Childhood hunger and cognitive impairment in later life among older adults in China: a nationwide case-control study using target maximum likelihood estimation

Background: Early life nutritional deprivation is associated with poor health outcomes in later life, such as cognitive impairment. Since many older Chinese adults experienced frequent hunger during childhood, we aimed to estimate its impact on late-life cognitive impairment in older adults. Methods: We included participants aged 65-99 years from the 2017-2018 wave of the Chinese Longitudinal Healthy Longevity Survey, who completed the Mini-Mental State Examination (MMSE) and reported whether they experienced childhood hunger. We classified participants based on their MMSE scores into a cognitive impairment group (case group) and a control group. We used an unmatched case-control design, with unconditional logistic regression and case-control weighted target maximum likelihood estimation (CCW-TMLE), to assess the impact of childhood hunger on late-life cognitive impairment, and conducted sensitivity analyses to evaluate robustness of the association between them. Results: Among 9,297 participants, 1,108 (11.92%) had cognitive impairment. Childhood hunger was more prevalent in the cognitive impairment group (76.62% vs. 69.48%, P < 0.001). In the full model, childhood hunger was significantly associated with a higher prevalence of cognitive impairment (odds ratio (OR) = 1.229; 95% confidence interval (CI) = 1.044-1.447, P = 0.013) compared to the non-childhood hunger group. CCW-TMLE also found that the childhood hunger group had a higher prevalence of later-life cognitive impairment (risk ratio (RR) = 1.167; 95% CI = 1.046-1.303; OR = 1.224, 95% CI = 1.063-1.410). The results of sensitivity analyses supported the robustness of the impact. Conclusions: Childhood hunger was associated with a higher prevalence of cognitive impairment in later life. The findings suggest that improving childhood nutrition and food security might be linked to a lower burden of late-life cognitive impairment, particularly in economically disadvantaged populations. However, further research is needed to establish causality.