Book-oriented environment in childhood and current cognitive performance among old-aged europeans

Introduction: Identifying early-life factors that protect against compromised late-life cognition is of great public health interest. We aimed to explore the associations between book-oriented environment in childhood and late-life cognitive performance in the Survey of Health, Ageing and Retirement in Europe (SHARE). Methods: The sample included 8,239 individuals aged ≥65 years (N = 8,239) free of stroke, Parkinson's disease, or Alzheimer's disease, who participated in both waves 4 (2011) and 5 (2013) of SHARE. Book-oriented environment was assessed by the self-reported home library size during childhood. Cognitive performance was assessed using tests of memory and verbal fluency. Covariates included education and measures of current health, lifestyle, and financial status. Additionally, interactions with age and education were assessed. Results: After controlling for potential confounders, having large home libraries was related to better performance on the immediate and delayed memory (β = 0.11 ± 0.02, p < 0.001; β = 0.13 ± 0.02, p < 0.001) and the verbal fluency tests (β = 0.14 ± 0.06, p < 0.001) and to a lesser decline in these domains (β = 0.08 ± 0.01, p < 0.001; β = 0.09 ± 0.02, p < 0.001; and β = 0.09 ± 0.06, p < 0.001, respectively). Significant interactions were observed between library size and age such that larger home library was more strongly associated with improved immediate memory (p = 0.016), delayed memory (p < 0.001), and verbal fluency (p = 0.003) and with less cognitive decline (p = 0.013, p < 0.001, and p = 0.095, respectively) among the younger-old (<80 years) compared to the oldest-old (≥80 years) participants. No effect modification by education was observed. Conclusions: These findings suggest that early-life book-oriented environment may be important in shaping cognitive aging.