People with major depressive disorder can see a rapid and lasting improvement after a single dose of the psychedelic drug dimethyltryptamine (DMT) when it is combined with psychotherapy, doctors have said.

A small clinical trial involving 34 people found that psychedelic-assisted therapy prompted a swift reduction in depressive symptoms that endured long after the drug had worn off, with some still feeling the benefits six months later.

“There is an immediate antidepressant effect that is significantly sustained over a three-month period and that’s exciting because this is one session with a drug, embedded in psychological support,” said Dr David Erritzoe, a psychiatrist at Imperial College London and lead investigator on the trial.