One of the most notable effects (or perhaps even causes) of depression is the tendency to view future life events in a highly unrealistic and grim way, where the severity of the illness co-varies with the severity of pessimistic forecasting.
To find out whether psilocybin – the main psychoactive compound found in “magic” mushrooms – could be useful in nudging depressed individuals away from exaggerated negativity, the Psychedelic Research Group at Imperial College London (ICL) recruited 15 volunteers and gave them psilocybin.
Each of the participants, who all had treatment-resistant depression, were given the drug in two oral dosing sessions (10 and 25 mg) with a week in-between, and were provided with psychological counselling before, during, and after each of the sessions.
Prior to receiving the drug, the participants (including the 15 matched, untreated non-depressed controls) were asked to complete the Prediction of Future Life Events (POFLE) task, which required them to predict the likelihood of certain life events occurring within a 30-day period, followed by an assessment of the accuracy thereof.
Going through the measurements collected at baseline and one week after the second dosing session, the researchers found that one week after psilocybin treatment the depressed participants showed significant reductions in their pessimism bias, as well as improved mood, with the change in both variables being significantly correlated.
Such outcomes were not, however, observed in the control group. “Taken together, these findings indicate that the psychologically supportive administration of psilocybin remediates negative cognitive biases characteristic of severe depression – enabling individuals to forecast their futures more correctly <…>,” explained the authors.
Study limitations, some of which have been admitted by the authors themselves, include small sample size, almost exclusively male Caucasian composition of the subject group, the possibility of natural decline in depressive symptoms over time, and the possibility of psychological assistance providing more benefit than the drugs themselves.
The research duo Taylor Lyons and Robin Lester Carhart-Harris from ICL are now calling for “further controlled studies <…> to better determine the causality, reliability, specificity and durability of these findings”.
Full text of study is available on the website of the journal Frontiers in Psychology.