The findings come from a study in which researchers from Imperial College London used psilocybin - the psychoactive compound that occurs naturally in magic mushrooms - to treat a small number of patients with depression in whom conventional treatment had failed.

In a paper, published today in the journal Scientific Reports, the researchers describe patient-reported benefits lasting up to five weeks after treatment, and believe the psychedelic compound may effectively reset the activity of key brain circuits known to play a role in depression.

Comparison of images of patients' brains before and one day after they received the drug treatment revealed changes in brain activity that were associated with marked and lasting reductions in depressive symptoms.

The authors note that while the initial results of the experimental therapy are exciting, they are limited by the small sample size as well as the absence of a control group - such as a placebo group - to directly contrast with the patients.