Karolinska Institutet May 15 2026 A single dose of the psychedelic substance psilocybin can provide rapid relief from depressive symptoms – within just a few days. This is shown by the first randomized, double-blind study in Sweden of psilocybin for depression. The effect persisted for over three months, according to researchers at Karolinska Institutet. Depression is a public health problem that causes great suffering. SSRI drugs are the most common treatment, but many patients do not benefit