Word: adhd
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Dates: during 1990-1999
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...medical record on ADHD is said to have begun in 1902, when British pediatrician George Still published an account of 20 children in his practice who were "passionate," defiant, spiteful and lacking "inhibitory volition." Still made the then radical suggestion that bad parenting was not to blame; instead he suspected a subtle brain injury. This theory gained greater credence in the years following the 1917-18 epidemic of viral encephalitis, when doctors observed that the infection left some children with impaired attention, memory and control over their impulses. In the 1940s and '50s, the same constellation of symptoms was called...
Nobody fully understands how Ritalin and other stimulants work, nor do doctors have a very precise picture of the physiology of ADHD. Researchers generally suspect a defect in the frontal lobes of the brain, which regulate behavior. This region is rich in the neurotransmitters dopamine and norepinephrine, which are influenced by drugs like Ritalin. But the lack of a more specific explanation has led some psychologists to question whether ADHD is truly a disorder at all or merely a set of characteristics that tend to cluster together. Just because something responds to a drug doesn't mean...
...ADHD researchers counter the skeptics by pointing to a growing body of biological clues. For instance, several studies have found that people with ADHD have decreased blood flow and lower levels of electrical activity in the frontal lobes than normal adults and children. In 1990 Dr. Alan Zametkin at the National Institute of Mental Health found that in PET scans, adults with ADD showed slightly lower rates of metabolism in areas of the brain's cortex known to be involved in the control of attention, impulses and motor activity...
Zametkin's study was hailed as the long-awaited proof of the biological basis of ADD, though Zametkin himself is quite cautious. A newer study used another tool -- magnetic resonance imaging -- to compare the brains of 18 ADHD boys with those of other children and found several "very subtle" but "striking" anatomical differences, says co-author Judith Rapoport, chief of the child psychiatry branch at NIMH. Says Zametkin: "I'm absolutely convinced that this disorder has a biological basis, but just what it is we cannot...
...inherited. External factors such as birth injuries and maternal alcohol or tobacco consumption may play a role in less than 10% of cases. Suspicions that a diet high in sugar might cause hyperactivity have been discounted. But the influence of genes is unmistakable. Barkley estimates that 40% of adhd kids have a parent who has the trait and 35% have a sibling with the problem; if the sibling is an identical twin, the chances rise to between...