Background: Few studies have examined the associations between changes in depressive symptoms and handgrip strength in older people. This study aimed to examine the magnitude of the association between depressive symptoms over 2 years and weak handgrip strength on the 4 years of follow-up.
Methods: We conducted a longitudinal study using data from the English Longitudinal Study of Aging, a nationally representative panel survey of older adults in England. Data were derived from waves 4 (2008-2009), 5 (2010-2011), and 6 (2012-2013). A total of 5,080 participants were included in the analysis. Depressive symptoms were dichotomized using the eight-item Center for Epidemiological Studies Depression Scale in waves 4 and 5 and were regarded as the exposure. Handgrip strength measurements objectively measured in wave 6 were dichotomized according to the 25th percentile of the British norm and used as the outcome. The targeted maximum likelihood estimation model was utilized to assess time-variant depressive symptoms on handgrip strength, adjusted for time-variant and time-invariant covariates.
Results: The maintenance of non-depressive symptoms (relative risk [RR], 0.72; 95% confidence interval [CI], 0.59-0.87) or improvement of depressive symptoms (RR, 0.71; 95% CI, 0.55-0.91) had a protective effect on weak handgrip strength compared with the persistence of depressive symptoms.
Limitation: This study is not a randomized control trial but a longitudinal observational study, indicating that our study finding may still have been affected by unknown confounders.
Conclusion: Our findings suggest the importance of managing depressive symptoms to prevent poor physical function.
Keywords: Depression; Mental health; Muscle weakness; Physical function; Targeted maximum likelihood estimation.
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