ADHD, Autism, and Brain Development
November 13, 2007 by Kristina Chew, PhD
Filed under Health
For those with ADHD, the brain matures in a “normal pattern,” with delays of three years in some regions, according to a just-released study in the November 12th Proceedings of the National Academy of Sciences. Notes Scientific Blogging:
In both ADHD and control groups, sensory processing and motor control areas at the back and top of the brain peaked in thickness earlier in childhood, while the frontal cortex areas responsible for higher-order executive control functions peaked later, during the teen years. These frontal areas support the ability to suppress inappropriate actions and thoughts, focus attention, remember things from moment to moment, work for reward, and control movement – functions often disturbed in people with ADHD.
Circuitry in the frontal and temporal (at the side of the brain) areas that integrate information from the sensory areas with the higher-order functions showed the greatest maturational delay in youth with ADHD. For example, one of the last areas to mature, the middle of the prefrontal cortex, lagged five years in those with the disorder.
The motor cortex emerged as the only area that matured faster than normal in the youth with ADHD, in contrast to the late-maturing frontal cortex areas that direct it. This mismatch might account for the restlessness and fidgety symptoms common among those with the disorder, the researchers suggested.
They also noted that the delayed pattern of maturation observed in ADHD is the opposite of that seen in other developmental brain disorders like autism, in which the volume of brain structures peak at a much earlier-than-normal age.
This last paragraph especially intrigued me: I’ve read before about how a process called “pruning,” which is thought to eliminate “faulty connections” and also to optimize the “functioning of the feed back control system,” can occur at an accelerated rate in autistic children. It is also thought that large brain size in autistic persons may be an indication that normal pruning does not occur. What happens, or does not happen, or happens differently, in the brain of a child with ADHD vs. one with autism? What differs about their genetics?
As I’ve noted, my husband Jim has ADHD (diagnosed in his adulthood). Jim has an almost symbiotic sensitivity to what Charlie’s experiences, especially in regard to sensory processing. They are both uneasy in small, close spaces (where I am fine); both think better while in motion, among other similar traits, and I’m ever curious about overlaps and differences between ADHD and autism, and the neurology of both. I guess I’m the unusual one in our little family…..
I’m pretty sure that, intellectually, I peaked around the age of one. It’s been downhill ever since. I’m over-pruned.
Strangely, my brain has shown remarkable development in it’s pseudo-cortical spandex. I’m enjoying that.
Thanks for this. I’ve been doing some reading about ADHD and Autism. It has been suggested, by the wonderful people working with my son at school, that some of Patrick’s behaviours are leaning towards ADHD (as in they don’t fit into the autism profile). They aren’t interested in us drugging him (which we can’t do because of the seizures anyway) but think the identification will help others be more patient with him.
I’m still thinking.
Now I’m confused–I have both ADHD and autism! How’s that supposed to work?
Honestly, I think that autistics get an ADHD diagnosis frequently when they don’t get ADHD. It’s an issue of differing focus, and if you’re focusing intensely elsewhere it looks like a lack of focus. So I’m not sure that actually does work, to be honest.
Cliff
Interesting…my son, like chaoticidealism, has both ADHD and autism. And no, I don’t think either one is a misdiagnosis–it certainly appears they can co-exist, at least in some instances.
My son was diagnosed with both ADHD and Asperger’s, similar to some here, at the same time (comorbid, as they call it, as opposed to getting an ADHD dx and then later getting an AS dx.) His CORE evaluation by the school system also turned up both. My understanding is that this is actually pretty common.
He takes medication for his ADHD which helps him tremendously in terms of attention and impulse control. But what really surprised me is how much the medication helped reduce his perseverative behavior and pallilalia (like echolalia but instead of repeating what someone has just said, he repeats something he heard at another time and in another context.) It’s a short acting med so I can see the difference in these behaviors when the medication wears off.
In many ways, I feel like the ADHD aspect holds him back academically way more than the Asperger’s does even though people perceive AS to be a more “severe” diagnosis.
I have never heard of pallilalia—my son does this very frequently. There’s “something of Asperger’s” in my husband though he is very empathetic and emotionally. Interesting what you say about the ADHD holding your son back more—-did he get both diagnoses at once?
Still too soon to say when Charlie’s “peak” is, was, or will be! He’s never had an ADHD diagnosis though “attention” is something that many notice he struggles with. He did take Ritalin for a few days and it did help him to “focus,” but it made him (this is the best word I can think of to describe this) skittish and alarmed all the time.
Is there a word, do you know, for feeling compelled to read some words aloud? I seem to process unfamiliar words better (and some words I just like a lot) if I say them out loud while reading. Echolalia is one of them: I just like the sound, and say it out loud most times I see it written. This is especially true if I’m alone and no one will laugh at me.
Eleanor’s older sister has an ADHD/inattentive type diagnosis, and they are like yin and yang.
The older can’t remember where anything is and the family joke is if you can’t remember, ask Eleanor. The place at the dinner table with the big mess–big sis. The perfectly bussed place with napkin and placemat symmetric–the younger.
Eleanor has significant language delays and processing issues, her older sis sometimes couldn’t be quiet if her life depended on it. Although ADHD is considered the “milder” diagnosis, in our experience a lot of structure, patience, apropriate supports and teaching is required, esp. if someone is not going to “grow out” of it, as I suspect may be the case in our family. People can be rough on a kid with ADHD because it can be interpreted as plain bad behavior, and without obvious disability, we have been told even by some teachers that they don’t believe that ADHD is real and that all that is needed is to “get a grip”.
I can see parts of both of us in the two–although the older definitely takes after her dad and the younger after me.
We all have big heads:-/.