Hamilton, Ontario—Prescription painkillers are more likely to be the jumping off point for opioid addiction than heroin, according to a new Canadian study. The article, published online recently by the journal Biology of Sex Differences, involved 503 patients attending 13 methadone clinics in Ontario. McMaster University researchers report that more than half, 52%, of women and more than a third, 38%, men reported physician-prescribed painkillers as being their first contact with opioid drugs. The study sought to identify any significant gender differences between male and female patients, finding that, compared to men, women had more physical and psychological health problems, more childcare responsibilities, and were more likely to have a family history of psychiatric illness. Men were more likely than women to be in employment, and were more likely to smoke cigarettes.