About 6 percent of the children — 740 — were prescribed medication to treat ADHD between 2003 and 2009. Those in the youngest third of their classes were 50 percent more likely than their peers in the oldest third to be prescribed ADHD drugs from ages 7 to 14, the study found.

Nearly one in five high school-aged boys in the United States has been diagnosed with attention deficit hyperactivity disorder, the New York Times reports. Federal data from the Centers for Disease Control and Prevention show that 11 percent of all school-age children have a medical diagnosis of ADHD.

There are 6.4 million children ages 4 through 17 who’ve received the diagnosis at some point in their lives — a 16 percent increase since 2007 and a 53 percent rise over the past decade, the story said. About two-thirds of those currently diagnosed have prescriptions for stimulant drugs like Ritalin or Adderall, which can improve life for those with the disease, but come with risks of addiction and anxiety.

Doctors are concerned that the ADHD diagnosis is overused, the Times said, and some say the rising number of diagnoses suggests that millions may be taking the medications to calm behavior and improve school performance.

There is no single test to diagnose ADHD, according to the CDC. Psychiatrists look for patterns of inattention, hyperactivity and impulsivity before making a subjective judgment about the diagnosis.

ADHD is the most common behavioral disorder of childhood, but it affects adults, too, according to Medical News Today.

“An individual with ADHD finds it much more difficult to focus on something without being distracted," Medical News Today said. “He has greater difficulty in controlling what he is doing or saying and is less able to control how much physical activity is appropriate for a particular situation compared to somebody without ADHD. In other words, a person with ADHD is much more impulsive and restless.”

The cause of ADHD is not known, but a person’s risk of developing the disorder is higher if a close relative has it, and is more common in boys. Many scientists believe ADHD is the result of chemical imbalances in the brain

ADDitude magazine suggests that parents of children diagnosed with ADHD provide even more routine and structure than typical children need.

“Set up a morning routine for ADHD children to get out the door on time. Make sure homework happens at the same time and in the same setting daily. Do something fun to unwind before a regular bedtime,” the article said.

A predictable schedule helps kids feel safe and secure and makes daily activities manageable, resulting in a relaxed home where stronger family relationships can thrive, the ADDitude said.

Experts cited in the New York Times story offered theories to explain the sharp rise in ADHD diagnoses. Some doctors are too hasty about viewing complaints of inattention as ADHD, and advertising hype from pharmaceutical companies may be partly to blame. Parents could be part of the problem, too, if they pressure doctors for medicine to tame their children's behavior and improve their grades.

After all, kids will be kids, Harvard medical professor Jerome Groopman told the New York Times.

"There’s a tremendous push where if the kid’s behavior is thought to be quote-unquote abnormal — if they’re not sitting quietly at their desk — that’s pathological, instead of just childhood," Groopman said.