Ritalin may not be prescribed enough to Atlantic Canadian youth who may need it, a new study from a researcher at Dalhousie University suggests.

The study by Dr. Christiane Poulin, an associate professor of community health and epidemiology, contradicts the widely held belief that Ritalin is being overprescribed to treat attention deficit hyperactivity disorder in children and teenagers.

Her study was made available in March in the online version of the journal Addiction. The research was funded by the Canadian Institute of Health Research and the Canadian Population Health Initiative.

Using data from a 2002 survey of 12,990 adolescents in Atlantic Canada, the study found that six per cent of respondents screened positive for ADHD, but only two per cent of them had been prescribed Ritalin or amphetamines.

"There is a fairly large percentage of teenagers with ADHD who are not known to the health care system," she added.

"Contrary to popular opinion, which is that children and teenagers are largely being prescribed medications for attention deficit disorder, in fact … we found that it’s only about nine per cent of our teenagers who are positive for ADHD are on prescribed Ritalin. That is, in fact, a low rate of utilization."

Poulin's study also found many children who are using Ritalin without a prescription — usually buying it or obtaining it from friends — are at high risk of having ADHD themselves and are, in effect, self-medicating.

Governments and doctors should ask why the health care system has not identified and helped those children and youth, she suggested.

The random sample of students filled out anonymous confidential paper questionnaires for the survey.

New Brunswick Health Minister Michael Murphy said the information in Poulin's study will help youth in his province.

"The more studies there are like this, then the more able we are to treat who needs to be treated," he said.

One of Poulin's previous studies, published in 2001 in the Canadian Medical Association Journal, found that nearly 15 per cent of teenagers gave away at least some of the Ritalin or other stimulant pills that were prescribed to them. About seven per cent of those youth sold their pills.