This antidepressant activity has been studied for therapeutic use, and psilocybin research has been prominent among psychedelics as it has a rapid effect as well as being considered of low toxicity and low addiction tendency. Psilocybin can reduce depressive symptoms for three-six months for people with treatment resistant depression, substance use disorders or with other conditions such as cancer.¹

A small-scale open study of 15 patients has shown a potential use for bipolar depression after a single 25mg dose of synthetic psilocybin along with three psychotherapy sessions over 8 hours on the same day as taking the drug. All patients showed lower depressive symptoms after 3 weeks with 12 considered still to be in remission when symptoms were assessed again at 12 weeks.⁵

Longer-term effects have been shown in a study with 24 patients with major depressive disorder. The participants had two doses of psilocybin with supportive psychotherapy and were assessed at regular intervals over a year for treatment response with a 50% or more reduction in a depressive symptom score and remission. At 12 months, there was still a 75% treatment response and 58% remission rate. In addition, the study reported no serious adverse events related to psilocybin.⁶

Sustained benefits of psilocybin in helping reduce anxiety and depression in patients with cancer have also been reported at six months follow up, after two doses of psilocybin five weeks apart within psychotherapy.¹⁶

In practice, psilocybin was approved for treatment-resistant depression in the same 2023 legislative change in Australia that saw MDMA authorised for use, with similar prescribing authorisation restrictions.²

There is also a move in the USA seeking to reschedule psilocybin from Schedule 1 to Schedule 2 allowing it to be prescribed in certain circumstances under ‘right to try’ legislation. This would allow terminally ill patients to take a drug that has yet to receive FDA authorisation but which has passed through phase 1 trials.^17,18