Updated 20 September 2019

ADHD may only appear in early adulthood

Looking at long-term data from 2,200 British twins, researchers found that close to 70 percent of those diagnosed with ADHD as young adults did not have the disorder when they were children.

A new British study suggests that attention-deficient hyperactivity disorder (ADHD) may often develop in the young adult years.

High levels of symptoms

Researchers at Kings College London looked at long-term data from 2,200 British twins. They found that close to 70 percent of those diagnosed with ADHD as young adults did not have the disorder when they were children.

People with this "late-onset" ADHD also tended to have high levels of symptoms, impairment and other mental health disorders, according to the study.

A Brazilian study in the same issue of the journal also found that a large percentage of adults with ADHD did not have the condition in childhood, and the British and Brazilian studies support the findings of a prior New Zealand study.

Read: ADHD may affect boys and girls in different ways

"Our research sheds new light on the development and onset of ADHD, but it also brings up many questions about ADHD that arises after childhood," study author Louise Arseneault said in a news release from Kings College London.

"How similar or different is 'late-onset' ADHD compared with ADHD that begins in childhood? How and why does late-onset ADHD arise? What treatments are most effective for late-onset ADHD? These are the questions we should now be seeking to answer," said Arseneault. She works at the college's Institute of Psychiatry, Psychology & Neuroscience.

Neurodevelopmental disorder

One mental health expert said the study might offer important new insights into ADHD.

"In the medical field, adult ADHD is widely considered a continuation of childhood ADHD that persists into adulthood, or a diagnosis that was missed in childhood but picked up in adulthood," said Dr Matthew Lorber.

Read: ADHD linked to earlier use of illicit drugs in teens

"This study calls both of those assumptions into question," said Lorber, who directs child and adolescent psychology at Lenox Hill Hospital in New York City.

"What is important to consider is that there may be a neurodevelopmental disorder presenting as ADHD in late age that we did not know about," he said. "More studies need to be done looking into this subset, as well as examining if our traditional ADHD treatments will be effective for this older ADHD-like group."

However, another expert was more sceptical of the new study results.

Developmental approach

"I would be surprised if follow-up studies with more rigorous designs confirm these findings," said Matthew Rouse, a psychologist at the Child Mind Institute's ADHD and Behaviour Disorders Centre in New York City.

Read: Are those with ADHD more advanced?

"Mental health disorders have a heavy biological influence, so there are few that don't show up in some way in childhood."

However, study co-author Jessica Agnew-Blais believes that, in some cases, ADHD may not manifest until adulthood.

"It is crucial that we take a developmental approach to understanding ADHD, and that the absence of a childhood diagnosis should not prevent adults with ADHD from receiving clinical attention," she said.

The study appears online in the journal JAMA Psychiatry.

Read more:

Causes of ADHD

Symptoms of ADHD

Diagnosing ADHD


Ask the Expert

ADHD Expert

Dr Renata Schoeman has been in full-time private practice as a general psychiatrist (child, adolescent and adult psychiatry) since 2008, currently based in Oude Westhof (Bellville). Renata also holds appointments as senior lecturer in Leadership (USB) and as a virtual faculty member of USB Executive Development’s Neuroleadership programme. She serves on the advisory boards of various pharmaceutical companies, as a director of the Psychiatric Management Group (PsychMG) and is the co-convenor of the South African Society of Psychiatrist (SASOP) special interest group for adult ADHD, and co-founder of the Goldilocks and The Bear Foundation ( She is passionate about corporate mental health awareness and uses her neuroscience background to assist leaders in equipping them to become balanced, healthy and dynamic leaders that take their own and their team’s emotional, intellectual, social health and physical needs into account. Renata is academically active and enjoys research and collaborative work, has published in many peer-reviewed journals, and has presented at local and international congresses. She is regularly invited to present at conferences and to engage with the media. During her post-graduate studies, she trained at Harvard, Boston in neurocognition and neuroimaging. Her awards include, amongst others, the Young Minds in Psychiatry award from the American Psychiatric Association, the Discovery Foundation Fellowship award, a Thuthuka award from the NRF, and a MRC Fellowship. She also received the Top MBA student award and the Director’s award from USB for 2015. She was a finalist for the Businesswomen’s Association of South Africa’s Businesswoman of the Year Award for 2016, and received the Excellence in Media Work award from SASOP during 2016.

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