Examining the heterogeneity by employment status in dynamics between BMI and cognition: a longitudinal cohort study of the Korean aging population

Purpose: This study investigated the potential heterogeneity by employment status in the relationship between body mass index (BMI) trajectory and cognitive function among an aging population. Methods: We analyzed 2010-2018 cohort data from the Korean Longitudinal Study of Aging involving 4889 individuals aged over 45. We used statistical techniques of quadratic terms, interaction terms, time -invariant unobserved fixed effects, and time-lag effects to estimate the dynamic and interactive relationships among study variables. Results: The effect of BMI on cognitive function was heterogeneous based on employment status. For the nonemployed group, the impact of BMI on cognitive function showed an inverted U-shape with a turning point (BMI 25); a higher BMI (up to 25) was associated with higher cognitive function, but further increases beyond this threshold led to decreased cognitive function. For the employed group, however, the impact of BMI on cognitive function was nonsignificant. The nonlinear effect of BMI on cognitive function for the nonemployed group was robust across various subgroups and specifications. Conclusions: The findings highlight the risk of obesity (BMI >= 25) on cognitive decline, particularly among nonemployed individuals. This illuminates the critical role of labor activity in regulating the impact of BMI on cognitive function among an aging population. (c) 2023 Elsevier Inc. All rights reserved.

Automated summary

This study investigated the relationship between body mass index (BMI) trajectory and cognitive function among an aging population, specifically considering the heterogeneity by employment status. The findings suggest that the impact of BMI on cognitive function varies based on employment status, with a non-linear effect observed in the nonemployed group. Obesity (BMI >= 25) was found to be a risk factor for cognitive decline, particularly in nonemployed individuals. Labor activity plays a critical role in regulating the impact of BMI on cognitive function.