Longitudinal bidirectional relations between self-care ability of daily living and depressive symptoms among Chinese older adults: The mediating role of parent-child relationship

Technical Summary: Longitudinal Bidirectional Relations Between Self-Care Ability and Depressive Symptoms in Chinese Older Adults

Problem Statement
While existing literature has extensively explored the impact of Activities of Daily Living (ADL) on depressive symptoms (a "body-to-mind" perspective), there is a scarcity of longitudinal research examining the reverse causal pathway (a "mind-to-body" perspective) and the bidirectional dynamics between Instrumental Activities of Daily Living (IADL) and depressive symptoms. Furthermore, the mediating role of the parent-child relationship in these interplays remains under-investigated, particularly regarding how family dynamics might buffer or exacerbate the relationship between functional decline and mental health in the context of China's rapidly aging society.

Methodology
This study utilized a longitudinal design based on data from the China Health and Retirement Longitudinal Study (CHARLS), covering three waves: 2015 (T1), 2018 (T2), and 2020 (T3). The final sample consisted of 2,877 Chinese older adults (aged 60+) who had complete data across all three waves.

• Variables:
  • Predictors/Outcomes: Self-care ability was measured using ADL (6 items) and IADL (5 items) scales, with higher scores indicating greater disability. Depressive symptoms were assessed using the Center for Epidemiological Studies-Depression Scale (CESD-10).
  • Mediator: Parent-child relationship was measured by satisfaction with the rapport with offspring (1–5 scale).
  • Covariates: Age, gender, residence, marital status, education, self-rated physical health, and log-transformed personal income.
• Statistical Analysis:
  • Fixed-Effect Models: Used to estimate the influence of self-care ability on depressive symptoms while controlling for unobserved time-invariant individual characteristics.
  • Cross-Lagged Panel Models (CLPM): Employed to analyze the longitudinal bidirectional causal relationships between self-care abilities (ADL, IADL, and a composite "Degree of Disability"), depressive symptoms, and parent-child relationships. This model assessed both stability effects (autoregressive) and cross-lagged effects (reciprocal influence over time).
  • Software: STATA 15.0 was used for all analyses, with bootstrapping (16,000 iterations) to determine 95% confidence intervals.

Key Results

1. Descriptive Trends: From 2015 to 2020, the sample showed a decline in self-care ability (increasing ADL and IADL scores) and an increase in depressive symptoms (CESD scores). Concurrently, the proportion of participants reporting "fully satisfied" parent-child relationships decreased.
2. Bidirectional Relationships:
   • Self-Care and Depression: A significant positive bidirectional relationship was found between self-care abilities (both ADL and IADL) and depressive symptoms. Impairments in self-care predicted higher subsequent depressive symptoms, and higher depressive symptoms predicted subsequent declines in self-care ability.
   • Parent-Child Relationship and Depression: A significant bidirectional relationship existed between parent-child relationships and depressive symptoms. Poorer relationships predicted higher depression, and higher depression predicted poorer relationships in subsequent waves.
3. Mediating Effects:
   • ADL Pathway: The longitudinal bidirectional mediating effect of the parent-child relationship between ADL and depressive symptoms was not significant.
   • IADL Pathway: The parent-child relationship served as a significant longitudinal bidirectional mediator between IADL and depressive symptoms. Specifically, IADL influenced parent-child relationships, which in turn influenced depressive symptoms, and vice versa.

Key Contributions

• Bidirectional Causality: The study provides empirical evidence for the reciprocal nature of the relationship between daily self-care abilities and depressive symptoms, moving beyond cross-sectional correlations to establish temporal precedence in both directions.
• Differentiation of ADL and IADL: The research highlights a critical distinction between basic self-care (ADL) and instrumental self-care (IADL). While both are linked to depression, only the IADL-depression pathway is significantly mediated by the parent-child relationship.
• Mediating Mechanism: It is the first study to systematically explore the longitudinal bidirectional mediating role of parent-child relationships in the interplay between self-care abilities and depressive symptoms among Chinese older adults.

Significance and Claims
The authors claim that these findings offer a nuanced understanding of the "body-mind" and "mind-body" interplay in aging. The study suggests that interventions should be tailored based on the specific type of functional impairment:

• For older adults with impaired IADL but intact ADL, interventions should focus on strengthening family interactions and parent-child relationships, as these serve as a protective mediator against depression.
• For older adults with impaired ADL, interventions should prioritize psychological counseling and support services, as the parent-child relationship does not significantly mediate the impact of basic physical disability on depression.

The paper concludes that these insights provide a basis for policymakers to design targeted strategies that promote family communication to enhance mental health and self-care, while also ensuring that healthcare institutions provide necessary psychological support for those with severe physical functional decline. The authors acknowledge limitations regarding the reliance on self-reported data and the relatively short tracking period, suggesting that future research should incorporate objective assessments and longer longitudinal timelines.