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PHILADELPHIA CBS) — A growing number of children are being diagnosed with ADHD — Attention-Deficit Hyperactivity Disorder — and it’s one of the most common mental disorders affecting children.

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However, doctors say it can usually be effectively treated, especially when accurately diagnosed early.

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The number of children diagnosed with the disorder in the United States has sharply increased over the past 20 years.

Researchers say part of the reason why ADHD is becoming more common is that doctors now have better ways to diagnose and treat the disorder.

“Whenever there’s a better treatment for diagnosis, we see more of it because people are more willing to give the diagnosis now that they know there’s something that they can do,” explains Dr. Veena Ahuja of the Cleveland Clinic Children’s Hospital.

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The study looked at data on the number of children diagnosed with ADHD between 1997 and 2016. The rates increased from 6 percent to 10 percent.

Researchers found that it increased in both boys and girls. Children with ADHD can be hyperactive, impulsive, and have trouble focusing.

“What I will tell families a lot of times is that knowledge is power. The symptoms are there whether you give it the name or not. If we name it and describe it, then we can get programs in place to help,” says Dr. Ahuja.

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Doctors say that it’s important for parents to know that some ADHD symptoms can change over time and that children who struggle with hyperactivity when they’re younger usually have fewer problems when they get into high school.

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Doctors say several things can increase the risk for ADHD, including genetics, a preterm birth, and smoking during pregnancy.