*3.4. Primary Outcomes: E*ff*ects of Psilocybin on Depression and Anxiety*

BDI and STAI were considered the psychometric scales for this work since they are the most widely used in clinical settings to quantify symptoms of either depression or anxiety.

The meta-analysis results for the effects of psilocybin in depression through BDI are graphically reported in Figure 3A and Table 2. For BDI, 11 effect sizes were considered, including 92 patients, with a diagnosis of depression and anxiety associated with a life-threatening disease. It was concluded that the intervention group was significantly favored when compared to the control group (WMD = −4.589; 95% CI = −4.207 to −0.971; *p*-value = 0.002). For these results, a fixed effects model was used, given the homogeneity of the studies (I<sup>2</sup> = 0%).

**Figure 3.** Forest plots of comparisons of the effects of psilocybin on the primary outcomes of this meta-analysis ((**A**) Beck Depression Inventory (BDI); (**B**) State-Trait Anxiety Inventory (STAI)-Trait; (**C**) STAI-State).


**Table 2.** Effects of psilocybin on depression and anxiety.

WMD—weighted mean differences; CI—confidence interval; \* Indicates a significant result.

The meta-analysis results for the effects of psilocybin in anxiety through STAI-Trait and STAI-State are graphically reported in Figure 3B,C, respectively and Table 2.

For STAI-Trait, 11 effect sizes were considered, including 92 patients, with a diagnosis of depression and anxiety associated with a life-threatening disease. Among these, 28 patients had genitourinary cancer, 26 had breast cancer, 16 had digestive cancer, 12 had hematologic malignancies and 10 had other oncologic pathologies. All patients were in advanced stages of their illnesses and some had recurrent metastatic diseases. Apart from that, all patients had also been diagnosed using the DSM V meeting criteria for either chronic adjustment disorder with anxiety, chronic adjustment disorder with mixed anxiety and depressed mood, dysthymic disorder, GAD, MDD or dual diagnosis between GAD and MDD or GAD and dysthymic disorder.

It was concluded that the intervention group was significantly favored when compared to the control group (WMD = −5.906; 95% CI = −7.852 to −3.960; *p*-value < 0.001). For these results, a fixed effects model was used, given the homogeneity between studies (I<sup>2</sup> = 0%).

For STAI-State, 9 effect sizes were considered, including 41 patients, with a diagnosis of depression and anxiety associated with a life-threatening disease (oncologic conditions). For this outcome, it was concluded that the intervention group was significantly favored when compared to the control group (WMD = −6.032; 95% CI = −8.900 to −3.164; *p*-value < 0.001). For these results, a fixed effects model was used, given the homogeneity between studies (I<sup>2</sup> = 0%).
