A new study has challenged a US Food and Drug Administration advisory issued in 2004 which concludes that suicidal behaviour may emerge after starting treatment with newer classes of antidepressants such as selective serotonin reuptake inhibitors.

The study, published in the American Journal of Psychiatry, concludes that the risk of suicidal behavior after starting 10 newer antidepressant medications is less than the risk posed by older medications. In addition, the risk of serious suicide attempts or death by suicide generally decreases in the weeks after patients start taking antidepressant medication, according to the researchers, from nonprofit health plan provider Group Health Cooperative.

This study is the first published analysis to compare the risk of suicide attempts before treatment to the risks following treatment. It is based on computerized medical and pharmacy records for more than 65,000 patients who filled prescriptions for antidepressants from 1992 to 2003.

"Our findings show that, fortunately, suicide attempts and death by suicide are rare following the initiation of antidepressants," says Greg Simon, a Group Health psychiatrist and the lead researcher on the study. "The period right after people start taking antidepressant medication is not a period of increased risk. In fact, risk after starting medication is lower than before."

The results show that the number of suicide attempts fell by 60% in adults during the month after antidepressant treatment began, and declined further in the following five months.

Adolescents in the study had more suicide attempts than adults, but as with adults, the rate was highest in the month before treatment and declined by about 60% after treatment began.

Simon said he was concerned the misperception that taking antidepressants could increase suicide risk could lead to fewer people with depression being treated.

The FDA initially called for stronger labelling on antidepressants in March 2004, and later concluded that the drugs also heighten the risk of suicide and suicidal behaviour amongst children and adolescents.