Longitudinal association between muscle strength and depression in middle-aged and older adults: A 7-year prospective cohort study in China.

BACKGROUND: Evidence regarding the associations between muscle strength in different parts of the body and depression is lacking. This study examined whether poor muscle strength is associated with a higher incidence of depression in a large cohort of middle-aged and older adults. METHODS: In total, 5,228 middle-aged and older adults from the China Health and Retirement Longitudinal Study without depression at baseline were followed for 7 years. Their demographic characteristics, chronic diseases and lifestyle behaviors were assessed. After adjusting for relevant variables, a Cox regression was used to determine the relationship between muscle strength and incident depression. RESULTS: Over 32,544 person-years of follow-up, 1,490 participants developed depression. Low muscle strength at baseline was associated with a higher 7-year incident of depression, even after excluding those who developed depression within 2 years. After adjusting for confounding factors, it was found that a higher baseline relative handgrip strength was a protective factor against depression (HR [95% CI]=0.575 [0.430-0.768] for the lowest quartile vs. the highest quartile; p<0.001). Longer times on the 5TSTS test were a risk factor for depression (HR [95% CI]=1.321 [1.077-1.621] for the lowest quartile vs. the highest quartile; p = 0.007). When the strengths of the upper and lower limbs were considered together, the hazard ratio for depression in people with relatively greater muscle strength was 0.463 (95% CI=0.307-0.699; p<0.001). CONCLUSIONS: Muscle strength could be predictive of depression, and the combined measurement of upper and lower limb muscle strength can improve the predictive ability.

The association between pulmonary function and depression in middle-aged and elderly people in China: The role of cognitive ability and sleep time.

BACKGROUND: Depression is a common mental disorder in middle-aged and elderly people, which seriously affects their physical health and life quality.So far, whether pulmonary function is a factor in depression has not been tested.The purpose of this study was to test whether pulmonary function was independently associated with depression and to assess the effects of cognitive ability and sleep time on this association. METHODS: In this analysis, 5,235 participants from the Chinese Longitudinal Study of Health and Retirement were included. Participants were registered in 2015 and followed up in 2018. The relationship between pulmonary function and depression was estimated by binary logistic regression model. The mediated role of cognitive ability was examined by intermediary analysis, and the interaction between pulmonary function and sleep time on depression was discussed. RESULTS: After adjusting for confounding factors, it was found that higher baseline pulmonary function was the protective factor of depression (OR [95%CI]=0.524 [0.394-0.697] for the lowest quantile vs the highest quantile). Cognitive ability explained 14.55% of the association between pulmonary function and depression, pulmonary function and sleep time on the effects of depression have a combined interaction, RERI (95%CI) = 0.545 (0.053-1.038). CONCLUSIONS: High baseline pulmonary function is independently associated with a lower risk of depression, which is partly mediated by cognitive ability. Pulmonary function and sleep time have synergy with the effects of depression. These findings show that pulmonary function, cognitive ability and sleep time are reliable predictors of depression.

The relationships between step count and all-cause mortality and cardiovascular events: A dose-response meta-analysis.

BACKGROUND: A goal of 10,000 steps per day is widely advocated, but there is little evidence to support that goal. Our purpose was to examine the dose-response relationships between step count and all-cause mortality and cardiovascular disease risk. METHODS: Cochrane Central Register of Controlled Trials, EMBASE, OVID, PubMed, Scopus, and Web of Science databases were systematically searched for studies published before July 9, 2021, that evaluated the association between daily steps and at least 1 outcome. RESULTS: Sixteen publications (12 related to all-cause mortality, 5 related to cardiovascular disease; and 1 article contained 2 outcomes: both all-cause death and cardiovascular events) were eligible for inclusion in the meta-analysis. There was evidence of a nonlinear dose-response relationship between step count and risk of all-cause mortality or cardiovascular disease (p = 0.002 and p = 0.014 for nonlinearity, respectively). When we restricted the analyses to accelerometer-based studies, the third quartile had a 40.36% lower risk of all-cause mortality and a 35.05% lower risk of cardiovascular event than the first quartile (all-cause mortality: Q1 = 4183 steps/day, Q3 = 8959 steps/day; cardiovascular event: Q1 = 3500 steps/day, Q3 = 9500 steps/day; respectively). CONCLUSION: Our meta-analysis suggests inverse associations between higher step count and risk of premature death and cardiovascular events in middle-aged and older adults, with nonlinear dose-response patterns.