Volume 16, Number 2
No Self Control?
ADHD mirrors an immature brain.
And in replying, she called on more than 30 years of studies on how the brain functions in "kids who are having trouble in school but who have a normal or even robust IQ."
A few weeks earlier, Denckla had given Jason a neurological exam. She'd also asked simple things of him: to walk down a hallway on his heels and the sides of his feet, to tap the thumb of one hand, sequentially, with the fingers. And then she knew. His problem, at its core, was neither social nor psychiatric.
Beginning
her career studying dyslexia, Denckla became a household name in the field
of learning disabilities. She also set naming vocabulary milestones and
helped lay baselines for motor development in children: "It's amazing. No
studies existed in the 1960s on what normal children were like-nothing even
resembling charts of height and weight during development!"That savviness to norms gave Denckla perspective. "For years I'd seen children with learning disabilities. Yet you couldn't help but notice other troubles. Motor differences. Attentional issues. You'd see bits of each mixed together, often with an overlay of psychological problems." So Denckla broadened her focus to include all this, sensing that underlying biology demanded it.
Around that time, in the early 1980s, neuroscientists had "discovered" the cognitive brain, with its wiring for fear, pleasure and, notably, attention. The latter moved clinicians to adopt the phrase, attention deficit hyperactivity disorder (ADHD), a narrower diagnosis that hinted at flaws in brain circuitry rather than a more general brain problem.
With a practiced eye, Denckla studied ADHD children and saw tell-tale motor differences typical of basic brain immaturity. "Go to a nursery school, say 'walk on your heels,' and 100 percent of the children also 'walk' their hands. At that age, the motor cortex doesn't control the feet elegantly enough, and stimulation overflows to the hands. Tongues stick out when little ones tie their shoes."
But what's normal in nursery school signals problems in teenagers. By Jason's age, Denckla says, "motor control should be perfect-no mirroring, no overflow."
Clues as to what might be happening in the brain came from an unusual source. For a decade Denckla and colleagues were drawn to the single-gene diseases neurofibromatosis 1, Tourette syndrome and Fragile X in girls because, oddly enough, many children with those disorders also meet criteria for ADHD.
Then neuroimaging revealed key brain areas and circuits sufferers had in common with ADHD, notably the fronto-striatal and fronto-cerebellar pathways. Recent work with KKI's Stewart Mostofsky, M.D., for example, shows these brain areas to be smaller in children with ADHD.
And their role? "Along with motor control, they're the 'agenda areas' you use for planning, organizing," says Denckla. "They're for executive functions, the I-shouldn't-have-to- remind-you-about-this, you're-in-middle-school-now tissue."
Notably, the circuits and centers for motor control and executive function don't overlap but are developmentally similar, she says. "Like smoke and fire, the state of one informs about the other." Jason's hand motions, in short, tattled on his brain development. "It's a sign, a lab test for maturity of the frontal cortex that's more sensitive than any MRI," says Denckla.
"Our take on this is that everybody has something they're bad at. Most of us cope. But some kids with, say, a reading problem, have an additional lack of brain maturity that keeps them from finding their own salvation. That lack both stems from and characterizes ADHD."
So Denckla explained: "You see problems from the boy's home. Who wouldn't have emotional issues from disappointed parents and remonstrating teachers? But there's a biological substrate.
"Don't oversimplify his problem. Don't just send him to the counselor. Realize that what lies beneath it all is the issue of Jason's brain equipment. Work with that. Give him structure. Give him proactive support. Engineer his environment for success. And don't give up.
Dr. Denckla's primary appointment is with The Kennedy Krieger Institute.