Aug. 17, 2010 -- Many children who are disruptive in school classrooms are misdiagnosed with Attention-Deficit Hyperactivity Disorder, when all they really are ... are young, according to a new study.
Michigan State University researchers found that as many as 1 million U.S. school kids may have been misdiagnosed with ADHD because they are the youngest and -- therefore, typically most immature -- students in class.
"If a child is behaving poorly, if he's inattentive, if he can't sit still, it may simply be because he's 5 and the other kids are 6," said Todd Elder, assistant professor of economics at Michigan State in Lansing.
His findings are to be published in the Journal of Health Economics.
Three to 7 percent of U.S. school-age children suffer from ADHD, according to the Centers for Disease Control and Prevention in Atlanta. As of 2006, 4.5 million children, ages 5 to 17, had been diagnosed with the disorder.
But there are no blood tests or other neurological markers for ADHD, researcher Elder said. Experts disagree on the disorder's prevalence among children.
Elder's study examined a data base of 12,000 children, measuring the difference in ADHD diagnosis between the youngest and oldest children of kindergarten age. The statistics showed the youngest were 60 percent more likely to be diagnosed with ADHD than the oldest, he said.
He also found that when students reached the fifth and eighth grades, the youngest were more often prescribed stimulants than their older classmates.
"Many ADHD diagnoses may be driven by teachers' perceptions of poor behavior among the youngest children in a kindergarten classroom," he said.
"But these 'symptoms' may merely reflect emotional or intellectual immaturity among the youngest students."
For example, Michigan children born Dec. 1, the state's kindergarten-eligibility cutoff date, were diagnosed with ADHD at a much higher rate than children born Dec. 2, who had to enroll a year later and, thus, were the oldest in their class.
Measure by Age, Not Grade-Level
Likewise, the Dec. 1 kids were the youngest in their class. Thus, Elder said, the students were a single day apart in age but were assessed differently because they were compared against classmate of a different age set.
Children should be evaluated for behavioral problems based on their ages, he said, not their grade-levels.