Add
ADD was first identified and studied in the early 1900's, although it wasn't called ADD back then. After World War I, researchers noted that children who had contracted encephalitis displayed a high incidence of hyperactivity, impulsivity, and conduct disorders. And in the 1940's, some soldiers who had experienced brain injuries were found to have behavioral disorders.1 It seemed clear that brain damage could cause hyperactivity. Other forms of brain insult have since been identified as causes of hyperactivity, including exposure to lead and other environmental toxins, as well as fetal exposure to drugs and alcohol.
Once brain damage was identified as a cause of hyperactivity in certain patients, researchers assumed that all hyperactivity was caused by brain damage, even when no brain damage could be identified. That's why ADD was once called "minimal brain dysfunction." This is an important point to understand. It is because of this early association of brain injury and hyperactivity that ADD traits are still assumed by many to reflect a brain disorder. Researchers made a giant leap in logic: Because brain injury can lead to hyperactivity, they believed that all hyperactivity was caused by brain injury. We now know this is not true. In fact, hyperactivity is also associated with giftedness, but obviously we cannot say that all hyperactive children are gifted any more than we can say all hyperactive children have suffered brain injury.
More recent studies have shown that ADD is largely genetic. That is, it runs in families. This has lead some ADD researchers, notably Russell Barkley, to assume that our population is experiencing large scale random genetic mutations, a rather ridiculous notion for anyone familiar with population genetics. Anytime more than one percent of the population carries a gene, geneticists rule out random mutations under the belief that the gene has been actively selected for. For example, the...
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