US Food and Drug Administration researchers have found that people under 25 taking antidepressants are more than twice as likely to experience suicidal thoughts and behaviour than those on placebo.

The analysis of 372 clinical trials of almost 100,000 people observed there was an age dependent risk of suicide linked to taking antidepressants – those under 25 had an increased risk of suicidal behaviour, those between the ages of 25 and 64 were possibly “protected” from suicidal ideation, while those over 65 had a reduced risk of suicidality.

Of the 99,231 patients reviewed, eight committed suicide, 134 attempted suicide, 10 made preparations but did not attempt suicide, and 378 thought about committing suicide but did not go any further.

The findings, published in the British Medical Journal, reinforce the view that adolescents and young people have an increased risk of suicide when taking these medications.

In May 2007, the FDA proposed that antidepressant manufacturers should update existing black box warnings to include warnings of increased risks of suicidal thoughts and behaviour in people aged 18-24 during the first one-two months of treatment. This followed similar labelling changes made in 2005.

The FDA has announced more research is required, particularly focussing on specific age groups.