Prevalence of parental mental illness and association with socioeconomic adversity among children in Sweden between 2006 and 2016: a population-based cohort study

BACKGROUND: Children of parents with mental illness are a vulnerable group, but their numbers and their exposure to adversity have rarely been examined. We examined the prevalence of children with parents with mental illness in Sweden, trends in prevalence from 2006 to 2016, and these children's exposure to socioeconomic adversity. METHODS: We did a population-based cohort study among all children (aged <18 years) born in Sweden between Jan 1, 1991, and Dec 31, 2011, and their parents, followed up between Jan 1, 2006, and Dec 31, 2016. We included children who were identified in the Total Population Register and linked to their birth parents, excluding adopted children and those with missing information on both birth parents. We used a comprehensive register linkage, Psychiatry Sweden, to follow up for indicators of parental mental illness and socioeconomic adversity. Marginal predictions from a standard logistic regression model were used to estimate age-specific, 3-year period prevalence of parental mental illness and trends in prevalence for 2006-16. Using cross-sectional data on each child, indicators of socioeconomic adversity were compared between children with and without concurrent parental mental illness using logistic regression. FINDINGS: Of 2 198 289 children born in Sweden between Jan 1, 1991, and Dec 31, 2011, we analysed 2 110 988 children (96·03% of the total population). The overall prevalence of children with diagnosed parental mental illness between 2006 and 2016 was 9·53% (95% CI 9·50-9·57). This prevalence increased with age of the child, from 6·72% (6·65-6·78) of the youngest children (0 to <3 years) to 10·80% (10·73-10·89) in the oldest (15 to <18 years). The prevalence of diagnosed parental mental illness increased from 8·62% (8·54-8·69) in 2006-09 up to 10·95% (10·86-11·03) in 2013-16. Children with any type of parental mental illness had markedly higher risk of socioeconomic adversity, such as living in poorer households or living separately from their parents. INTERPRETATION: Currently, 11% of all Swedish children have a parent with a mental illness treated within secondary care. These children have markedly higher risk of broad socioeconomic adversity than do other children. There is a need to understand how socioeconomic adversity and parental mental illness influence vulnerability to poor life outcomes in these children. FUNDING: European Research Council, National Institute for Health Research, Region Stockholm, and the Swedish Research Council.