In the second one, the participants were depressed but not as severely, and they were not told whether they had been given psilocybin or a placebo that turned out to be an antidepressant. In addition to the drugs, all the participants received the same type of psychotherapy.
The scans, which were done before and after treatment, showed the psilocybin treatment reduced connections within brain areas that are tightly connected in depression including the default mode, salience, and executive networks, and increased connections to other regions of the brain that had not been well integrated.
These changes lasted until the study ended three weeks after the second psilocybin dose. No such changes were seen in the brains of those who received escitalopram, suggesting that psilocybin acts differently on the brain than SSRIs.
Psilocybin and other serotonergic psychedelics like ayahuasca affect 5-HT2A receptors, which are plentiful in brain networks that become overactive in depression. One hypothesis is that the drugs briefly disrupt these connections, giving them a chance to reform in new ways in the ensuing days and weeks.
“In previous studies we had seen a similar effect in the brain when people were scanned whilst on a psychedelic, but here we’re seeing it weeks after treatment for depression, which suggests a carry-over of the acute drug action,” said Robin Carhart-Harris, Ph.D., who directs the Neuroscape Psychedelics Division at UCSF and is the senior author of the study.
Researchers also caution that while these findings are encouraging, patients with depression should not attempt to self-medicate with psilocybin.
The trials took place under controlled, clinical conditions, using a regulated dose formulated in a laboratory, and involved extensive psychological support before, during, and after dosing.
But the study points to a mechanism that, if it holds up, may explain both how psilocybin helps to alleviate depression and potentially other debilitating psychiatric conditions.
Source: Medindia
