Delayed Pain

Delayed Pain
A new study finds enduring effects from early brain trauma

Craig Bennett, squirming out of his mother's grip and racing across the street, was 4 when the drunken driver hit him. He landed some 30 feet away, unconscious, with his shoes knocked off his feet and the swelling in his brain growing. He died three times on the way to Parkland Memorial Hospital.

Craig lapsed into a coma after the doctors repaired his ruptured colon and eased the pressure from his swollen brain. Three weeks later, in early February 1993, Craig woke up. But he woke up without knowing how to eat, dress himself or speak. Three months after that, still in a daze, still unable to talk, his mother, Adelita Avila, took him home in a wheelchair, in diapers.

"Be prepared," hospital personnel told Avila. "This is the way Craig may function for the rest of his life."

But it wasn't. Once home, Craig recognized familiar objects, and, slowly, his condition improved.

One day, Avila received a letter from the Center for Brain Health at the University of Texas at Dallas. Doctors and academics there were studying children with brain trauma, following their progress for much longer than any other study had. Avila agreed to participate.

Today, Craig is one of the roughly 850 kids the Center for Brain Health, led by Dr. Sandra Chapman, has tracked. And what Chapman has found challenges 70 years of medical thinking.

What's new is not that Craig, within a year of his accident, regained all the cognitive and mechanical functions he'd lost--science had always thought the earlier the brain injury, the more likely the recovery. What's new is what happened after that, for Craig and the 850 kids Chapman has studied: 10, sometimes 15 years later, impulsive, even violent behavior where before there was none; a decline in school performance; an inability to make sound judgments.

What's causing these erratic behaviors? The onset of puberty and the ever-changing teenage brain.

That the teenage brain is not fully developed is itself a novel discovery. Five years ago, even, the medical community thought the brain was hard-wired for life by age 12. But because of experts like Dr. Chapman, whose work contributes heavily to the recent findings on the teenage brain, the American Medical Association last week made a plea to the Supreme Court, arguing that a Missouri teen who murdered a 46-year-old truck driver should get a life sentence instead of the death penalty. The AMA says that at the time of the murder, the 17-year-old's brain wasn't fully developed.

But back to Dr. Chapman. Since medical school, she'd been interested in following children with brain injuries. Seventeen years ago she started her research with grants from the National Institute of Health, tracking 200 kids at a time, checking in with each every six months, taking on more kids when their parents consented, testing and detailing all their developments until trends emerged.

Most of the kids she followed were injured in car accidents. Much of the damage was found in the kids' frontal lobes, or prefrontal cortex, the area of the brain responsible for impulse control and abstract reasoning.

Time and again, Chapman and her collaborators would watch as children made miraculous recoveries in the year after their injuries. And then, as puberty hit, parents would report sudden, erratic behavior and poor grades.

Puberty, it turns out, is when the prefrontal cortex matures. To prove it, Dr. Jay Giedd at the National Institute of Mental Health scanned certain children's brains with an MRI every two years to show how the frontal lobes develop even into one's mid-20s.

Abigail Baird, a development neuroscientist at Dartmouth University, showed teenagers pictures of faces in different states of emotion. The adults tested in Baird's study were able to identify a fearful face as a fearful face, or a surprised face as a surprised faced. The teenagers couldn't do that. Mature frontal lobes are known for differentiating between emotional expressions.

As the evidence mounted, a new theory arose: Teenage brains undergo a biological maturation that is second only to that of infancy. As the AMA brief before the Supreme Court said last week: "Scientists can now demonstrate that adolescents are immature not only to the observer's naked eye but in the very fibers of their brains." And this is for the normal kids.

For the children with frontal-lobe brain injuries, the teenage years mean, to some extent, stagnation in the prefrontal cortex. They act more impulsive, at times more violent, than their non-injured peers. And they struggle more with abstract questions: Dr. Chapman published a study last year that showed an inability among brain-injured children to grasp important points from a story they read, or understand the story's gist, whereas children in the control group were able to decipher the story's theme.

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