A class of antidepressants thought to raise the risk of suicide among teens may significantly reduce the risk in adults, a review suggests.

In Tuesday's issue of the Canadian Medical Association Journal, researchers from Italy and the World Health Organization reviewed eight studies involving more than 200,000 patients with moderate or severe depression who took selective serotonin reuptake inhibitors (SSRIs).

"Data from observational studies should reassure doctors that prescribing SSRIs to patients with major depression is safe," Dr. Corrado Barbui of the University of Verona and colleagues concluded.

"However, children and adolescents should be followed very closely because of the possibility of increased risk of suicidal thoughts and suicide."

SSRIs include Paxil or paroxetine and Prozac or fluoxetine.

Since 2003, regulators in Canada, the U.S. and Europe have sent out advisories warning that clinical trials suggest SSRIs are linked to an increased risk of suicidal thoughts and behaviour in children and teens.

In 2007, an analysis by the U.S. Food and Drug Administration concluded that SSRIs significantly increased suicide risk for adolescents, offered protection for the elderly and were neutral for adults.

"While the FDA found a neutral effect of SSRIs (or a promoting effect in adults aged 18-25), we found a strong protective effect associated with SSRI treatment in adults," the study's authors wrote.

A commentary accompanying the study called for randomized trials to determine the safety and effectiveness of depression treatments in young adults to help guide doctors.

Dr. John Mann of Columbia University and Dr. Robert Gibbons of the University of Illinois said it was alarming that "concerns about the risk of suicide in youth have led not only to fewer SSRI prescriptions without substitution of alternative medications or psychotherapies, but also to a decrease in predicted rates of diagnosis of mood disorders."