Ritalin use is almost twice as high among children whose parents divorce compared with those who continue to live with two biological parents, a Canadian study suggests.

Ritalin, or methylphenidate, is commonly prescribed for attention deficit hyperactivity disorder, or ADHD, in children.

Use of the drug has increased rapidly over the past few decades in Canada, the U.S., the Netherlands, Israel and Australia, raising questions about whether it is overprescribed or prescribed inappropriately in children.

The study in Tuesday's issue of the Canadian Medical Association Journal attempted to tease apart whether family structure makes a difference in the higher prescription rate, but the findings do not explain why the prescription rates are higher, said the study's author, Lisa Strohschein.

"I've got the what, but not the why," said Strohschein, a sociologist at the University of Alberta in Edmonton.

Stress of divorce?

Previous studies suggest children who live with a single parent or a parent and step-parent were more likely to be prescribed Ritalin.

But a child could be living in a single-parent household because of several reasons — divorce, loss of parent to death or because they were born to a single parent. The earlier research was not clear about whether divorce itself makes a difference in Ritalin prescription rates.

When Strohschein looked at prescription rates between 1994 and 2000 among 4,151 children whose parents hadn't divorced and 633 children whose parents had, she found Ritalin use was significantly higher among children whose parents divorced.

In two-parent families, 3.3 per cent of children were prescribed the drug, which rose to 6.1 per cent among the children whose parents had divorced.

"It is possible that the stress of divorce subsequently elevated child behavioural problems to a point that necessitated methylphenidate use," Strohschein concluded. "However, one cannot rule out alternative explanations."

For example, since ADHD is thought to have a genetic component, there may be a greater likelihood of passing on the disorder among parents with a history of mental health problems who divorce, Strohschein proposed.

Or, the anxiety, sadness and other emotions that children feel after divorce may lead to more contact with the health-care system. Visits to the doctor after a divorce occur as parents and doctors are on the lookout for problematic behaviour, and a child's symptoms may be mislabelled as ADHD.

The Statistics Canada survey results on which the study was based did not include questions to test whether Ritalin is prescribed inappropriately to children of divorce.

Be cautious in prescribing

Nonetheless, the findings should serve as a reminder to doctors to be cautious in prescribing drugs for ADHD to children after a divorce, said Dr. Abel Ickowicz, the psychiatrist-in-chief at the Hospital for Sick Children in Toronto.

"Because … if we are going too quick to prescribe medication, like Ritalin, like methylphenidate, we may not only be masking the normal process of adaptation to divorce, but we may be contributing to the degree of distress the children of divorce are experiencing."

All of the explanations Strohschein proposed likely have some validity, said Dr. Anton Miller, a developmental pediatrician and child health researcher at the University of British Columbia's Centre for Community Child Health Research.

Miller added his own suggestion, saying the stress of dealing with ADHD behaviour in a child may contribute to divorce.

With files from the Canadian Press