Knee Extensor Muscle Strength And The Depressive Status Among Older Japanese Women: A Cross-sectional Study

Abstract

Depression is commonly regarded as a crucial public health issue because of its detrimental effect on increased mortality and its huge economic burden. Although physical function is generally related depression symptoms, it remains controversial whether lower-extremity muscle strength is a risk factor for geriatric depression symptoms among older women. PURPOSE: To investigate the cross-sectional association between knee extensor muscle strength and geriatric depressive status. METHODS: A cross-sectional study was conducted on 1258 older Japanese women (mean age 71.8 years [standard deviation: 4.3]) who lived in the metropolitan area of Tokyo and were recruited from the basic resident register. They completed an isometric knee extensor muscle strength measurement (newton per kilogram of body weight) and responded to an interview-based questionnaire on their smoking and alcohol consumption habits, history of lifestyle-related diseases (hypertension, stroke, heart disease, diabetes, dyslipidemia, osteoporosis, and cancer), working conditions, hobbies or lessons, participation in volunteer work, living alone status, sleep time, and dietary pattern. Depressive symptoms were defined as a 15-item Geriatric Depression Scale (GDS) score ≥ 6 points. Multivariable odds ratios (OR) and 95 percent confidence intervals (CI) for the presence of depressive symptoms were obtained using a logistic regression model after adjusting for age, body mass index, and the above-mentioned confounding factors. RESULTS: A total of 112 women (8.9%) had geriatric depressive symptoms. After adjusting for various covariates, OR (95% CI) of the depressive symptoms was 1.11 (0.66, 1.89) for the second quartile of knee extensor muscle strength per body weight, 0.38 (0.18, 0.73) for the third quartile and 0.70 (0.38, 1.29) for the fourth quartile, using the first quartile as a reference category (p for trend = 0.04). CONCLUSIONS: Our findings suggest that low muscle strength is associated with geriatric depressive symptoms in older Japanese women. We need to further explore its longitudinal association in the future.