ADHD as Developmental Disorder

[Amtram]

Here's the abstract for "Development of cortical surface area and gyrification in attention-deficit/hyperactivity disorder." It's an interesting idea that might have some potential for explaining why some people have symptoms that persist and some do not. Rather than simply measuring volume of brain structures at a fixed point in time, this study looked at developing brains over a period of several years. It appears to show that in some cases, there was a developmental delay, but development reached or came close to normal at the end of the study.

Next would be figuring out how to discern between delay and disorder. . .

[sarahsweets]

Amtram I so want to understand your threads can you dumb the basics down for me on this one?

[Peripheral]

http://www.neuroanatomy.ca/functiona...eral.html?id=1

[Peripheral]

I am not a professional.

This explaination is very general,

and is missing a much more complex explanation.


There is a cover about 2 to 4 mm,

that covers brain (the cortex.)


Both hemispheres have

a front cover

top cover

side cover

and back cover.

(all "covers" are parts of the cortex)


Each different cover "works" with,

other covers and brain parts.


Each cover has different role(s),

in the brain functioning as a whole.


The front covers are involved in self regulation of the brain.
(emotional, ,attention, inhibiton,hyperactivity,etc....ADHD)



People with ADHD,

Have thinner cover "bark" in the front part of the brain, (prefrontal cortex).

Especially in the right hemisphere.

(That makes ADHDers more sensitive,

to internal and external stimuli.)


I think the researchers want to know?


Does having a "thinner" front right cover of the brain,(prefrontal cortex)(ADHDers)

cause a "secondary delay" in the development of the top,

side and back covers of the rest bark (cortex)?


As well as a delay the development,

of other parts of the brain,

that exist under the "bark".


In my opinion,

the conclusion of the research is:


The "primary" underdevelopment of the right front cover (cortex),

does cause a "secondary" delay of maturity,

in other "covers" and "parts" of brain,

by approx 1.9 years.


The right brain hemisphere "covers" and "parts",

are more effected,

by the delay of the right prefrontal cortex,

than the left hemisphere.




The research does tell us.

The overall delay in brain development.(the secondary delay)

does eventually "catch up"

to the "normal" maturity of the brain development ,

as a non- ADHDers.

(but takes longer by approx 1.9 years).



What the research doesn't tell us is:


Does the "primary delay associated" with ADHD,

(in the thinner bark of prefrontal cortex.)

catch up to the development of "normal brain"?


I don't think in most cases of ADHD,

the right prefrontal cortex does fully develop to normal size,

in adulthood.


Although it may be possible for some people,

with very very mild cases of ADHD?


Realistically,

in adulthood some neurodevelopment is possible.

But not nearly as rapid

as the rate of brain development,

in early infancy.









.

[Flory]

thanks for the adhd friendly version geronimoooo

[Peripheral]

http://www.nature.com/pr/journal/v69...9201196f1.html

[JOHNCG]

Originally Posted by Amtram

Here's the abstract for "Development of cortical surface area and gyrification in attention-deficit/hyperactivity disorder." It's an interesting idea that might have some potential for explaining why some people have symptoms that persist and some do not. Rather than simply measuring volume of brain structures at a fixed point in time, this study looked at developing brains over a period of several years. It appears to show that in some cases, there was a developmental delay, but development reached or came close to normal at the end of the study.

Next would be figuring out how to discern between delay and disorder. . .

You might find this study interesting:

Rubia, K, Neuroanatomic evidence for the maturational delay hypothesis of ADHD. (2007). Proc Natl Acad USA 104 (50): 19663-4.

Regards,

John

[Amtram]

Thanks, JOHNCG. BTW, direct links to Pubmed or other journals are OK, even if they're just abstracts and you have to be a professional or subscriber to get the full text. There aren't any alternatives. Your article, fortunately, has a free full text at http://www.ncbi.nlm.nih.gov/pmc/arti...3/?tool=pubmed, which I will look at later.

As for the simplification, here's some more of it. . .

Here is an image of an infant brain (I'll let you click rather than embed, in case images make you queasy. . .) And here is one of an adult brain. You'll notice that the infant brain is much smoother than the adult brain. That's because as the brain develops and increases in volume, it also increases in surface area. All that surface area has function, and all those wrinkles exist in the interior as well. MRIs show much more unbroken mass in an infant brain, while an adult brain looks more like a twisted maze - lots of dark curvy lines that indicate spaces between surface areas of the various brain structures.

So size and surface area indicate development, and a lot of specified structures can be isolated in images by the edges of those surface wrinkles. We can look at an image and say "This is the left frontal lobe. This is the parietal lobe. This is the cerebellum, the amygdala, the hippocampus," and so on. Using the scans and mathematically calculating the volume of these areas based on both the area of the space they occupy and the amount of surface, we can compare the development of an individual, or compare an individual versus normal developmental size for his/her age. A more developed structure will both occupy more space and have more "wrinkles" from increased surface volume.

Most studies have focused on volume alone. There have been some pretty consistent results from study to study that the volume measurement of various structures (primarily frontal lobes, but also the hippocampus and amygdala and occasionally others that might influence secondary characteristics of ADHD) is smaller in people with ADHD than it is with population-based norms by age and gender.

This study, on the other hand, focused on the surface area primarily. It was watching the pattern of development of those wrinkles and checking to see if there were a correlation between the surface area of the prefrontal cortex (those frontal lobes) and the presence/severity of ADHD symptoms in 234 diagnosed children and 231 typical children over the course of 7 years (although the abstract doesn't specify this, several articles based on the study mentioned starting ages of 10 and concluding ages of 17.) It showed that the development of the right frontal cortex's surface area was significantly delayed, with the ADHD children reaching the median amount of surface area almost two years later than the control group did, with a similar but less pronounced delay in the left.

I didn't want to link to the various articles, because even though they contained details not in the abstracts, they also made some assumptions that might or might not have been supported in the actual research. One of these was that since the development was delayed, that meant that there was strong evidence that people outgrow ADHD. Well, besides the fact that we all know that's not necessarily so, the study didn't follow the kids after the age of 17, so that conclusion isn't supported by the study. Since I can't see the whole thing, I don't even know if there continued to be a difference in surface volumes at the conclusion of the study, or whether there had been any testing at the end to compare surface development relative to the mean with persisting symptoms.

The implications of this study will depend on how it's put to use. It's another tool in validating that there is physical evidence for ADHD as an actual "thing," whether it's a developmental delay or a developmental disorder. It shows a strong correlation between the physical structure that is responsible for most of the functions in which ADHDers experience a deficit. It could also lead to ways in which imaging could be used as a diagnostic tool, so that early intervention could be justifiably recommended.

Eventually, as our understanding of the genetic/epigenetic processes improves, pinpointing the first signs of these specific developmental differences could lead to treatments to offset some of the delays or even eliminate the deficits - don't be holding your breath on this, because it's not happening any time soon, but one day it could. Being able to pinpoint the exact developmental stage at which the delay begins can tell us how to find the process that triggers it.

But right now, it just means that there are some kinds of wrinkles we actually want!

[Peripheral]

Amtram,

Thanks for the OP information.

and the simplification.

I never considered a secondary delay,

from the primary delay.

Very important, thanks!


I also never research "gyrification" much before.

And found the topics very interesting.


I wonder what the same concept (research) would be like from the ages 1 to 7?

(especially in regards to the primary delay?)

Will be working on topics from this information for a longtime.

There seems to be many reasons that a primary delay could occur?

I will make a list and present it later,

and see what other people can add also.

Multifactoral ADHD?

Thanks GBYR.

[Amtram]

I would think that this age group was chosen in part because the testing and self-reporting would be more accurate than it would be at earlier ages. It wouldn't surprise me to see similar delays at earlier ages, but other than my best guess, I can't say why this range was chosen.

[Peripheral]

Originally Posted by Amtram

I would think that this age group was chosen in part because the testing and self-reporting would be more accurate than it would be at earlier ages. It wouldn't surprise me to see similar delays at earlier ages, but other than my best guess, I can't say why this range was chosen.

In my opinion,

Periods of different rates of development is the reason.


ADHD symptoms must be present before the age of seven.

Therefore,

the primary delay in the prefrontal cortex,

would need to be present before the age of 7.


The researchers wanted to "measure" for the secondary delay,

that occurs as a result of the primary delay,

in the prefrontal cortex.


Any secondary delay would only be able to be measured,

with any accuracy,

after the approx. age of seven.


The critical time of development,

for the primary delay would be:


-Second trimester, third trimester , birth til the age of 7.

(90% of the human brain develops, (before the age of three)


The time of development for the secondary delay would be:


-Approx. the age of 7 til adulthood.



Side Note: The primary delay occurs during the critical time of rapid development.

(The critical time of rapid development is when most of brain development occurs for the first time.)


The secondary delay occurs over a longer period of time.

because it does not occur during the critical time of rapid development.





.

[Peripheral]

Give or take,

90 % of the adult size brain,

develops before the age of 3.

If it takes 18 years for the brain to reach adult size.

That means it takes 15 years for our brain to grow 10%.

10% = 15 years

90% = 3 years


The infants average rate of neurological brain development,

declines dramatically by the age of 18.


The rate of neurological brain development,

is approx 5 times faster,

in the first three years.


The same childs average rate of neurological development over the next 15 years,

is 5 times less.


During the first 3 years of life,

lots of sensitive neurological "components" are being 90% developed,

for very the first time.

Many of the final connections needed for "normal" neurological brain development are use-dependent.

During these three years of rapid brain development,

is when humans develop most of their "normal" self-regulation "skills".

That people with ADHD are lacking.



.

[Amtram]

However, another thing to keep in mind is that on average, the frontal lobes in all humans continue to develop until sometime between the ages of 24 and 26. At that point, pretty consistently, behaviors will markedly differ as far as the amount of risk/consequence assessment taken into account before acting. It explains a lot about that sense of invincibility that causes younger people to take impulsive risks. Behavior without thought about outcome in general takes place more frequently before this stage.

Afterwards, an impairment might not eliminate these behaviors, but there might be a comparative improvement depending on the degree of that impairment. It's an example of a set of behaviors directly tied to a particular brain area that has developmental milestones at later life stages.

The problem with lumping the entirety of brain growth into specific age groups is that it minimizes the importance of recognizing that certain areas of the brain reach their own particular growth milestones, and change or mature at different points. While neuroplasticity may be at its highest prior to a particular age, there are other very significant changes that occur at later developmental stages in specific functional areas.

Thus, relating total brain volume during specific ages to adult functionality, emotion, or behavior ignores the more important aspect of the development of individual areas of the brain. That's not to say that it's not important, but that it's not the single most important thing. Anything that tries to simplify a cause/effect or correlational event in something as complex as the human brain is going to compromise our understanding rather than improve it.

For example, we can tell children to be nice, share, don't hurt others, etc., and they might obey, but they absolutely will not be able to understand the innate reasons for considering the feelings of others until around the age of seven, when they acquire theory of mind. A young driver might see the consequences of the impulsive, inattentive mistakes among his friends, perhaps even experience them himself, but until his mid-twenties, still not think before texting, drinking, speeding, etc., until after that ability to foresee results has developed in his frontal lobes.

So really, knowing at what ages overall growth rates are fastest is of some importance, but not nearly as much as knowing what cognitive and behavioral changes occur at each stage of development of the area of the brain that controls them.

[Peripheral]

Originally Posted by Amtram

However, another thing to keep in mind is that on average, the frontal lobes in all humans continue to develop until sometime between the ages of 24 and 26. At that point, pretty consistently, behaviors will markedly differ as far as the amount of risk/consequence assessment taken into account before acting. It explains a lot about that sense of invincibility that causes younger people to take impulsive risks. Behavior without thought about outcome in general takes place more frequently before this stage.

Afterwards, an impairment might not eliminate these behaviors, but there might be a comparative improvement depending on the degree of that impairment. It's an example of a set of behaviors directly tied to a particular brain area that has developmental milestones at later life stages.

The problem with lumping the entirety of brain growth into specific age groups is that it minimizes the importance of recognizing that certain areas of the brain reach their own particular growth milestones, and change or mature at different points. While neuroplasticity may be at its highest prior to a particular age, there are other very significant changes that occur at later developmental stages in specific functional areas.

Thus, relating total brain volume during specific ages to adult functionality, emotion, or behavior ignores the more important aspect of the development of individual areas of the brain. That's not to say that it's not important, but that it's not the single most important thing. Anything that tries to simplify a cause/effect or correlational event in something as complex as the human brain is going to compromise our understanding rather than improve it.

For example, we can tell children to be nice, share, don't hurt others, etc., and they might obey, but they absolutely will not be able to understand the innate reasons for considering the feelings of others until around the age of seven, when they acquire theory of mind. A young driver might see the consequences of the impulsive, inattentive mistakes among his friends, perhaps even experience them himself, but until his mid-twenties, still not think before texting, drinking, speeding, etc., until after that ability to foresee results has developed in his frontal lobes.

So really, knowing at what ages overall growth rates are fastest is of some importance, but not nearly as much as knowing what cognitive and behavioral changes occur at each stage of development of the area of the brain that controls them.

If we need to have symptoms before the age of seven,

anything that would happen after the age of 7 ,

would not have a large contribution to development of ADHD.

We must have symptoms before the age of seven.


The majority of a humans self regulation is developed by the age of 3.

7 years old is not the average ,

it is the limit for the presences of symptoms,

for ADHD diagnoses.


Anything that happens after the age of seven would be considered "secondary delay".

The brain is highly plastic to both good and bad circumstances.

From birth til about 7.(starts to decline at about the age of 4.)


All people with ADHD will have developed ADHD before the age of seven,

according to diagnoses criteria.


.