Patients with psychotic depression who remain on olanzapine after remission more than halve their chance of relapse during the next nine months compared with those who come off the drug, a trial shows.

The study conducted at three hospitals in the US and one in Canada followed 126 adults who had been in remission for eight weeks after an episode of psychotic depression, who were treated with sertraline plus olanzapine.

They were randomised to either continue the combination or have olanzapine replaced with a placebo. All continued on sertraline.

Just 20% of those who continued to take the antipsychotic relapsed during the 36-week trial compared with 55% of those on placebo, the authors reported in JAMA.