Unveiling the multifaceted nexus of subjective aging, biological aging, and chronological age: Findings from a nationally representative cohort study

Objectives: This study aims to investigate how subjective aging influences the psychological and behavioral responses of older individuals, specifically focusing on the associations between subjective aging and longitudinal changes in biological age. Methods: This is a retrospective cohort study retrieving data from the Taiwan Longitudinal Study on Aging (TLSA), over a 4-year follow-up period. Subjective aging is assessed by asking participants if they perceive themselves as old, while frailty is measured using a frailty index comprising 34 deficits from various domains. Participants are categorized into three groups based on their chronological age. The association between subjective aging and transition of biological age (as indicated by an increased frailty index) from 2011 to 2015 is examined using logistic regression models. Results: The study consisted of 2412 participants, who were categorized into middle-age (n = 1,082), young-old (n = 779), and old-old (n = 551) groups. Among them, individuals exhibiting subjective aging at baseline were more likely to be older in chronological age, female, illiterate, and unemployed, compared to those without subjective aging. The adjusted odds ratios (aORs) for the association between subjective aging and an increased biological age were 1.72 [95% CI: 0.88-3.34], 1.61 [0.77-3.37], and 1.08 [0.65-1.80], in the middle-age, youngold, and old-old groups, respectively. Discussions: No significant associations were found between changes in biological age and subjective aging across various chronological age groups. Notably, within the younger age group, a discernible trend towards an association was observed, indicating the potential age-related nuances in the complex interrelation between subjective age, biological aging, and chronological aging.