Social inequality in mortality associated with neurodegeneration: a population-based study in Belgium

BACKGROUND: Worldwide, population is ageing, leading to a growing burden of neurodegenerative diseases (NDDs) such as Alzheimer's Disease (AD), Parkinson's Disease (PD). Socioeconomic position (SEP) has shown a persistent negative relationship with mortality over the last decades. The most common indicators of SEP such as income, education, and occupational class have shown to significantly impact life expectancy and other mortality indicators. However, studies on the association between SEP and NDD mortality are rather scarce. Therefore, the aim of this study is to assess whether SEP is associated with NDD mortality, which is crucial in understanding and developing preventive interventions for these diseases. METHODS: A comparative analysis on SEP - in terms of income and education - and deaths associated with dementia and parkinsonism was performed, using log linear Poisson regression. Data consisted of the 2011 Belgian census linked to mortality data for the period 2011-2016. RESULTS: During the 2011-2016 study period, 34,700 Belgian inhabitants aged 65 or older died from an NDD (N = 1,883,182). We observed significantly higher mortality in the lowest educational- and income groups. Education had the strongest association in women, with 1.29 (CI 1.21-1.38) times the MRR in the lowest educated group compared to the highest. In men, income showed the strongest association with 1.11 (CI 1.04-1.18) times the MRR in the lowest income group compared to the highest. The biggest disparities were found in dementia mortality, generally negative association with SEP. For income, we observed a strong negative association on parkinsonism mortality, while we found a reversed pattern with education. CONCLUSIONS: Our study provides evidence supporting the existence of socioeconomic disparities in mortality due to neurodegeneration. We found a strong negative association between SEP and NDD mortality, which varies between men and women and between several NDDs. KEY MESSAGES: • NDDs are rapidly becoming a major public health issue worldwide. • Mortality from these diseases vary between different social groups, differentiated interventions are needed in order to reduce inequalities.