The diagnosis of ADHD is more common among the youngest students in the class: shots

According to a study published online Wednesday, the youngest children in a class are more likely to suffer from Attention Deficit Hyperactivity Disorder. In fact, their relatively hectic behavior may be due to their relative immaturity.

Scientists at Harvard University have examined how ADHD is assessed by taking advantage of a quirk in many American school systems: there is a deadline for enrollment in kindergarten on September 1st. This means that children born in August are a little under the wire, while children whose birthday is in September must wait until the next school year to register.

"You can certainly imagine a scenario in which a teacher, or a member of the school staff who evaluates them, would see two children in a different age group a year or so," says the doctor. Anupam Jena, Physician and Economist at Harvard Medical School "The difference in age between a 5-year-old and a 6-year-old is enormous."

By browsing an insurance claims database of more than 400,000 children, researchers ranked children by month of birth. And the report in the New England Journal of Medicine finds that the youngest children in the class – those born in August – were about 35% more likely to be diagnosed with ADHD and to be treated for this condition.

ADHD was diagnosed in 0.8% of children born in August, compared to 0.6% of older children born in September. Nationally, the diagnosis rates for ADHD are about 5%, but this includes children aged 2 to 17, while this study focuses on children aged 4 to 7 years.

Scientists have not found this difference in states that do not apply the September 1 registration date and they found no other health differences among children born in August in the study.

This result is important for every child who may have been diagnosed and treated inappropriately. "You want to be careful not to take this medicine to a young child," says Jena.

But the effect of registration explains that a small proportion of ADHD. For the youngest – children born in August – Jena says that maybe one in four diagnoses might be inappropriate.

"Teachers, counselors, school directors – these people should be aware of this possibility," says Jena. School staff members are most likely to raise the flag of ADHD and suggest parents to have their children seen by a pediatrician.

Jeffrey Newcorn, a psychiatrist and pediatrician at the head of the ADHD and Learning Disorders Division at Mount Sinai Medical Center in New York, said the study was fueling scientific discussions about ADHD. But, he says, "I would be very careful to read this as if the children were misdiagnosed."

You may be more likely to identify ADHD in the youngest children in their class, he says, but perhaps this is nothing more than an early diagnosis, which would have produced in a year or two anyway.

Several other studies have suggested that ADHD is more likely to be diagnosed in children who are among the youngest of their classes.

"The present study is convincing because of the size of its sample and the use of diagnostic registers, rather than a subjective reminder," says Stephen Hinshaw, professor of psychology, a long-time researcher on ADHD at the University of California at Berkeley, in an email. .

These findings highlight weaknesses in the identification of ADHD, writes Hinshaw in an email. "Indeed, many childhood problems can be similar to ADHD: trauma, overcrowded classrooms, medical problems (eg convulsions) or other psychiatric problems (eg, anxiety, depression). So, a brief visit to the office to the task! "

The results that rely on health insurance data lack important details.

"We really do not know much about the" why "and" how "of these results," says Meredith Bergey, a sociologist at Villanova University. It is difficult to understand how these diagnoses were made, simply based on the data from the insurance registers.

ADHD is not a simple diagnosis, like an ear infection. Bergey therefore argues that the process should be more deliberative. "What if the teacher was there with the parent and the doctors?" she asks. This would better inform the diagnosis and take into account potentially important factors such as the age of the child.

You can contact NPR Scientific Correspondent Richard Harris at [email protected].