New prescriptions for stimulants—mostly attention-deficit hyperactivity disorder [ADHD] drugs—doubled since the COVID-19 pandemic began among adults in Ontario, according to a study published today in CMAJ.

A team led by researchers from the Institute for Clinical Evaluative Services (ICES) in Toronto parsed data from the Narcotics Monitoring System and population-level health administrative data to estimate monthly rates of new stimulant dispensing to adults in Ontario from January 2016 to June 2024.

“Prescribed stimulants (e.g., amphetamine salts, methylphenidate) are central nervous system agents indicated for the treatment of attention-deficit/hyperactivity disorder (ADHD) and, in certain jurisdictions, for narcolepsy and other off-label uses, including adjunctive treatment of major depressive disorder,” the study authors wrote.

“Historically, these medications have primarily been prescribed in pediatric populations; however, over the past 2 decades, ADHD diagnoses and stimulant prescriptions among adults have risen steadily worldwide,” due to increased recognition of adult ADHD, diagnoses made in adulthood, and changes in diagnostic methods. “However, questions persist concerning the drivers and potential consequences of increased prescription stimulant use among adults.”

Recent data suggest increased stimulant prescribing outside of Canada, which the researchers said raises questions about potential ADHD misdiagnoses, access disparities for both diagnosis and treatment, and the long-term effects of inappropriate stimulant use. 

Increased prescribing for young adults

Of 327,053 adults who started taking stimulants, the median age was 31 years, and 55.4% were women. New stimulant prescribing was stable before the COVID-19 pandemic (change in monthly rate per 1,000 people, 0.0004), fell immediately after pandemic onset (−0.067), and then accelerated (0.0029), rising 7.3-fold from 0.16 to 0.44 new monthly dispensations per 1,000 people from January 2016 to June 2024. 

Relative to before the pandemic, new recipients during the pandemic were more likely to be aged 25 to 34 years (26.5% vs 32.8%) and women (48.0% vs 59.0%), and the drugs were less likely to be started by psychiatrists (25.5% vs 18.0%) and more likely to be written by nurses or nurse practitioners (1.7% vs 9.6%). 

Over the past 2 decades, ADHD diagnoses and stimulant prescriptions among adults have risen steadily worldwide.

By June 2024, the monthly rate of new stimulant prescribing rate reached 1.13 per 1,000 people aged 18 to 24 years, 0.77 per 1,000 among those aged 25 to 34 years, and 0.63 per 1,000 in those aged 35 to 44 years.

After the pandemic began, most adults received a long-acting stimulant only (91.6%), usually lisdexamfetamine (48.1%) or long-acting methylphenidate (41.0%). Higher initial doses were also prescribed (28.4% vs 19.9%).

The expected indication for the stimulant was ADHD or childhood behavioral diagnoses for 26.4% of new recipients, anxiety or depression for 28.5%, drug dependence for 2.3%, and a sleep disorder for 1.2%. Just under one third (28.7%) of adults had a previous health care visit for ADHD, with the first visit occurring a median of 2.2 years before prescription.

Early in the pandemic, there was a rapid increase in the proportion of new stimulant prescribing for ADHD or childhood behavioral diagnoses, from 23.8% in February 2020 to 31.3% in June 2024, due to a threefold increase in the absolute number of new stimulant recipients with these diagnoses. 

At the same time, the percentage of new stimulant prescriptions for other diagnoses fell during the pandemic, although the absolute numbers rose for all indications. For example, the proportion of new stimulant recipients with an anxiety or depression diagnosis dropped from 30.8% in February 2020 to 23.2% in June 2024, while the absolute number of new recipients with these diagnoses grew 74%.

‘Questions about how diagnoses are being made’ 

During the pandemic, the proportion of people starting stimulants who had any previous mental illness or substance use disorder diagnosis dropped from 26.8% to 22.1%. The prevalence of ADHD as the indication for stimulant prescribing climbed after pandemic onset (from 20.9% to 29.1%), and the median time between the first visit for an ADHD diagnosis and stimulant initiation plunged from a median 2,493 days before the pandemic to 348 days during the pandemic.