The number of children diagnosed with attention deficit hyperactivity disorder, or ADHD, has increased over 40% among schoolchildren, according to an eight-year study. There was an especially sharp rise among girls and Hispanics. Traditionally, boys have been far more likely to be given an ADHD diagnosis.

The George Washington University study only looks at how frequently ADHD is diagnosed. It does not offer an answer as to whether ADHD is becoming more common in children or is merely being diagnosed more often.

Though not part of the study, the question of why the condition seems to be increasing is important.

The information came from the National Survey of Children's Health, a nationally representative survey that collects information on the health of children age 17 and younger. It asked parents whether their child had been diagnosed with ADHD by a doctor or health care professional.

Between 2003 and 2011, parents' “yes” answers rose by 43% and in 2011 a total of 12% of the children in the survey were diagnosed with ADHD. If that figure holds true for the entire country, it would mean that 5.8 million children age 5 to 17 now have been diagnosed with an attention problem.

Diagnoses among girls rose from 4.3% in 2003 to 7.3% in 2011. Roughly 83% more Hispanic youths were diagnosed with ADHD over that same time period.

Children with ADHD often have trouble paying attention in class and at home, and tend to be impulsive or prone to making careless mistakes. They can also be forgetful. Without treatment, these problems can lead to all sorts of difficulties at home, school and in social situations. Adults with ADHD typically have problems in their work and social relationships.

Though not part of the study, the question of why the condition seems to be increasing is important. Some students are misdiagnosed simply because they are young or immature.

An ADHD diagnosis usually leads to a prescription for stimulant drugs such as Ritalin or even amphetamines, as well as extended time on standardized tests. While such drugs can help children (and adults) with ADHD focus and stay on task, they also have side effects, and critics worry that they may be over-prescribed. In addition, the long-term effects of the drugs used to treat ADHD have not yet been well-studied. Many doctors believe that the best treatments are multi-faceted and do not rely solely on medicating ADHD symptoms.

Since there is no single definitive test to diagnose ADHD, there can be plenty of confusion among parents over whether their child might have such a serious attention deficit. The authors suggest that parents who are concerned about their child's ability to focus or their behavior speak with a doctor before jumping to conclusions.

The study appears in the Journal of Clinical Psychiatry.