ADHD is more likely to be diagnosed in younger children in the classroom.

The rate of ADHD diagnoses in children has increased dramatically over the past 20 years. In 2016 alone, over 5% of American children were actively treated with drugs to treat ADHD. According to the experts, the increase is fueled by a combination of factors, including greater recognition of the disease, a real increase in the incidence of the disease and, in some cases, a misdiagnosis.

In a new study by the Harvard Gazette, scientists have associated a positive relationship between school-leaving age and children's cognitive development. The study suggests that the date of birth of the child exposes him to a risk of misdiagnosis of ADHD, at least in children born in August entering school in states where registration is interrupted at school. expected date of birth on 1 September.

The results of the new study underline the idea that, at least in a sub-group of primary school children, diagnosis can be a factor in early schooling. Meanwhile, it is possible that a large number of children are over-diagnosed and over-treated for ADHD. They happen to be relatively immature compared to their older peers in the early years of primary school.

Lead author of the study, Timothy Layton, said, "Most states have arbitrary birth date thresholds that determine the class in which a child will be placed and the time when he or she can start # 39; school. In states where the deadline is September 1st, a child born on August 31st will be almost a year younger on the first day of school than a classmate born on September 1st. "

"At this age, the youngest child may have more difficulty sitting still and concentrating for extended periods in the classroom. This additional agitation can lead to a medical referral followed by a diagnosis and treatment for ADHD. "

Anupam Jena, lead author of the study, said, "As children grow older, small age differences equalize and dissipate over time, but on the behavioral level, the difference between a 6 year old and a 7 year old could be quite pronounced. Normal behavior may seem abnormal compared to the child's peer group. "

Scientists collected data from a large insurance database and compared the difference in diagnosis of ADHD by month of birth – August compared to September. They followed nearly 407,000 primary schoolchildren born between 2007 and 2009 until the end of 2015.

In states that use September 1 as the cut-off date for schooling, children born in August are 30% more likely to be diagnosed with ADHD than children born in September, according to the analysis. No such differences were observed between children born in August and September in states with deadlines other than September 1.

When the investigators looked only at the treatment of ADHD, the difference was also significant – 53 students out of 10,000 born in August received treatment for ADHD, compared to 40 out of 10,000 for those born in September.

Research has shown wide variations in the diagnosis and treatment of ADHD in different regions of US ADHD treatment and diagnosis rates have also increased dramatically over the past 20 years. In 2016 alone, more than 5% of all American children were taking medication for ADHD, the authors noted. All of these factors have fueled concerns about overdiagnosis and over treatment of ADHD.

Jena said, "The reasons for the increase in the incidence of ADHD are complex and multifactorial. Arbitrary deadlines are probably just one of the many variables at the root of this phenomenon, he added. In recent years, many states have adopted measures that hold schools accountable for identifying ADHD and encourage educators to refer any child with symptoms suggestive of ADHD for the purpose of medical evaluation.

"The diagnosis of this disease is not only related to the symptoms, but to the context. The relative age of children in the classroom, laws and regulations, as well as other circumstances, come together.

"It is important to consider all of these factors before making a diagnosis and prescribing a treatment. The age of the child in relation to peers at the same level should be taken into account and the reasons for this referral examined carefully. "

The results are published November 28 in the New England Journal of Medicine.