Tree Imagery in Drawing Tests for Screening Mental Disorders: A Systematic Review and Meta-analysis

Abstract

Background Tree imagery in drawing tests has demonstrated effectiveness in predicting mental disorders; however, there remains a lack of uniformity in the selection and interpretation of predictors. This study aimed to integrate various tree imagery characteristics in mental disorders through a systematic review and meta-analysis and to further identify valid indicators for predicting mental disorders. Methods A search of the following electronic databases was performed in May 2023: PubMed, Web of Science, Embase, EBSCO, CNKI, VIP, and Wanfang. Screening and checking of the literature were performed independently by two authors. A total of 42 studies were included in the meta-analysis. The strength of the association between drawing characteristics and mental disorders was measured by the ratio (OR) with a 95% CI. Publication bias was assessed using a funnel plot, Rosenthal’s fail-safe number (Nfs), and the trim and fill method. Results The analysis demonstrated a total of 45 drawing characteristics that appeared at least three times in previous studies, 24 of which were found to significantly predict mental disorders. The effective predictors could be categorized into five categories: blackened out, scribbled lines, oddly shaped, no vitality, and overly simple. Subgroup analyses indicated that “blackened tree”, “no motion”, and “excessive separation” were specific indicators of affective disorders, whereas “roots” was an indicator of thought disorders. Common indicators for mental disorders included “weak or intermittent tree lines”, “no additional decoration”, “simplified drawing”, “small drawing size” and “very small tree”. Conclusion This study confirms the value of drawing tests in screening for mental disorders, and provides reference for the selection and interpretation of drawing indicators.