Childhood socio-economic circumstances and dementia: prospective register-based cohort study of adulthood socio-economic and cardiovascular health mediators

Background This study analysed the association between childhood socio-economic circumstances and the risk of dementia, and investigated the mediating role of potentially modifiable risk factors including adulthood socio-economic position and cardiovascular health. Methods We used a 10% sample of the 1950 Finnish population census linked with subsequent population and health registers (n = 95 381). Information of socio-economic characteristics, family structure and housing conditions at the age of 0-15 years was obtained from the 1950 census. We identified cohort members who developed dementia in 2000-2018 using national hospital, medication and death registers. Discrete time survival analysis using logistic regression and mediation analysis applying the Karlson-Holm-Breen (KHB) method were employed. Results An excess risk of dementia was observed for household crowding [odds ratio (OR) = 1.10; 95% CI 1.02-1.18 for 3 to <4 persons per heated room; OR = 1.19; 95% CI 1.11-1.27 for >= 4 persons], single-father family (OR = 1.27; 95% CI 1.07-1.51) and eastern and northern region of residence (OR = 1.19; 95% CI 1.10-1.28). The effects of single-father family and region of residence were mostly direct with adulthood characteristics mediating 14% and 29% of the total effect, respectively. The largest indirect effect was observed for household crowding mediated through adulthood socio-economic position (47-65%). Conclusions The study shows that childhood socio-economic circumstances are associated with dementia, and that the underlying mechanisms only partly relate to adulthood socio-economic position and cardiovascular health. Socio-economic and health interventions targeted at families with children may carry long-term benefits by contributing to a lower dementia risk in later life.