Ferrari Hind-Brain, Dune Buggy Frontal Lobes

Fads in education tend to be oversimplified, and the newest of fads is no exception.
Think about this current catch-phrase in education for a moment: Brain-based learning.

People are writing curricula and textbooks and making a lot of money from this phrase.

Whenever I hear it in a seminar or discussion, I am always tempted to raise my hand and ask, "Isn't all learning brain based?" Because it is. At least the learning we are supposed to be talking about when we are talking about educating children in school.


The other one--and it's been around for a while now--is the whole left-brained vs. right-brained cliche. You know it: right-brained people are so much more enlightened and spiritual than those who dwell in the concrete-sequential left brain. Except . . . it appears the religious experience is partially mediated by the left temporal lobe. Sorry, wrong hemisphere.

There is some truth to the idea that there is a hemispheric division of duty in the brain. In males, language processing is normally in the left hemisphere, whereas certain associations of the images that language evokes take place in the right hemisphere. But females tend to distribute language processing across the two hemispheres, and since the female corpus collosum tends to be larger and denser and signals move across it more rapidly, why shouldn't they?


Guys, this may be why you cannnot win at verbal tete-a-tete with your mothers. But I digress . . .

Consider the paragraph above the digression about guys. The word "normally" is operative there. Because neuroplasticity is such that people do all kinds of things with parts of their brains normally reserved for something else. And there are those on the autism spectrum that make an art of it, experiencing synasthesia, the ability to smell color, for example, or hear shapes.

The semester's work that I just finished (thank Heaven and the PsychInfo data base) was about differences in sensory processing between people with Autism Spectrum Disorders (ASD), and typically developing individuals (NTs). I looked at visual processing, but I could have just as easily looked at other senses. In all of them it is the same. Autistics process differently, using different parts of the brain on both the right and left sides, because the real difference is between front and back.

Uta Frith, one of the researchers about this, says that non-autistics have a drive towards central coherence. NTs will look at the picture, and initially see the parts and then the whole, but they do it very quickly, and then prompty forget the details in that drive to the big picture. Many with ASD do not. Rather, their focus on the local processing is intense, and they remember the details and focus on them, sometimes not seeing the big picture at all. This makes them very good at the Block Design subtest on the Weschler Intelligence Scales (WISC or WAIS) and very bad at the Comprehesion portion.

And what portions of the brain light up on fMRI when these kids are doing tasks like BD? It appears that they shift their function backwards, to more local function. Some researcher think they mentally move shapes needed to match detail to the whole, rather than place the figure in working memory, like NTs do. The NT strategy for embedded figures and block design has many more top-down features, and thus on these kind of tasks, individuals on the spectrum are more efficient and work faster. And in time-constrained situations, they also tend to be more accurate.


These visual processing differences appear to be primary in nature, by which I mean that they show up on both social and non-social tasks. It is true that autistics process faces differently, with much of the activations happening outside the fusiform gyrus' face area. But in ASD samples, processing of right-side up and upside down faces is equally as fast, whereas in NTs it is not. This may mean that it is perception that is fundamentally different, and that it is possible that many of the other characteristics of autism flow from it, rather than from a fundamental difficulty with social interaction.

Some researchers believe that these perceptual differences are the root of savant skills like card-counting, calendar calculating, or perspective in drawing.


There are still arguments in the field about whether of not this "weak central coherence" is compensation for a deficit or whether it is an enhanced perceptual function in its own right. There is evidence that those with ASD do engage in top-down control (from the frontal lobes), and that the local perceptual functioning (bottom-up) is more efficient. But there is also evidence that the observed top-down processes are qualitively different than those in NTs.

But it is safe to say that perception in ASD (and to some extent in ADHD as well) is fundamentally different than in NTs.

fMRI activation maps do show difference across the hemispheres, but also from the back of the brain to the front. In autistic perception, the activated areas are more scattered throughout the brain, and different areas light up for perceptual tasks than in NTs.


All of this means that the structure of intelligence is different in ASD. On the new WISC and WAIS scales, the Working Memory and Processing Speed indices result in much lower scores than the norm, whereas the Perceptual Organization and Verbal Comprehension are much higher. This is true within the individual scores, so that any full-scale IQ score is essentially meaningliess. When fluid intelligence, which is the ability to reason abstractly, is measured alone, as it is on Ravens Progressive Matrices, scores are generally very high in high-functioning autism (HFA) and Asperger Syndrome (AS).


One problem with intelligence testing done by educators as opposed to those done by professional psychologists, is that they often calcuate a FSIQ when the gaps between subtests and indices are so wide as to make that number meaningless. This meaningless number is then used as a measure of a child's potential, and is attached to him/her, sometimes for years, and limits what the child is allowed to do in school. To add insult to this injury, schools are designed for the average (and with NCLB, the slightly below) child, and instruction is auditory-sequential in nature, which relies heavily on auditory working memory and processing speed. This is why school is a difficult place for a child on the spectrum to actually get an education.

The rules are made for NTs. Thus one has to memorize math facts before being allowed to take higher math. And one must take algebra before geometry. Neither of these Stupid Neurotypical Rules (SNTR: coined by Temple Grandin) make sense for kids who see the world through such different perceptual lenses. The should use a calculator. And take geometry first. And then use hands-on equations for algebra. Even so, the teacher must be able to teach math outside the SNTR box.

Here's the bottom line:

It's not about right- or left-brained people. But we could say that Aspies, Autistics, and ADHD's, all have Ferarri motors in the hind brain, but with a dune buggy control system in the frontal lobes, the drive for them is anything but smooth in the narrowly defined normal of the typical school.

Thinking About Reading and the Brain

I've been thinking a lot about reading this summer, and in talking to others about it, I was given the title of this book:

Proust and the Squid: The Story and Science of the Reading Brain
by Maryanne Wolfe, HarperCollins Publishers, New York, 2007.


Disclaimer: Reading one book does not an expert make! Although I am studying neuropsychology, and I do have a biological sciences background and recent coursework in neurobiology, most of my technical reading thus far has been in general neurobiology, general neurophysiology, and child psychopathology; my interest in these areas has been mainly about differences in visual processing found in children with autism, and also in certain other populations, including a sub-set of gifted children. I have gotten interested in the neuropsychology of reading because I am teaching reading this summer using a unique methodology developed by the Institute of Reading Development. My background helps me understand this book a little differently than the lay reader might, but I claim no expertise in this area. I have downloaded some of the source research studies described in this book, but I have not yet read them. Wolf and her colleagues are the true experts and I urge you to read this book and go beyond it to get the full implications of this work.

Whew! I just had to say that because what I am about to say is personal and speculative and is no way to be construed as having come down from Sinai!

This book is really three discourses in one. The first is about the development of writing and reading as a human cultural technology, and the implications thereof for changes in the connections between relatively fixed structures in the human brain that have not been modified for reading. The second is about the development of reading skills for individuals in literate cultures, how it differs across languages, and the implications of reading for the individual's brain and self. The third is about what may be going on in the brains of those for whom reading does not develop in the expected ways, those who have dyslexia.

All three discourses are interesting and well-explained, and they are all related to the others in complex ways. It is not easy to tease them apart. For example, the development of writing and reading as a cultural technology at the beginning of history (literally!) six thousand years ago, has made changes in neural connections in literate brains that have fascinating implications for the development of each individual reader and has also created within literate individuals a different mode of thinking and self-understanding from those who are not literate. In turn, intriguing new neurobiological discoveries about dyslexia, built on the hypotheses of pioneers such as Orton, demonstrate that reading is not natural to the human brain; rather it relies on older structures and abilities that are useful for other, more innate tasks. Wolf is very good at teasing these stories apart while maintaining the connections among them, and treats the reader to passages about meaning that are quite beautifully written.

I was most interested in Wolf's discussion of the development of the expert reader. When a child first begins to read, certain neural connections begin to form in the temporal-parietal regions of the brain that create associations among nearby primary and auditory centers, primary visual centers in the occipital lobe, and the language centers in the parietal lobe and frontal lobes. Normally, these connections are primarily developed in the left hemisphere, which also provides the exquisite timing necessary for fluency, although some right hemispheric involvement also occurs, the extent of which depends on the language and writing system being read. As the child works on decoding, his brain recruits a great number of neural connections, because the child is a novice. A great deal of gray matter, white matter and energy are required in this laborious process. Feed your children often and well, and give them lots of encouragement through this stage!

When fluent reading develops, more and more of the associations necessary to decoding and parsing written words to extract meaning become automatized, and fewer neurons and neural systems are needed for the task. As reading becomes automatic, the number of neurons needed for the mechanics of it become fewer, and more brain "space" is freed up for the meta-cognitive work that makes reading so valuable and pleasurable. What is really interesting is that these meta-cognitive tasks are done in the right hemisphere, where concepts, patterns, and meaning are associated with the reader's previous experience. Connections are therefore made across the hemispheres and reading becomes an internal dialogue between the reader and his experiences and the words written on the page. This is what makes reading a transcendent experience that creates for the reader the ability to bring herself whole--mind, heart, and soul--into the mind of another, or into wholly imaginary worlds that become real through the act of reading.

Like everything learned, reading does change our brains. The brain is composed of structures that are relatively stable; that is they are much the same in a modern literate person as they were in our Cro Magnon ancestors forty thousand years ago. However, the connections between these structures do change with the development of expert reading, and the weaving together of dedicated neural systems means that the literate person gains a new way of thinking that is not available to the non-reader.

There is a great deal of concern, especially among those of us who could not live without the meta-cognitions that reading has given us, about the decline of reading in American society, in favor of the more completely visual information technologies now developing. And although we know we cannot turn back the clock, we are concerned because we know that the assimilation of vast amounts of information is not equivalent to the ability to think meta-cognitively, reflectively, in the way of an expert reader.

One valid reason for this concern relates back to the issue of timing in the firing of neurons, which primarily developed in the language centers of the left hemisphere for the purpose of sequences. There are "delay neurons" whose job is to slow down neural firing, allowing time for sequencing and decision. Reading, which requires exquisite timing for fluency, supports in turn, time for contemplation and association with experience by the reader. It is not at all clear that the more graphic, iconic nature of the internet will do the same.

From my IRD reading teacher training, I learned that the real bottleneck for developing readers occurs between the stage where the child learns decoding and basic fluency skills, and the stage where the child reads enough to develop the fluency and comprehension required to achieve identification and absorption in works of literary fiction. Almost all American children achieve the first, and thus are not technically illiterate. Fewer and fewer achieve the second. My training manual says the following"

"The reason is straightforward enough: many children don't do enough reading in chapter books...for identification and absorption to become automatic...The reasons can probably be grouped into three main categories. First there is not general, widespread acceptance or understanding on the central importance of Stage 3 goals (i.e. fluency and comprehension enough to support identification and absorption. EHL) and consequently, most schools require an inadequate amount of reading in chapter books... (I)nstead, school reading often focuses on short pieces or excerpts....Second, reading has a hard time competing with electronic media...And third, children who achieve fluency in chapter books late in elemetary school have little opportunity to catch the reading bug before being caught up in all the competing demands of the middle school years."
--Version SU 08 1.5--4/14/08, Institute of Reading Development

In answer to Lisa's question, posed in the comments here, I think that given what we know about reading and the brain at this time, it would be a good idea to limit use of the internet as an educational tool, and to limit also the use of electronic media for entertainment, at least until a child has achieved the Stage 3 goals and can read with identification and absorption in chapter books. In this way we can ensure that the vast majority of kids achieve the neural connections necessary for the kind of associational thinking and reflection that are the gift of the expert reader. Then the internet can become a tool for the creation of ever more diverse associations and the development of new ways of thinking that do not displace those acquired through reading development.

However, we must also continue to remind ourselves that for students with dyslexia, who are using different neural pathways to develop reading, all bets are off. They may need and benefit from technology in ways that do not benefit the majority of our students. But that would be another blog!

I'm closing with Maryanne Wolf's version of Hemmingway's "one true sentence," from her conclusion to Chapter 6: The Unending Story of Reading Development in Proust and the Squid:

"The end of reading development doesn't exist; the unending story of reading moves ever forward, leaving the eye, the tongue, the word, the author for a new place from which the "truth breaks forth, fresh and green," changing the brain and the reader every time."

May her words whet your reading appetite. Go forth and read great books!

IRD Term II Week II: The Engineering Geek Has an Epiphany!

Yesterday, I arrived home at 8 PM after completing the second week of the second term.
Things are going well and I am into a teaching routine now, though I was quite tired from the long week just past, in which I had taught an extra day as a substitute. I also think I need new shoes--the really comfortable sandals I bought in May are now worn out; I am on my feet most of the hours that I teach. I may get five minutes to inhale half-a sandwich and sit down between classes. I think this is the one aspect of IRD that I would change: A dedicated lunch period of 1/2 hour would make the days less physically and mentally stressful. Anyway, this afternoon I will hie myself off the Shoes On a Shoestring to see what they've got!

Last term I had no adult classes assigned to me, but this term I have two.
I am really enjoying helping adults improve their reading and comprehension. In the adult classes, we focus mainly on non-fiction and only do some fiction in the last week of the course. These past two weeks we have been reading Dibs: In Search of Self by Dr. Virginia Axeline. This is an excellent book in it's own right. Virginia Axeline is credited with inventing Play Therapy for the purpose of helping psychologically troubled kids. In this book she tells the story of her interactions with a highly gifted young boy who does not interact with the world. In our discussions of the book in both classes, we have touched on the ideas of respect for children as people, how a child's therapy can heal the family, and also the need not to make snap judgements about a person's abilities and development.
This has been very interesting to me, and the insights from our discussions have given me new insights into my third career--that of a neurospychologist.

Within the IRD curriculum, however, we are using Dibs not only to discuss but to develop improved reading skills and comprehension strategies for adults so that they may take active control of their reading. Active control here means that adults consider their purpose for the reading that they are doing and adjust their strategies accordingly in order to achieve the greatest reading efficiency and also take pleasure from all their reading. What is interesting about teaching adults is that, although they generally do not resist the strategies we teach to the point of refusal, they do complain--vociferously--about them because the strategies feel awkward after a lifetime of poor reading strategies and habits. This is particularly true of the older students. And the engineers.

The Engineering Geek is taking my Wednesday evening class in Santa Fe. He has been complaining off and on over the six years of our marriage about how difficult reading is for him and how unpleasurable it is as a consequence. A few years ago, when I first matriculated for my Special Education MA, I received a flyer from UNM Continuing Ed for a speed reading class. (It was the IRD program, though I did not know anything about it at the time). Being a very fast reader with many academic successes under my belt, I felt no need to take such a class, so I put the flyer in the recycle. The Engineering Geek rescued it (he throws nothing away) and carried it around for the entire summer, but did nothing about it. (This is, I have learned, typical for him. Every project not involved with his work starts out this way. Eventually, I make things happen and he grumbles and then is grateful. Sigh. A woman's work...). So this summer when he learned about my schedule and was fretting about my driving home from Santa Fe on the back roads late at night, I suggested that he take the adult class there and make the drive with me. He grumbled about the cost a little bit, but when I got him a discount, he agreed.

At the first class I discovered one reason that reading was so difficult for him. He reads very slowly. Reading a book slowly is like watching Peter Jackson's The Lord of the Rings movies in slow motion: it allows the mind to wander. A slow reader ends up losing the thread of the story or explanation, and must re-read and re-read in order to remember what was read. But the adult class is a Speed Reading class. So the Engineering Geek was taught the techniques to improve reading speed. I noticed that he was having trouble with them; his technique was jerky, and it appeared that he was still re-reading. I was not sure if he was not comprehending or if he did comprehend but didn't realize it. (This can happen as one learns speed reading). So I listened to him and his partner as they retold what they had just read. The Engineering Geek was having great difficulty finding the words he wanted, which slowed him down and interfered with memory. I was planning of having a conversation with him about it after we did a group discussion

Here is what I thought was going on. Engineers are visual thinkers, and many of them have what Cheri Florance calls Maverick Minds. That is, the visual organization of their thinking is strong that they do not learn to switch to verbal strategies when they are needed. Mavericks rely so heavily on visual memory and cognition that they do not develop the verbal memory needed for certain tasks very effectively. But reading is a primarily verbal skill, even though the visual system is used for information intake. So, I was planning to discuss this with the Engineering Geek in order to determine if this interference was a problem. (This can be a big problem for males, because their verbal centers tend to be far more lateralized in the brain than those of females. Also, the male corpus collosum--the fibers that carry information across hemispheres--is smaller than that of females. It appear that females are far better "wired" for verbal thinking than males).

So, as I said, I was going to bring this up with the Geek. But when I approached him during the next independent reading session, I noticed that his speed reading technique was much smoother, and at the next timing I noticed that his time had doubled. So I recorded the time, expressed my satisfaction to him, and moved on. Why mess with success?

Later, as we were driving south on NM 14, the Engineering Geek said: "Tonight, I've had an epiphany!" He went on to explain that he had spent years trying not to sub-vocalize while he was reading. Apparently, a teacher had told him that this was the wrong way to read! (I am endlessly amazed at the strange ideas that teachers cotton onto and refuse to let go).
Evidently, he took this to heart and began to try to read without engaging the verbal centers of his brain. From that time forward, he became a slow reader, endlessly re-reading to try to comprehend.

I explained to the Geek that readers generally either hear the words in their heads or sub-vocalize as they read. There are a few people, dyslexics among them, that do not, but that this is somewhat rare. I also explained that when people who hear the words in their heads only are practicing speed reading, often they begin to sub-vocalize again for a while, until their faster speeds become comfortable and normal. Then they go back to hearing the words in their heads. What I suspect happened to create the Engineering Geek's epiphany was that when I was explaining why we did structured discussions (adults complain about this quite a bit) I said that we want to verbalize what was just read in order to organize it in memory, and that the structure provides a framework of synaptic associations so that the information read was more easily recalled. The Engineering Geek heard that and associated it with what he'd been told about not sub-vocalizing while reading. He stopped trying to interfere with this, and he found he was comprehending what he read better.

This sparked a lively discussion where the Geek spent the better part of the drive home "data mining" my brain for what I knew about the neuroscience behind reading. I know a little from my MA in Special Ed, and I can infer more from my current studies in Neurobiology. But I began to realize that there are big gaps in my knowledge since I have not studied the topic directly.

So naturally, I began asking around. My sister Madge's son D. has dyslexia, though the schools refused to acknowledge it as such. She listened to my ideas and said, "You'd love this book I just finished..."

I can see that I am embarking on a new reading and research blitz. Thank goodness for Amazon! The UPS Orange Route driver (who knows me by name) should be winding his way up our mountain to deliver Maryanne Wolf's Proust and the Squid: The Story and Science of the Reading Brain sometime today. In anticipation I read the Epilogue of Radicals for Capitalism this morning!

Stay tuned! There is definitely more to come...

It's Not Another Shot in the Ritalin Wars

A few weeks ago a neuroimaging study was published in the Proceedings of the National Academy of Sciences. Normally, many such studies are published in various journals in science and medicine without a whole lot of fanfare. But this one had a magic phrase in the title. The phrase was one that gets ideologues everywhere very excited. The title of the study is:

Attention deficit/hyperactivity disorder is characterized by a delay in cortical maturation

The magic phrase? Attention Deficit/Hyperactivity Disorder.
In the weeks since the study was published, the press and blog worlds have been having a great deal of fun making the conclusions into another shot in the ideological "Ritalin Wars."
Some writers have claimed that AD/HD does not exist. Others have used it to claim that AD/HD is an artifact of poor diet, bad parenting, and/or curriculum reform in the public schools. Some have actually come to the conclusion that the title might suggest, that AD/HD is definitively a form of developmental delay. As we shall see, though, despite the way you might read the title, that is not the conclusion of the study.

Being a scientist myself, I decided that I would not weigh in on the conclusions until I had the chance to actually read the study. Today, as I procrastinate on a research paper I am writing, seemed like the ideal time to do so. So I went to the NY Times article from a few weeks ago and got the journal title for the article, as well as the name of the first author. Then I connected to my university library system -the joys of technology are without number!--and in five minutes I had used the e-journal finder to navigate to Highwire Press and download a pdf file copy of the study.

You can try this at home, but you may have to pay a fee to download the study. Most journals are made available to students and researchers via institutional subscriptions to publishers and databases. The article was published earlier this month in the PNAS. It is in the current issue.
The citation is:
Shaw, P. et. al. (2007). Attention deficit/hyperactivity disorder is characterized by a delay in cortical maturation. Proceedings of the National Academy of Sciences, 104 (49) 19649 - 19654.

It is a very good study. The methodology was good, the number of subjects was impressive--446 human subjects--and the conclusions made matched the data that was published. This study overall is an excellent advance in tracking brain anatomy differences between subjects that carry the diagnosis of AD/HD and those that do not.

In the abstract the researchers say:
There is controversy over the nature of the disturbance in brain development that underpins attention-deficit/hyperactivity disorder (ADHD). In particular, it is unclear whether the disorder results from a delay in brain maturation or whether it represents a complete deviation from the template of typical development.
They are telling us the purpose of the study: to get evidence that might solve the controversy in the field. But pay attention to the wording. The controversy is not whether or not the disorder results from a delay in brain maturation, but whether or not it "represents a complete deviation from the template of typical development." The question they is whether or not AD/HD can result partly from a delay in brain maturation.

The authors repeat this in different words in the introductory paragraph:
Since its earliest descriptions, there has been debate as to whether the disorder is a consequence partly of delay in brain maturation or as a complete deviation from the template of typical development.

As I have said above, the data from their work does support their hypothesis that AD/HD is "a consequence partly of delay in brain maturation." That means they have done a good study. But one study does not an etiology make. It is important for the non-scientist to get it that one does not prove or disprove a hypothesis from one study, even one so well constructed as this one. Good scientists know this, and in the discussion section of any well-written scientific report, they will report caveats and weaknesses and any possible confounding variables. This is so that, when future studies are done, they (or others) can try to fill in the gaps for the study. That's usually done by fiddling with the methodology.

This study was a well-written study by good scientists and they do point out weaknesses that might be fixed in future work. In the very beginning they point out that many studies using physiological data (this study uses anatomical data)--that is how the brain is actually working--support their hypothesis, but there are also many other studies that find "a quantitatively distinct neurophysiology, with unique architecture of the (EEG) and some highly anomylous findings in functional imaging studies, more in keeping with ADHD as a deviation from typical development." This is interesting. When I first heard of the study and heard that it was done using anatomical imaging, I wondered about what functional imaging would show. If I want, I can check it out.

Geek Alert! A question I now have is this: fMRI studies require the use of fluorescent dyes or other ways of getting the signal above ground. These are not usually done on children (for obvious reasons). So I wonder if these confounding studies are targeting an adult population with ADHD? If so, it could be that we are dealing with two very different populations. After all, adults with ADHD would be the children who did not grow out of it.

Another issue: The study was done using anatomical imaging and not functional imaging. The researchers used very good techniques to get at the maturational rate of various parts of the brain, but ultimately they were still measuing gray matter (neuron cell bodies) cortical thickness. Two questions: Are there differences between the two populations in the percentage of gray matter v. white matter (glia and myelenation)? And what about physiological differences? Do the brains work differently? I saw an fMRI study just this morning that showed differences in activation in the pre-frontal cortex (Brodman 9) for adults with ADHD (little to no activation) and typical adults.

In other words, anatomy is not the whole story here.
And to be fair, it was not the authors who claimed that it was.
That would be the press and pundits and ideologues. In other words, those who either did not bother to read the study carefully or those who have an axe to grind when it comes to issues about AD/HD.

So what did we find out from this study? We found out that part of the difference between kids with a diagnosis of ADHD and those without, is in the rate of brain maturation. Kids with AD/HD diagnoses (it was a mixed group of kids with primarily hyperactive, primarily inattentive and combined types) have brains in which the cortices mature more slowly, delayed by approximately 3 years, with a very significant p value. And we found out that in these kids, the brain development trajectory was the same for kids with and without ADHD.

But the researchers also analyzed the data for specific brain areas. And these tests showed that the trajectory of the brain development for all cortical areas was not identical. The kids with ADHD tended to have faster motor area maturation than those without. And they had slower executive function (frontal lobes!) maturation.
What does James Webb say of gifted kids? Farrari motor and dune buggy driver! It looks like the same developmental pattern is true for kids with ADHD.

This is very useful information. It is particularly useful for people who treat kids with ADHD as well as for people who teach them. It is very helpful in planning interventions to help these kids learn academically and function socially to know that their executive function maturity may be more than three years behind the average kid. As a teacher, as a researcher, and as a parent, I find this information to be extremely helpful and very interesting.

But it is not another shot in the Ritalin wars.

The authors did not say that ADHD does not exist. In fact, in their first paragraph, they define it as a neurological disorder. They describe the delayed maturation of the cortices of the brain as a "characterizing" ADHD. It is, then, a characteristic that could be used to differentiate people who have ADHD and people with other psychiatric diagnoses.

They did not say that children with ADHD should not be treated with stimulants like Ritalin. In fact, one possible confounding variable they mention is that 80% of the clinical population in the study (clinical = those with ADHD diagnoses) were being treated with stimulant medication. They do say that stimulant medication can be an effective short-acting treatment.

Finally, by calling the maturational delay a characteristic, the authors imply that there is another, more ultimate cause. They discuss this further in the last part of the discussion. The differences cannot be attibuted to intelligence or sociocultural factors because these were controlled in the design of the study. There is definite evidence that the differences are partly due to genetics because brain growth and development is controlled by molecules called neurotrophins and "polymorphisms within the brain-derived neurotrophic factor and
nerve growth-factor 3 genes have already been tentatively linked with ADHD."
A polymorphism is a difference in DNA base sequences from one individual to another.

A claim that genetics is involved in causing a neurological disorder does not mean that environment does not play a role. It is likely that something as complicated as differences in brain development is controlled by quite a few genes, that is, it is polygenic. It is also likely that some of those genes effect a number of different systems, that is, they are pleiotrophic. And of course, environment does affect gene expression--that is what proteins the genes make and when they are activated.

So that's it, folks. It is a very good study. It was done well, and as in most well-done scientific studies, it raises more questions for future work.

And the findings do not provide fuel for the ideologues among us.