sometime today, though, I've got to get ready for the Omnibus class I'll be teaching this evening...
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