The role of literacy, occupation and income in dementia prevention: the São Paulo Ageing & Health Study (SPAH).

BACKGROUND: Dementia is now a major public health issue in low- and middle-income countries, and strategies for primary prevention are needed. This study aimed to estimate the proportion of cases of dementia attributable to illiteracy, non-skilled occupation and low income, which are common, potentially modifiable social adversities that occur along the lifespan in low- and middle-income countries.
METHODS: This report is based on data from the São Paulo Ageing & Health Study (SPAH) study (N = 2003). All individuals aged 65 years and older residing within pre-defined socially deprived areas of the city of São Paulo, Brazil, were included. The outcome of interest was prevalent dementia. Indicators of socioeconomic position (SEP) were literacy (distal indicator), highest occupational attainment (intermediate indicator), and monthly personal income (proximal indicator). We estimated the proportion of prevalent dementia attributable to each SEP indicator (illiteracy, non-skilled occupations and low income) by calculating their population attributable fractions (PAF).
RESULTS: Dementia was more prevalent amongst participants who were illiterate, had non-skilled occupations and lower income. Illiteracy, poor occupational achievement and low income accounted for 22.0%, 38.5% and 38.5% of the cases of dementia, respectively. There was a cumulative effect of socioeconomic adversities during the lifespan, and nearly 50% of the prevalence of dementia could be potentially attributed to the combination of two or three of the socioeconomic adversities investigated.
CONCLUSIONS: Public policies aimed at improving education, occupational skills and income could potentially have a role in primary prevention of dementia. Governments should address this issue in a purposeful and systematic way.