Researchers say there's been a dramatic rise in the number of people going on medications to treat attention deficit/hyperactivity disorder in Ontario, suggesting factors such as more time spent online and the rise of private assessments for the mental condition could be behind the increase. 

A study published Thursday in JAMA Network Open looked at all prescriptions for stimulant drugs such as Ritalin and Adderall dispensed in the province between 2015 and 2023. 

By 2023, data shows overall annual new stimulant prescriptions were up by 157 per cent compared to 2015. 

The report says prescriptions for ADHD treatment rose throughout the study period and accelerated in 2020, coinciding with the lockdowns of the COVID-19 pandemic. That year prescriptions started increasing 28 per cent per year, compared to only seven per cent from 2015 to 2019. 

Researchers at ICES, North York General, and The Hospital for Sick Children say that sharp increase could be due to several factors: social and environmental changes such as a surge in screen time, increased public awareness and acceptance of ADHD symptoms, and the recognition of people who were previously undiagnosed. 

However, while they acknowledge there is a lack of data on whether the medication was being prescribed appropriately, they also say there may have been some people who were misdiagnosed – when a condition that causes similar symptoms is incorrectly deemed ADHD – or overdiagnosed – when milder symptoms are incorrectly diagnosed as ADHD. 

First author Dr. Daniel Myran said his concern is that some people could be exposed to adverse side effects of the medication unnecessarily, and they might miss an opportunity to treat other mental health conditions. 

The biggest change over the study period was in adult females, with increases of approximately 421 per cent and 369 per cent in ages 25 to 44 and 18 to 24, respectively. 

“Their growth is so quick that in 2023 there are more females age 25 to 44 who've used a stimulant in the past year than males,” Myran, an Ottawa-based family and public health physician and scientist at North York General Hospital, said. 

Historically, the diagnostic criteria for ADHD focused on hyperactivity, which is more common among males. More attention has recently been paid to women’s underdiagnosed inattentive symptoms, such as struggling to stay focused and establish priorities.

“This is part of catching up to that. But the flip side is that it may also be overdiagnosis," Myran said. 

There was also a large increase in the number of children starting to take medications for ADHD, though the jump wasn’t as drastic as the adult groups. 

Girls also outpaced boys with new prescriptions. They were up by 191 per cent in girls aged 10 to 14, and by 67.5 per cent in boys of the same age group. 

During the pandemic a number of private virtual care clinics opened offering ADHD assessments. Myran said these online options both lowered the barrier to diagnosis and potentially led to misdiagnosis or overdiagnosis. He said patients have come into his family practice with inaccurate diagnoses, which actually prompted him to start this study. 

"If you have the wrong diagnosis and you pursue the wrong treatment for it, you may never get the right treatment for what you have," he said.

Medication side effects include loss of appetite, sleep problems and anxiety. There are also long-term implications that can include increased blood pressure and risk of stroke and heart attacks.

"These are things where if you have bad symptoms of ADHD that are preventing you from engaging in education or work, the risk trade-off is clear."

But as these medications become much more broadly used, Myran said, "I think that you start getting into groups of individuals who are being prescribed it where the risk-benefit base ratio may not be as favourable."

Heather Palis, who was not involved in the Ontario study but did conduct one with similar findings out of British Columbia this year, said the rapid rise of new diagnoses also indicates that some of these patients have been underdiagnosed and managing their own symptoms without a health care provider.

Her study published in The Lancet saw the fastest growth in females diagnosed with ADHD, with an estimated rate of growth more than twice that of males during the pandemic.

“That signals to us a population that then needs services and treatment," said Palis, a senior scientist at the BC Centre for Disease Control. That means having access to health care providers who can prescribe, communicate and monitor patients for adverse effects. 

"I think it's really meant to be a first step to now informing how we meet the service needs of people who have these new diagnoses and also work to engage the people that are potentially being left behind,” Palis said. 

This report by The Canadian Press was first published Dec. 11, 2025. 

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