Baseline income, follow-up income, income mobility and their roles in mental disorders: a longitudinal intra-generational community-based study

BACKGROUND: Although a number of studies have found that income mobility associated with an elevated risk of mental disorders, existing research does not provide sufficient evidence of how exactly individuals’ experience of income mobility per se affects their risk of mental health outcomes. This present study aimed to explore roles of baseline income, follow-up income, and income mobility in the development of mental disorders using an intra-generational, longitudinal follow-up study. METHODS: We used data from the Montreal South-West Longitudinal Catchment Area Study. A total of 1117 participants with complete information both on income and past 12-month diagnoses of mental disorders were selected for this study. Diagonal Reference Models were used to simultaneously examine roles of income at baseline, income at follow-up, and income mobility in mental disorders during a 4-year follow-up. RESULTS: Both baseline and follow-up income were important predictors for any mental disorder and major depression among males and females. Those with low income had a higher risk of any mental disorders and major depression. No evidence was found to support an association between income mobility (neither downwards nor upwards) and mental disorders. Marital status was uniquely associated with any mental disorder among males. Having a pre-existing diagnosis of any mental disorder at origin was associated with any mental disorder and major depression at the end of the 4-year follow-up. CONCLUSIONS: This study first simultaneously examined roles of income at baseline, at follow-up, and mobility in mental disorders among a large-scale intra-generational community-based study. This present study provides additional evidence on how income is associated with an individuals’ likelihood of mental disorders.