Adding lithium to existing medications does not reduce the risk of suicidality in patients with major depression or bipolar disorder, US researchers say.

Their trial in US veterans who had experienced a recent episode of suicidal behaviour was stopped early ‘for futility’ after results for 519 people (85% depression, 15% bipolar disorder) had been analysed.

At that stage 25.5% of people taking daily lithium (600mg/day titrated upwards) had experienced at least one new event related to suicidality over mean follow-up of 320 days, while the comparable figure for those taking placebo was 23.5% over 313-day follow-up.

The participants, recruited from 29 centres for Veterans’ Affairs across the US (84% men), had a mean age of 43 and the main ethnicity was white (73%).