Thursday, March 30, 2006

The developing brain: some big surprises

This is quite surprising. The human brain changes extensively between birth and adolescence (that we knew), but what's interesting is that it the pattern of changes is highly variable. Not everyone's brain follows the same developmental path.
Science & Technology at Scientific Smart Kids Found to Undergo Delayed Brain Development

... Rapoport and her colleagues at NIMH and McGill University followed 307 children of varying ages as they grew up, scanning them with an MRI machine periodically. They then compared such measures as brain volume with the results of a standard IQ test. Contrary to popular perception, the brightest kids did not necessarily have the largest brains.

They did, however, exhibit a distinctive pattern of brain development. Whereas an average child's cortex thickness peaked around age eight, the smartest children experienced thickening of the cortex until early adolescence. In all of the subjects, the cortex waned during adolescence, perhaps due to the pruning of neurons as the brain becomes more efficient, the researchers speculate.

Complicating the picture, however, relatively intelligent children--smarter than average but not the smartest--followed roughly the same development pattern as their more typical peers. And in the smartest kids the cortex shrank more than most during adolescence, in some cases dropping them below their relatively intelligent peers.

Although such intelligence seems to be genetic, the child-rearing environment may play an even more critical role, the researchers stress. Studies in rats have shown that their cortex thickness depends on richness of experience. [jf: I think this is misleading. The experimental rats they refer to had very limited environments, any reasonably decent human environment may be more than rich enough to make genetics the rate limiting step.]
It will be very interesting to see the results of similar studies performed in autistic children, particularly if we study not only pre-adolescents but also changes extending into the 20s. I have long wondered what the true natural history of so-called "high functioning autism" really is ...

Tuesday, March 14, 2006

Redefining mental retardation and autism - the revolution ahead

I've been known to protest that medical progress is much slower than popularly imagined. It's been over seven years since I was in active practice, yet current textbooks are often very familiar. Some of the meds are new, but the newest ones don't always last. Much of the therapy is basically unchanged.

But there are revolutions brewing.

The intersection of high resolution neuro-imaging and genetic analysis is dramatically changing our understanding of disorders sometimes known as 'mental retardation':
A developmental and genetic classification for malformations of cortical development -- Barkovich et al. 65 (12): 1873 -- Neurology

Increasing recognition of malformations of cortical development and continuing improvements in imaging techniques, molecular biologic techniques, and knowledge of mechanisms of brain development have resulted in continual improvement of the understanding of these disorders. The authors propose a revised classification based on the stage of development (cell proliferation, neuronal migration, cortical organization) at which cortical development was first affected. The categories are based on known developmental steps, known pathologic features, known genetics (when possible), and, when necessary, neuroimaging features. In those cases in which the precise developmental and genetic features are uncertain, classification is based on known relationships among the genetics, pathologic features, and neuroimaging features. The major change since the prior classification has been a shift to using genotype, rather than phenotype, as the basis for classifying disorders wherever the genotype–phenotype relationship is adequately understood. Other substantial changes include more detailed classification of congenital microcephalies, particularly those in which the genes have been mapped or identified, and revised classification of congenital muscular dystrophies and polymicrogyrias. Information on genetic testing is also included. This classification allows a better conceptual understanding of the disorders, and the use of neuroimaging characteristics allows it to be applied to all patients without necessitating brain biopsy, as in pathology-based classifications.
This very specialized article is not for the layperson; it's really written for the pediatric neurologist. Beneath the jargon, however, are some tectonic shifts in the definition of developmental disorders. It's a migration from external appearances (pre-1990 and still the world in which most of us live) beyond imaging studies (1990-2001, cutting edge yet) to the intersection of genes and environment (2005 and beyond).

The word "autism" doesn't appear in the paper, but that's only a matter of time. We are about to change the way we think of disorders of the developing mind and brain, and many of our labels are going to go away. In the new world we'll begin to make sensible statements about prognosis and to design studies of therapy that can be truly meaningful. This is good.

PS. See also: Asperger's a vague diagnostic concept.

Monday, March 06, 2006

When ADHD is not a disorder: the adaptive advantages of spontaneity

We have often thought our son would have done well laboring on a farm, or scouting ahead of a tribe spying for enemies, predators, and prey. Alas, his superior visual processing and restless activity are ill-suited to today's world. In our world his ADHD and other traits mean he is profoundly disabled.

Paul Steinberg writes about how a set of traits that are adaptive in on setting, can be maladaptive in another...

Attention Surplus? Re-examining a Disorder - New York Times:
March 7, 2006

... Every generation likes to believe that it is witnessing the most dramatic epoch in history. In the case of the current Western world, that belief may indeed be accurate, particularly in light of the striking changes of the last 30 years.

As the business writer and consultant Peter Drucker pointed out, most people in the United States, Japan and parts of Europe are "knowledge workers." We live in an information age, in a knowledge-based economy.

For those of us who have "attention-surplus disorder" — a term coined by Dr. Ned Hallowell, a psychiatrist in Boston who has A.D.H.D. — this knowledge-based economy has been a godsend. We thrive.

But attention disorder cases, up to 5 to 15 percent of the population, are at a distinct disadvantage. What once conferred certain advantages in a hunter-gatherer era, in an agrarian age or even in an industrial age is now a potentially horrific character flaw, making people feel stupid or lazy and irresponsible, when in fact neither description is apt.

The term attention-deficit disorder turns out to be a misnomer. Most people who have it actually have remarkably good attention spans as long as they are doing activities that they enjoy or find stimulating. As Martha B. Denckla of the Kennedy Krieger Institute in Baltimore has noted, we should probably be calling the condition something like "intention-inhibition disorder," because it is a condition in which one's best intentions — say, reading 50 pages in a dense textbook or writing a 10-page paper in a timely fashion — go awry.

Essentially, A.D.H.D. is a problem dealing with the menial work of daily life, the tedium involved in many school situations and 9-to-5 jobs.

Another hallmark, impulsivity, or its more positive variant, spontaneity, appears to be a vestige from lower animals forced to survive in the wild. Wild animals cannot survive without an extraordinary ability to react. If predators lurk, they need to act quickly...

... For those with attention disorder who wish to be full participants in a knowledge-based world, medications equalize their opportunities. The drugs should and can be used only as needed in the context of dealing with the tedium of school or the drab paperwork of some jobs.

Cardiologists, biostatisticians and consumer advocates may clamor, appropriately or inappropriately, to reduce the use of the medications. But unless we go back to the caveman world, some people will find the drugs increasingly necessary to succeed as knowledge workers in a drastically transformed modern world.

Paul Steinberg is a psychiatrist and writer in Washington.
Paul's primary agenda is to justify the use of Ritalin despite its new 'black box warning'. Even so, it's nice to see some attention given to how a set of traits can become a disorder -- depending on the context.

As to that black-box warning, it should focus minds prior to prescribing stimulant meds of all classes. That's not bad, even though I rather suspect we'll find caffeine has similar problems. In our case, however, we didn't blink an eye. When you're receiving incoming fire, sometimes you drive without a seat belt.

Thursday, March 02, 2006

No more adwords

The Google Adword links that have been showing up lately have been largely for sites that exploit vulnerable families with false claims and toxic treatments.

They're gone.