Data extraction and outcome measures

Data extraction and calculations were done independently by two reviewers (J.K.) (I.M.M.). In case of disagreement between the two researchers, a third reviewer (A. C.) was consulted. According to CAMARADES guidelines and predefined protocol, extracted data included study design and sample characteristics, details of interventions and regimens and outcomes data. If an additional drug or procedure other than chronic stress exposure was applied in the study, only data from the control groups (without additional interventions) were extracted. One specific effect size from the single behavioral test common for included studies was used in the meta-analysis. Multiple subgroups within a single study (e.g., sex of animals or different rodent strains) were included as independent standardized mean difference (SMD), provided that each treatment group had a separate matched control group. If the number of animals in the group was reported as a range (e.g., 8–10; 9–10), the middle or the lowest number of animals per group was used for the meta-analysis. When results were available only in graphical format, data were extracted using WebPlotDigitizer graph digitization software [46] recommended for use in systematic reviews [47]. Missing data were requested from the corresponding authors of the primary studies.