Background Childhood family income variation is an understudied aspect of households' economic context that may have distinct consequences for children. We identified trajectories of childhood family income over a 12-year period, and examined associations between these trajectories and later psychiatric disorders, among individuals born in Sweden between 1987 and 1991 (n=534 294).
Methods We used annual income data between the ages of 3–14 years and identified 5 trajectories (2 high-income upward, 1 downward and 2 low-income upward trajectories). Psychiatric disorders in the follow-up period after age 15 were defined from International Classification of Disease (ICD)-codes in a nationwide patient register. Multiadjusted risks for all psychiatric disorders, as well as for specific psychiatric diagnoses, were calculated as HRs with 95% CIs.
Results Of the 5 identified income trajectories, the constant low and the downward trajectories were particularly associated with later psychiatric disorder. Children with these trajectories had increased risks for psychiatric disorder, including mood, anxiety, psychotic disorders and attention deficit/hyperactivity disorder. The association remained, even after adjusting for important variables including parental psychiatric disorder. In contrast, the relationship was reversed for eating disorders, for which children in higher income trajectories had elevated risks.
Conclusions Findings show that children growing up in a household characterised by low or decreasing family income have an increased risk for psychiatric disorder. Continued work is needed to reduce socioeconomic inequalities in psychiatric disorders. Policies and interventions for psychiatric disorders should consider the socioeconomic background of the family as an important risk or protective factor.
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Contributors EB, SC and ARP originated the idea. EB and SC analysed the data. EB wrote the manuscript draft. All authors contributed to the interpretation of the results and to the writing of the final article.
Funding This study was supported by a grant from the Swedish Society for Medical Research (CB), Swedish Council for Working Life and Social Research (grant number 2013-2729, EB).
Competing interests None declared.
Ethics approval This project has been reviewed and approved by the Regional Ethical Review Board of Karolinska Institutet, Stockholm, Sweden (dnrs: 2010/1185-31/1 and 2013/1118-32).
Provenance and peer review Not commissioned; externally peer reviewed.
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