Walk into any American high school and nearly one in five boys in the hallways will have a diagnosis of attention-deficit hyperactivity disorder. According to the Centers of Disease Control and Prevention, 11% of all American children ages 4 to 17—over six million—have ADHD, a 16% increase since 2007. When you consider that in Britain roughly 3% of children have been similarly diagnosed, the figure is even more startling. Now comes worse news: In the U.S., being told that you have ADHD—and thus receiving some variety of amphetamine to treat it—has become more likely.

Last month, the American Psychiatric Association released the fifth edition of its Diagnostic and Statistical Manual of Mental Disorders—the bible of mental health—Symptoms of ADHD remain the same in the new edition: The difference is that in the previous version of the manual, the first symptoms of ADHD needed to be evident by age 7 for a diagnosis to be made. In DSM-5, if the symptoms turn up anytime before age 12, the ADHD diagnosis can be made.

Even before DSM-5, doctors were already on track to prescribe enough stimulants this year for each American man, woman and child to receive the equivalent of 130 mg of amphetamine (about 40 five-mg pills of Adderall) and an even greater amount of the very similar drug Ritalin. In this era of excessive prescribing, we seem to have forgotten the cautionary history of amphetamines in America—a history that shows how overprescribing stimulants leads to widespread dependence and addiction.

Since their introduction by the pharmaceutical company Smith, Kline & French in 1937, amphetamines have been prescribed for maladies that had more to do with societal expectations than genuine mental illness.

By 1969, doctors were prescribing the equivalent of 120 mg of amphetamine for each American—a high-water mark of per-capita consumption we are only now about to surpass. By then, the addictive potential of prescription stimulants had attracted intense scientific and public scrutiny as evidence grew that many patients were becoming dependent on the drugs. Thirty percent of patients in one study conducted in New York state admitted to using their medications recreationally.

In 1968, the National Academy of Sciences organized an authoritative investigation into the stimulants' true benefits and risks. The consensus: These drugs had limited efficacy and real harms. Medical experts discouraged the use of stimulants for both depression and obesity, but the warnings had little effect on doctors' prescribing habits until the Controlled Substances Act of 1971 mandated that stimulants be placed in a tightly controlled category of medications.

But by the 1990s, experts and advocacy groups for ADHD, some funded by pharmaceutical companies, began to argue that stimulants did not lead to addiction when treating children for the disorder, and that the stimulants actually decreased the risk of future drug abuse.

The problem with this reassuring message is that it was based on flimsy evidence.

Three months ago, the only randomized trial to study future substance abuse by ADHD kids refuted the notion that stimulants, when taken in childhood, have a protective effect.

Stimulants can certainly benefit some young children with truly disabling ADHD. However, history has already taught us that overprescribing stimulants to millions of Americans leads to dependence, addiction and overdose. By medicating children for wiggling in their chairs, losing their homework and shouting out answers, we are not teaching them vital coping skills to manage their behavior. Instead, we are teaching them to take a pill. One day, we'll look back and wonder: Why did we do this? Again.

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