Association of Relative Fat Mass with Incident Depressive Symptoms among Older Adults: A 14-Year Analysis of the ELSA and HRS Cohorts

Abstract

Objective

Not known is whether relative fat mass (RFM)—a height- and waist-based estimator of total adiposity—predicts late-life depressive symptoms better than conventional anthropometrics.

Methods

This study analyzed harmonized data from two nationally representative aging cohorts: the English Longitudinal Study of Ageing (ELSA) and the US Health and Retirement Study (HRS). Adults ≥50 years without baseline depressive symptoms (CES-D-8 <3) and with valid anthropometrics and covariates were followed biennially for up to 14 years (ELSA n = 4176; HRS n = 5054). RFM was computed from measured height and waist circumference and examined continuously (each 1–standard deviation [SD] increase) and by tertiles. Incident depressive symptoms were defined as CES-D-8 ≥3 at follow-up. Cox models estimated hazard ratios (HR) with progressive adjustment. Dose–response was assessed using restricted cubic splines. Predictive performance was compared with body mass index (BMI) and waist circumference (WC) via time-dependent AUCs. Sensitivity analyses used multiple imputation and propensity-score matching.

Results

Over a mean of 8.60 years (ELSA) and 8.57 years (HRS), 1467 and 1769 participants developed incident depressive symptoms. Higher baseline RFM predicted incident depressive symptoms in both cohorts (for each 1–SD, Model 3: ELSA HR = 1.15, 95% CI = 1.06-1.25; HRS HR = 1.10, 95% CI = 1.05-1.16). Compared with low RFM, high RFM remained associated with higher risk (ELSA HR = 1.37, 95% CI = 1.12-1.67; HRS HR = 1.29, 95% CI = 1.14-1.46). Restricted cubic splines suggested a J-shaped association. Time-dependent AUCs showed RFM consistently outperformed BMI and WC across follow-up. Findings were robust in multiple imputation and propensity-matched analyses.

Conclusions

In two national cohorts of older adults, higher RFM was prospectively associated with incident depressive symptoms and demonstrated superior time-varying discrimination compared with BMI and WC, supporting RFM as a pragmatic tool for late-life depressive symptoms risk stratification.