DEMENTIA PREVENTION IN LOW- AND MIDDLE-INCOME COUNTRIES: POPULATION ATTRIBUTABLE FRACTION FOR POTENTIALLY MODIFIABLE RISK FACTORS

Abstract

Nine potentially modifiable risk factors (less childhood education, hearing loss, smoking, hypertension, obesity, physical inactivity, social isolation, depression, and diabetes) account for 35% of worldwide dementia. Most data to calculate potentially modifiable risk factors comes from high income countries, so the impact of potentially modifiable risk factors in low- to middle-income countries (LMIC) is unknown. Two-thirds of people with dementia live in LMIC and population ageing is projected to result in a significant increase in numbers of people with dementia. We therefore calculated population attributable fractions (PAF) for dementia in the LMIC for which we could obtain population-level data, to identify potential dementia prevention targets in LMIC. We used 10/66 dementia research group cross-sectional surveys of representative populations in India, China and Latin America (Cuba, Dominican Republic, Venezuela, Mexico, Peru and Puerto Rico combined, as risk factor prevalences were similar) which used identical risk factor ascertainment methodology in each country to consider risk factors. 10/66 study representativeness was ensured by pre-defining catchment areas and then approaching all people over 65 years in that catchment area for participation. We used risk factor prevalences from 10/66 and relative risk estimates from previous meta-analyses to calculate PAFs for each risk factor. To account for individuals having overlapping risk factors, we adjusted PAF for communality between risk factors, using these figures to calculate combined PAF figures for India, China and Latin America. The combined PAF for potentially modifiable risk factors for dementia were: 40% in China (N=2162 participants); 41% in India (N=2004) and 56% in Latin America (N=12865). Less childhood education, smoking, hypertension, obesity and diabetes were more common than worldwide estimates across all three regions, leading to higher PAF. There is a large dementia prevention potential in LMIC, specifically India, China and Latin America, which is greater than in high-income countries. Less education in early life, hypertension, hearing loss, obesity and physical inactivity have particularly high PAF and may be initial targets for dementia prevention strategies.