Mental Health and Well-being in Adolescent and Adult Siblings of Persons with Severe Mental Illness: A Scoping review

Systematic knowledge about siblings of persons with mental illness is needed. The aim of this literature review was to gain knowledge about the mental health and well-being of siblings of individuals with severe mental illness (i.e., bipolar disorder, schizophrenia, eating disorders, psychosis) and factors associated with sibling outcomes. We reviewed quantitative studies published between 1990 and 2022 where siblings aged >12 years were compared to healthy control individuals. Eleven studies were included (combined sibling n = 1736). Seven of the 11 studies reported solely more negative outcomes for siblings than for healthy control individuals. Two studies reported both more negative and more positive sibling outcomes, with one study reported solely more positive outcomes and one no difference between siblings and healthy control individuals. The studies reporting negative outcomes had the highest methodological quality. The following factors were associated with sibling outcomes; demographic factors, i.e., age, sex, and number of siblings in the family, contextual factors, i.e., having contact with health care professionals due to own mental health problems, and characteristics of the sibling with severe mental illness, i.e., premorbid adjustment. The findings show that a family system approach with interventions addressing the entire family is indicated when a person is treated for severe mental illness. Further research on sibling outcomes should address methodological challenges such as poor representativeness and a wide age range in samples and use well-validated outcome measures. Factors associated with sibling outcomes should be examined further to increase the understanding of risk and protective factors in siblings.