Objective: The objective of this study was to characterise the prevalence and/or severity of psychological distress (namely, depression and anxiety symptoms) in siblings of people with mental illness (MI) and to examine correlates of distress in siblings of people with MI.
Method: Studies comparing distress in individuals with and without a sibling with MI were eligible. Studies reporting on correlates of distress in siblings were also eligible. A search of MEDLINE Complete, PsycINFO and Embase was conducted up until 17 March 2022.
Results: Fifteen studies comprising 2304 siblings and 2263 comparison individuals were included. Meta-analyses indicated individuals with a sibling with MI experience significantly greater depressive symptoms (Hedges's g = 0.53, 95% CI = [0.32, 0.73], siblings n = 1962, comparison individuals n = 2248) and anxiety symptoms (Hedges's g = 0.40, 95% CI = [0.19, 0.61], siblings n = 653, comparison individuals n = 533) than those without. The sibling relationship, siblings' locus of control, interpersonal functioning and their appraisal of the impacts of MI were identified as important and potentially modifiable correlates.
Conclusion: Individuals with a sibling with MI experience greater depressive and anxiety symptoms than those without and would likely benefit from support. Future studies are required to elucidate the mechanisms underlying distress in siblings.
Keywords: Psychology; anxiety; depression; mental illness; sibling.