Medications are definitely needed in some cases, he says, "but definitely not in the quantity that we are seeing them."
Diagnosing ADHD has been a medical minefield ever since the rise of the so-called Ritalin Generation in the 1980 and 90s. With no blood test or any other biological means to confirm an ADHD case, psychiatrists, psychologists or a general practitioner diagnose children after a clinical assessment or, often, with behavioural reports from parents and teachers.
But evaluations are subjective and the distinction between ADHD symptoms and standard childhood traits can be quite subtle - such as forgetfulness, and fidgeting.
"We don't have a biological test to rule out ADHD and that gives rise to the possibility that ADHD may be misdiagnosed, or missed," says Rosemary Tannock, a psychologist at Toronto's Hospital for Sick Children who studies children with the disorder.
Dr. Tannock says biological signs of the syndrome exist. Imaging studies show brain development in children with ADHD lags two to three years behind a normal brain, particularly in the prefrontal cortex, an area involved with self control. The less mature a brain looks, she says, the more severe the symptoms, though kids with ADHD score average and above average in IQ tests.
Yet because males with ADHD tend to be boisterous and disruptive and females with the disorder tend to be distracted and daydream, boys are more likely to be identified and girls are more likely to be missed, she says.
"Everything we knew about ADHD was based on behaviour of 11 year old boys," said Dr. Tannock, who also works with the Ontario Institute of Studies in Education, training teachers to teach children with the disorder.
"The imbalance of medications comes because girls are not seen as having serious behavioural problems - they're not hyperactive."
A growing awareness that girls also suffer ADHD has added to the increase in drug use, experts say and IMS data show prescriptions for females rising by more than 60 per cent since 2005. But prescriptions for males still account for the vast majority.
Prof. Bradley, who taught elementary school before joining McGill to teach prospective teachers some 40 years ago, believes that schools have removed "the time to be male." Shorter recesses, and lunch and gym periods, and the decline of metal and woodworking classes all contribute, he says, to boys' restlessness in the classroom and the likelihood of being picked out for acting up.
In his home province, the story is particularly striking. Quebec, where boys drop out of school at a rate of nearly 40 per cent - the highest in Canada, and one of the highest in the western world - also leads the country in ADHD drug use.
IMS data show ADHD drug use rising in all provinces, but Quebec's rate of more than 10 doses a day for every 1,000 people in the population, tops the list. Nova Scotia follows with 9.2 daily doses, while consumption in B.C., the lowest user in the country, is half that amount.
Prescription rates for ADHD drugs, which like cocaine, are psycho-stimulants, can also vary by school board, says Wendy Roberts, a developmental pediatrician at Sick Kids and Toronto's Bloorview MacMillan Children's Centre.
In certain boards, Dr. Roberts says, teachers are more likely to say to parents - "I'm having a problem with [your]child, and so you should go and see Dr. So-and-So," confident the doctor will recommend drugs, says Dr. Roberts. "Some parents have certainly told me that they have felt they could not take their child back to school unless he was taking a medication …I think we're jumping to medication too quickly.
"There's no question if you have a child that's going to sit quietly in your classroom, you're going to be a happy teacher."