Late, but not too late, is better than never: late‐life literacy is not associated with lower prevalence of dementia and cognitive impairment no dementia

Abstract

AbstractBackgroundEducation is a major modifiable risk factor for dementia and is usually considered an early‐life intervention. However, low‐ and middle‐income countries usually have high rates of illiteracy among older adults, and some became literate after childhood. Therefore, we aimed to investigate whether there were any associations between the age of literacy with the prevalence of cognitive impairment no dementia (CIND) and dementia, compared to illiteracy, regardless of the educational attainment.MethodWe used baseline data from the Brazilian Longitudinal Study of Aging (ELSI‐Brazil), a population‐based nationally representative cohort of people aged 50 years or older, and the first Health and Retirement Studies (HRS) partner study in South America. For this study, we restricted our analysis to those aged 60 years or older, who had been classified as cognitively normal, CIND, or dementia. Participants were stratified into five groups: four according to their age when started schooling (early‐life literacy (EL) (<11 years), adolescent literacy (AdL) (11‐19 years), adulthood literacy (AhL) (20‐59 years) and late‐life literacy (LL) (≥60 years)) and illiteracy (IL). CIND and dementia classification prevalence ratios (PR) according to literacy status were assessed using Poisson regression, and adjusted for sociodemographic (age, sex/gender, educational attainment, race/ethnicity) and clinical confounders (memory complain, depressive symptoms, heavy drinking, smoking status, hypertension, and diabetes).ResultOur final sample comprised 5,244 older adults (mean age 70.1±7.8 years, mean education 4.6±4.4 years, 60% female, 55% Black/Brown, 6% with dementia and 8% with CIND) (Table 1). Fifteen percent of the sample started their literacy after childhood, and 21% remained illiterate. EL and (PR = 0.22, 95%CI = 0.09;0.53) and AdL (PR = 0.42, 95%CI = 0.18;0.98) groups had lower dementia prevalence compared to IL group (Table 2). However, there was no prevalence difference between IL and those who started literacy after adolescence.ConclusionWe found a lower prevalence of dementia among participants with early‐life and adolescent literacy compared to illiteracy. Adulthood and late‐life literacy were not associated with lower dementia prevalence. Literacy after childhood might have same beneficial impact if it is not started too later in life. Further studies should be conducted to better understand the impact of late‐life literacy interventions on reducing dementia risk.