British researchers have described the therapeutic effect of psilocybin in the treatment of depression. Scientists have described two clinical trials with psilocybin, which confirmed its effect on reducing the symptoms of major depressive disorder and on increasing the integration of neural networks of the brain.

Depression is a mental disorder, the prevalence of which is estimated by WHO at 3.8 percent. Studies using neuroimaging have shown changes in the brain associated with depression, for example, in the default brain network, which is associated with introspection, or in the networks of executive control and significance determination, which are responsible for cognitive control. Classical depression therapy uses antidepressants, such as selective serotonin reuptake inhibitors and tricyclic antidepressants, as well as psychotherapy.

In recent years, psilocybin, an agonist of serotonin receptors, has been actively studied and shows its effectiveness in the treatment of depression. He plays a separate role in dealing with resistant depression, which cannot be treated using classical methods. The mechanism of its action is not yet fully understood, but its therapeutic properties are of particular interest for further study and introduction into clinical practice.

Researchers from the UK, led by Richard E. Dawes from Imperial College London, decided to describe the therapeutic effect of taking psilocybin for depression. Scientists conducted an open clinical trial to record the overall effect of psilocybin and a double-blind randomized placebo-controlled trial to compare the use of psilocybin and a standard antidepressant with people with confirmed major depressive disorder.

The first trial included 16 patients with resistant depression. After filling out the Beck depression scale and fMRI at rest, they took one low (10 milligrams) and one high (25 milligrams) dose of psilocybin with a difference of one week. A second assessment of the condition and a scan were performed the day after taking the second dose. Further measurements were carried out remotely one week, three months and six months after taking the second dose of psilocybin.

Indicators of the Beck depression scale range from 0 to 63 points, where 0-13 is considered a variation of the norm, and 29-63 correspond to severe depression. A significant decrease in symptoms on the Beck depression scale in the first trial was recorded a week after the start of the trial (p < 0.001, Cohen's d = 1.78) and persisted after six months (p < 0.001, d = 1.07). fMRI data showed a decrease in modularity (p = 0.012, d = 0.72) and an increase in functional brain connections between the main networks a day after the end of therapy and a correlation of these changes with the Beck depression score six months after the end of therapy (r14 = 0.64, p = 0.023). These results indicate a long-term improvement in the condition after therapy.

In the second trial, the effect of psilocybin was compared with the antidepressant escitalopram. Patients (22 in the psilocybin group and 21 in the escitalopram group) also underwent an initial assessment on the Beck depression scale and fMRI at rest. On the first day, one group took 25 milligrams of psilocybin, and the other (the escitalopram group) 1 milligram of psilocybin, the second dose was given to patients three weeks after the first. In parallel, starting the day after the first dose of psilocybin, patients took placebo capsules or 10 milligrams of escitalopram, depending on the group, for six months and one day (one capsule per day for the first three weeks, then two capsules). Repeated measurements were carried out three weeks after the second psilocybin intake. Psilocybin significantly reduced the severity of symptoms on the Beck depression scale in comparison with the effect of escitalopram (F3,123, 4.47; p = 0.005). In addition, only psilocybin reduced modularity (p = 0.039, d = 0.47) and increased the overall integration of brain neural networks.

Thus, the authors have shown the effectiveness of psilocybin in the treatment of resistant depression, as well as its role in increasing the integration of neural networks of the brain in contrast to the classical antidepressant escitalopram. The authors note that the results of this work will help explain the effectiveness of psilocybin use in psychiatry.

The article was published in the journal Nature Medicine
PHOTO: 3D model of the psilocybin molecule ©

Source: Anastasia Lyashenko,

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