High doses of antidepressants -- selective serotonin reuptake inhibitors such as Prozac or Zoloft -- may raise the risk of suicidal behavior in children and young adults, according to a recent study CBS News reported.

Researchers from the Harvard School of Public Health in Boston found that younger patients who start antidepressant therapy at high doses, rather than the average or typical prescribed doses, were more than twice as likely to try to harm themselves during the first 90 days of treatment.

"Our findings offer clinicians an additional incentive to avoid initiating pharmacotherapy at high-therapeutic doses and to monitor all patients starting antidepressants, especially youth, for several months and regardless of history of [deliberate self-harm]," researchers said.

For the study, researchers analyzed data from 162,625 people - between the ages of 10 and 64 years - with depression who started antidepressant treatment with a selective serotonin reuptake inhibitor at modal (the most prescribed doses on average) or at higher than modal doses from 1998 through 2010.

Researchers said the increase in risk for suicidal behavior corresponds to about one additional event of deliberate self-harm for every 150 patients treated with high-dose therapy. For adults 25 to 64 years old, the difference in risk for suicidal behavior was null.

A previous meta-analysis of antidepressant trials by the FDA suggests that children who received antidepressants had twice the rate of suicidal ideation and behavior than children who were given a placebo.

The findings are likely to inform an ongoing debate in psychiatry -- whether or not it's safe to prescribe antidepressants to children and young adults, CBS News reported.

The study does not address why higher doses might lead to higher suicide risk.

According to CBS News, the experiment was observational, which means that researchers can't say for sure that drug dosage was the only thing that made young patients more likely to hurt themselves.

The findings were recently published in The JAMA Network Journals.