Research Square · Oct 28, 2026
Between-person and within-person associations among depressive symptoms, global cognition, and grip strength in older Korean adults: A 12-year longitudinal study
By Jung MS, Park M, Lee AR et al.
Depressive symptoms, cognitive performance, and grip strength often co-occur in later life, but longitudinal associations may reflect stable between-person differences rather than within-person change. We analyzed seven biennial waves (2006–2018) of the Korean Longitudinal Study of Ageing, including 4,164 community-dwelling adults aged 65 years or older at baseline. A trivariate random-intercept cross-lagged panel model separated stable between-person differences from wave-specific within-person deviations in depressive symptoms, Mini-Mental State Examination scores, and grip strength. Adjusted random-intercept correlations were moderate (|r| = 0.31–0.44). Cross-lagged associations varied across intervals (robust Δχ²(30) = 100.24, p < 0.001), and 10 of 31 unique estimates met the false discovery rate criterion. Depressive-symptom elevations preceded lower cognition in two intervals and weaker grip in three; higher cognition preceded fewer depressive symptoms in two intervals, and stronger grip preceded fewer depressive symptoms once. Grip strength did not consistently predict subsequent cognition. All 10 primary estimates retained their direction in sensitivity analyses, although statistical significance was attenuated using the harmonized depressive-symptom score. These findings indicate broad stable cross-domain concordance but selective, time-varying within-person coupling, highlighting the importance of distinguishing persistent vulnerability from changes relative to an individual’s usual level.