*3.1. Search and Selection of Studies*

The detailed steps of the article selection process are depicted as a flow-diagram (Figure 1). Initially, the search yielded 722 articles concerning the hypothetical therapeutic use of psilocybin. This initial search included 8 articles obtained through research in other sources. After, duplicates were removed, 670 articles remained and after the screening of titles and abstracts according to PRISMA statement, 32 of them remained and were further evaluated for inclusion and exclusion criteria. Among them, 26 did not meet the inclusion criteria.

**Figure 1.** Preferred Reported Items for Systematic Reviews and Meta-Analysis (PRISMA) flow-diagram of database search, study selection and articles included in this systematic review with meta-analysis. \* The works from Griffiths et al., 2016 [6], Ross et al., 2016 [19] and Grob et al., 2011 [20] were divided into several effect sizes based on different times of follow-up after psilocybin administration. (The division of each work in several effect sizes is indicated by the letters in unpaired parenthesis in Table 1).

Then, seven articles were assessed for eligibility through full-text evaluation and four of them were excluded (Stroud et al., 2018 [21], Lyons and Carhart-Harris, 2018 [22], Carhart-Harris et al., 2017 [23] and Carhart-Harris et al., 2016 [24]), because they were secondary analyses of the same data, and as such none was eligible since a true control group was not present in either of them. Finally, three articles were included in qualitative synthesis and three of them were divided into several effect sizes based on different times of follow-up after psilocybin administration. In a general view, the three articles studied the effects of psilocybin in the treatment of depression and anxiety associated with a life-threatening disease. The data from Ross et al., 2016 [19] was divided in seven data groups and the data from Griffiths et al., 2016 [6] and from Grob et al., 2011 [20] were divided into two data groups each, considering different times of follow-up after psilocybin administration. In total, 11 effect sizes were included in this meta-analysis.


**Table1.**Characteristicsoftheincludedstudiesinthissystematicreviewwithmeta-analysis.

1 The letters in unpaired parenthesis indicate the division of each study in several effect sizes.
