In some states, this birth month is linked to higher rates of ADHD diagnosis, study says

5:00 PM EST November 28, 2018

In US states where children must turn 5 by September 1 in order to start kindergarten that year, children born in August, just before the cutoff, are more likely to be diagnosed with and treated for ADHD, according to a study published Wednesday in the New England Journal of Medicine.

The study looked at 407,846 US children born between 2007 and 2009 to see how many diagnoses of ADHD occurred in relation to the child's month of birth.

Researchers found that there were more diagnoses for children born in August and then found it was true only in states that have a September 1 cutoff date to start kindergarten, according to Timothy Layton, lead author of the study. That means the August-born children would be among the youngest in their classrooms, sometimes nearly a year younger than other classmates.

"We saw nothing for any of the pairs of months apart from August to September, where we saw this big difference," said Layton, an assistant professor of health care policy at Harvard Medical School. "We saw that this was only in states that had a September 1 cutoff. There was nothing in states that didn't have that."

According to the Education Commission of the States, which the researchers used as their source, there are 21 states with this cutoff date, including Texas, Arizona and Illinois. The remaining 29 states and the District of Columbia have a range of enrollment cutoff dates, including December 2 in California and as late as January 1 in Vermont.

Layton and his co-authors found that the rate of children with August birthdays who were diagnosed with ADHD was 34% higher than those born in September. Among the children born in August, 85.1 children per 10,000 had ADHD diagnoses, compared with just 63.6 per 10,000 born in September.

Children born in August also had a 32% higher rate of treatment for the condition than those born in September.

ADHD, or attention deficit hyperactivity disorder, is one of the most common neurodevelopmental disorders in children, according to the US Centers for Disease Control and Prevention. Symptoms include trouble paying attention, being overly active and trouble controlling impulsive behaviors.

In 2016, approximately 9.4% US children — 6.1 million — between the ages of 2 and 17 had been diagnosed with ADHD at one point in their lives, the CDC said. About 3.3 million of these children were 12 to 17 years old, 2.4 million were 6 to 11, and 388,000 were 2 to 5, the CDC said.

Some symptoms are normal behavior for children, but those with ADHD might not outgrow them. The symptoms can be severe and can cause difficulty at school, at home or with friends, the CDC said….

https://www.cnn.com/2018/11/28/health/adhd-diagnosis-august-kindergarten-study/index.html