EARLY LIFE AND COGNITIVE RESERVE: ASSOCIATIONS WITH DEMENTIA AMONG OLDER PEOPLE IN CENTRAL AFRICA IN THE EPIDEMCA POPULATION-BASED STUDY

Abstract

Some evidence suggests that early life experiences, during the brain development and maturation period, influence the risk of developing dementia in late life. Indicators of brain development, early life nutrition, stressful life events as well as education and occupational attainment have shown associations with the prevalence or the incidence of dementia. However the evidence was mainly established in high-income settings. The aim of this study is to investigate the association between early life and cognitive reserve indicators with dementia in sub-Saharan African countries. A multicentre population-based study was carried out in Central African Republic and Republic of Congo between 2011 and 2012 including both urban and rural sites. Participants aged ≥65 years old were interviewed using a structured questionnaire and underwent a physical examination. Leg length (index of brain development), skull circumference (index of early life nutrition), early life events (residence, stressful life events), education, and occupational attainment data were collected. Participants in Congo were followed up for 2 years. DSM-IV and NINCDS-ADRDA criteria were required for dementia and Alzheimer's disease diagnoses at baseline and follow-up. The effect of covariates on dementia prevalence and incidence were modelled using Poisson and competing-risk regression models. At baseline, 2002 participants were included in both countries. Overall, mean age was 73.3 ± 6.7 years, sex-ratio M/F was 0.62 and 135 were diagnosed with dementia. Over 68% of the participants had no formal education, half were farmer/breeder (49.2%) and 11.6% reported a full-time occupation. Regarding early life, only 18.9% had never lived a stressful event during their childhood and 20.0% were born in the countryside. After adjustment on site, age, and sex, only a smaller skull circumference was significantly associated with dementia prevalence (PR=2.2 (95%CI:1.1–4.4). Interactions between early life and cognitive reserve indicators and sex or study area, as well as the effects on dementia incidence within the Congolese participants will be presented in details. Preliminary results support the effect of early life nutrition on dementia prevalence in late-life in Central Africa. These results will add to the scarce evidence on early life, cognitive reserve and dementia in sub-Saharan Africa.