Younger school entry could set stage for ADHD diagnosis

  • Nov. 28, 2018 4:01 p.m.

The youngest children in kindergarten are more likely to be diagnosed with attention deficit hyperactivity disorder in early grades, a study shows, an intriguing finding for parents on the fence about when to start their child in school.

The study found younger students, especially boys, are also more likely to be started on medications for ADHD and kept on the drugs longer than the oldest children. The medications are generally safe, but can have harmful side effects.

“Doctors and therapists need to factor that into their decision-making,” said study co-author Dr. Anupam Jena of Harvard Medical School. They should ask, “Does he really have ADHD, or is it because he needs six more months to mature? That extra year makes a big difference.”

About 6 million U.S. children and teenagers have been diagnosed with ADHD, which causes inattention, hyperactivity and impulsivity. The rate of diagnosis is climbing.

The study, published Wednesday by the New England Journal of Medicine, stemmed from a lunchroom conversation about “kindergarten redshirting” for a co-author’s son. The term is borrowed from athletics and means waiting a year to give a child time to mature.

“The parents were thinking about whether or not to hold their child back an additional year,” Jena recalled. That led the researchers to ask, “What happens to kids who are in the same class who are perceived to be different?”

They used insurance claims to compare more than 71,000 students with August and September birthdays in 18 states with Sept. 1 cutoffs. A child who turns 5 before Sept. 1 can start kindergarten. If not, the child waits until the next year. An August birthday can mean a child is the youngest in class while those born in September are the oldest.

Overall, from birth to the first few years of school, the number of children diagnosed with ADHD was low. The researchers calculated that the rate of ADHD diagnosis was a third higher in August-born kids than in September-born kids, based on 309 cases among about 36,300 with August birthdays and 225 cases among about 35,300 born in September.

There was no group difference before age 4 it showed up after school enrolment.

The researchers also looked at asthma, diabetes and obesity rates and found they were the same for the August and September babies. And no other month-to-month comparison showed a sharp difference in ADHD.

Finally, using insurance data for more than 400,000 children in all 50 states, the researchers looked at states that don’t use a Sept. 1 cutoff and the effect disappeared.

“They did so many careful (checks) to make sure of their findings. It was really striking it was so consistent,” said Dr. William Cooper, a pediatrics and health policy professor at Vanderbilt University in Nashville, who wasn’t involved in the research.

Cooper said younger children can have more trouble paying attention, sitting still and controlling their impulses. Compared to other kids, they may look like they have ADHD.

The study didn’t evaluate whether the children were diagnosed appropriately. The August-September difference could be a reflection of spotting actual cases of ADHD earlier in the August-born kids because of their early start to school, said Dr. Jonathan Posner, an associate professor of psychiatry at Columbia University Medical Center in New York.

On the other hand, since there’s no lab test for ADHD, doctors rely on subjective observations from parents and teachers. A younger student may simply need time to catch up, but his immature behaviour looks like ADHD and raises a teacher’s concern, said Posner, who wasn’t involved in the study.

“The information we receive about a child has to be interpreted within a developmental context,” Posner said. “A 4-year-old isn’t going to respond as well to academic challenges as a 5-year-old.”

ADHD stimulant medications are generally considered safe, Posner said, but some children have side effects such as lowered appetite, sleep troubles and afternoon rebounds of hyperactivity.

The study didn’t include kids covered by Medicaid, the government insurance program that serves 35 million low-income children. Other research has shown children on Medicaid are more likely to be diagnosed with ADHD, which may account for the low rates of diagnosis in the new study, Jena said.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Health Minister Tyler Shandro and Dr. Deena Hinshaw, the chief medical officer of health, receive flu shot. Photo via Government of Alberta
COVID cases climb in central zone, Red Deer

The total number of active COVID-19 cases in the province reached 3,138… Continue reading

Many rural municipalities were concerned about a proposed reduction to their industrial revenues, but Alberta’s municipal affairs minister has come up with an alternative solution. (Photo contributed)
Energy industry support won’t injure municipalities

Creating new wells or pipelines would result in a three year ‘tax holiday’

Conservative Leader Erin O’Toole and Premier Jason Kenney participated in a livestream on Oct. 17, 2020. (File photo by THE CANADIAN PRESS)
UCP members pass resolution at AGM calling for privately funded health care option

EDMONTON — Members of Alberta’s governing United Conservative Party have narrowly endorsed… Continue reading

“We weren’t sure what to expect with just doing the 50/50. We have been positively surprised with sales so far,” says Craig Fleming, co-chair of the Red Deer Kinsmen Club’s raffle. (Photo by SUSAN ZIELINSKI/Advocate staff)
Non-profits put their money on 50/50 draws

COVID impacts fundraising events

Student taking a math test. (Pixabay photo)
David Marsden: Students need more testing, not less

Testing has been central to Alberta’s response to the COVID-19 pandemic. It’s… Continue reading

Gillian Robertson celebrates her win over Sarah Frota during UFC 240, in Edmonton, Saturday, July 27, 2019. Robertson used her superior grappling skills to dominate Brazil's Poliano Botelho en route to a unanimous decision win Saturday night on a UFC Fight Night card. THE CANADIAN PRESS/Jason Franson
Canadian Gillian (The Savage) Robertson dominates in UFC decision win in Abu Dhabi

Canadian Gillian (The Savage) Robertson dominates in UFC decision win in Abu Dhabi

Forge FC head coach Bobby Smyrniotis, right, hugs captain Kyle Bekker following their victory in the Canadian Premier League soccer final against Cavalry FC in Calgary, Saturday, Nov. 2, 2019. A month after winning the Island Games in Charlottetown, Hamilton-based Forge FC is back on the move. THE CANADIAN PRESS/Jeff McIntosh
CPL champion Forge FC off to El Salvador for CONCACAF League preliminary-round match

CPL champion Forge FC off to El Salvador for CONCACAF League preliminary-round match

Course workers prepare the landing area at the ski jump venue in Whistler Olympic Park in Whistler, B.C. Friday, Feb. 5, 2010. THE CANADIAN PRESS/Jonathan Hayward
Next generation of Canadian ski talent sets sights on Whistler, B.C., in 2023

Next generation of Canadian ski talent sets sights on Whistler, B.C., in 2023

Mighty Heart is held by groom Siobhan Brown in his stall at trainer Josie Carroll's stable at Woodbine Racetrack, in Toronto, Thursday, Oct. 15, 2020. The one eyed horse, will run in the $400,000 Breeders' Stakes on October 24, attempting to become Canada's first horse to win the Triple Crown since Wando in 2003. THE CANADIAN PRESS/Chris Young
Rain could present big challenge in Mighty Heart’s quest to capture Triple Crown

Rain could present big challenge in Mighty Heart’s quest to capture Triple Crown

Veteran sniper Evgenii Dadonov excited to join Senators: ‘It’s a perfect fit’

Veteran sniper Evgenii Dadonov excited to join Senators: ‘It’s a perfect fit’

Tampa Bay Buccaneers running back Ronald Jones II (27) gets pushed out of bund by Green Bay Packers free safety Darnell Savage (26) during the second half of an NFL football game Sunday, Oct. 18, 2020, in Tampa, Fla. (AP Photo/Mark LoMoglio)
Packers seek to bounce back after embarrassing defeat

Packers seek to bounce back after embarrassing defeat

World junior hockey championship opens on Christmas Day for first time since 2005

World junior hockey championship opens on Christmas Day for first time since 2005

Most Read