New generation antidepressants achieve almost no benefit compared with placebo in mild to moderate depression, with slightly more benefit in severe depression but only because of less response to placebo, a meta-analysis of clinical trial data has shown.

Researchers analysed all available data from clinical trials submitted to the US Food and Drug Administration for the licensing of four selective serotonin or serotonin-noradrenaline reuptake inhibitors—fluoxetine (Prozac), venlafaxine (Efexor), nefazodone (Serzone), and paroxetine (Seroxat, Paxil).

They analysed the degree to which people improved in relation to the initial severity of the depression in people randomised to drug or placebo.

Results showed almost no difference between the effects of drug treatment and placebo at moderate levels of initial depression, rising to a relatively …