Small Area Deprivation and Depression or Anxiety in a Nationwide Cohort

Importance: Prior studies suggest increased risk of mental health conditions in deprived residential areas, but robust evidence leveraging nationwide health care and prescription registers, including primary care, with socioeconomic databases is lacking. Objective: To examine the association between small-area deprivation and depression or anxiety in people aged 10 to 50 years without recent history of these conditions. Design, Setting, and Participants: This nationwide register-based cohort study with sibling analysis was conducted in Sweden January 1, 2015, through December 31, 2023, with analysis completed in January to September 2026. Participants were registered in Sweden throughout the study period, including siblings with discordant-exposure status. Exposure: Small-area deprivation in 2015 was defined for 5984 areas using an Index for Multiple Deprivation in Sweden categorized into quartiles. Main outcomes and measures: Depression or anxiety was defined as the first diagnosis or the first prescription date if no diagnosis was recorded in the study period. Hazard ratios (HRs) for the outcome through December 31, 2023, were computed using Cox regression models adjusted for confounders. Sibling analyses used stratified Cox regression with robust error variance. We separately tested for interactions between small-area deprivation and age, sex, and urbanicity in the association with the outcome. Results: A total of 4 065 375 participants (2 169 625 male [53.4%]; median [IQR] age, 30 [20-41] years), including 1 301 647 siblings, were included. Incidence rates per 1000 person-years for depression or anxiety varied across deprivation levels from 22.8 (95% CI, 22.7-22.9; very low) to 25.6 (95% CI, 25.5-25.7; very high). The HR for depression or anxiety associated with living in the most vs least deprived area was 1.18 (95% CI, 1.17-1.19) and 1.15 (95% CI, 1.13-1.17) in the sibling cohort. Urban (HR, 1.18; 95% CI, 1.17-1.19) and periurban (HR, 1.21; 95% CI, 1.18-1.23) residents in most vs least deprived areas had higher depression or anxiety rates than rural counterparts (HR, 1.11; 95% CI, 1.08-1.14). Conclusions and Relevance: In this study, people in the most vs least deprived areas had increased depression or anxiety rates, and the association remained in sibling comparisons. There were increased rates of depression or anxiety associated with living in the most vs least deprived areas of urban and periurban settings compared with rural settings, potentially reflecting worse outcomes in deprived urban areas or less contact with mental health services in remote and rural areas.