25 April 2023

CIRANO study on overdiagnosis of ADHD in Quebec

On April 25, 2023, a round table was held at CIRANO bringing together specialists in the fields of economics, sociology and psycho-education to discuss the results of a CIRANO study that unequivocally documents the phenomenon of overdiagnosis of ADHD and sounds the alarm on this extremely worrying issue. In the report, Surdiagnostic du TDAH au Québec : Impact de l’âge d’entrée à l’école, différences régionales et coûts sociaux et économiques, Catherine Haeck and Philip Merrigan, both professors at ESG UQAM and CIRANO Fellows, and their co-authors demonstrate the magnitude of the phenomenon of overdiagnosis and overtreatment of ADHD in Quebec elementary school students based on unpublished data from the Régie de l'assurance maladie du Québec on the medical records of 800,000 youth. 

During the roundtable, Catherine HaeckPhilip Merrigan and Pierre Lefebvre, associate professor at ESG UQAM, presented the results of their CIRANO study. Marie-Christine Brault, professor at UQAC and holder of the Canada Research Chair in Children, Medicine and Society, and Isabelle Boisvert, scientific coordinator at the Institut national d'excellence en santé et en services sociaux, presented other research results, findings and recommendations on ADHD. 

The event was rich in discussions between the panelists and many participants.

Study highlights: Younger classmates have 35% higher rates of ADHD diagnosis and medication than older classmates

  • The majority of children are first diagnosed at a very young age, between 6 and 8 years old, so it's all about elementary school
  • Diagnosis rates are twice as high in the region as in Montreal
  • Children from families on social assistance have significantly higher rates of diagnosis
  • Confusing immature behaviour in the classroom with ADHD and misdiagnosing students with ADHD may have cost the state more than $50 million in medical services and drugs covered by the drug plan

Read the full report

Read the article in PERSPECTIVES