The Effects of Income Change on Mental Health: An 18-Year Longitudinal Population Study
Pekka Martikainen, Centre for Health Equity Studies
Heta Moustgaard, University of Helsinki
Liina Junna, University of Helsinki
Lasse Tarkiainen, University of Helsinki
We assess the association between psychotropic drug use and individual income longitudinally, controlling for both unobserved individual differences, and observed time-variant time trend, age, marital status and employment status. The register-based data comprises an 11% nationally representative random sample of Finnish residents aged 30 to 63 years, followed annually from 1996 to 2013: the final sample includes 389,428 individuals and 4,722,359 person-years. We estimate ordinary-least-squares and fixed-effects models, the latter controlling for all unobserved time-invariant individual characteristics. Adjusted for observed sociodemographic confounders, the doubling of income decreased the likelihood of psychotropic drug use by 0.63 percentage points in the ordinary-least-squares model (β= -0.0091, 95% confidence interval: -0.0102, -0.0080; P < 0.001), and by 0.10 percentage points in the fixed-effects model (β= -0.0014, 95% confidence interval: -0.0022, -0.0006; P < 0.001). These associations were slightly weaker for women and individuals with a high baseline income. The contemporaneous association observed between income and psychotropic drug use was enduring - albeit very small - even when time-invariant individual differences and sociodemographic changes were accounted for.
Presented in Session 1172: Health, Wellbeing, and Morbidity