VMany people with severe depression are not helped by conventional drugs and therapies. They are considered “resistant to therapy”. For a long time there was little hope for her, because one waits in vain for innovative approaches to medicines for the treatment of depression. So-called psychedelics, i.e. hallucinogenic substances that can cause intoxication and are therefore consumed for pleasure, are currently experiencing a renaissance in depression research. This includes lysergic acid diethylamide, LSD for short, but also the alkaloid psilocybin, which occurs naturally in so-called “magic mushrooms”.
Various studies have shown that psilocybin has an antidepressant effect. How exactly the substance works in the brain, however, was previously unclear. In “Nature Medicine”, researchers led by neuroscientist Robin Carhart-Harris from Imperial College London now present evidence that psilocybin increases the “functional connectivity” between different areas in the brain. To put it simply, certain nerve cells communicate more with each other after taking psilocybin than before. Depressives tend to suffer from and get stuck in rigid negative thinking about themselves and the future. Psychologists suspect that hallucinogens may disrupt these patterns.
For the current study, a total of 59 patients with major depression were treated in two different trials. On the one hand, 16 patients received two doses of psilocybin one week apart, after which an image of their brain was taken with a so-called functional MRI scan. This also made it possible to map the blood flow and thus the activity of certain regions in the brain. This showed the increased connectivity between the brain areas. “The increased functional connection could correspond to a described subjective increased flexibility and emotional relaxation,” says Matthias Liechti, Professor of Clinical Pharmacology at the University Hospital Basel. He was not involved in the current study, but he has been researching the effects of psychedelics for a long time. In healthy people, the effect of psilocybin on brain function has already been examined in MRI, i.e. magnetic resonance imaging, he reports.
The second study was a 43-patient, double-blind, randomized study comparing the effects of psilocybin to escitalopram. One group of patients received two effective doses of psilocybin three weeks apart and a placebo drug for several weeks. In the control group, subjects received psilocybin at a dose low enough to be considered a placebo and took the antidepressant escitalopram for six weeks. In fact, the subjects who received psilocybin were less depressed than those who took the common drug. This effect continued three weeks later. The same functional changes were also seen in the brain of these subjects, meaning that connectivity was increased.
The current research work is causing a stir, especially since it is being published in a prominent specialist journal. “However, this publication does not describe any new study or new clinical data,” says Liechti. Only the description of the imaging data and its connection with the therapeutic effect is new. “Unfortunately, there is no analysis of the correlation between acute effects and sustained effects of psilocybin, nor an analysis of the correlation between acute subjective effects and imaging.” So it will probably be some time before psilocybin can be tested in extensive clinical studies.