Association between Depression and Physical Fitness, Body Fatness and Serum Vitamin D in Elderly Population

Background: This study examined the association of depression with functional physical fitness, body fatness, and serum vitamin D in elderly persons. Methods: This was a cross sectional study involving 21 men with mean age of 75.4 ± 6.8 years and 96 women with mean age of 75.0 ± 6.8 years. Body mass index, percent body fat, and waist circumference were measured according to a standardized protocol. Functional physical fitness including strength, cardiorespiratory endurance, agility, dynamic balance and flexibility was measured in accordance to a standardized fitness assessment manual. Serum levels of vitamin D, lipoprotein lipids, fasting glucose and insulin were measured with standardized procedures. Korean form of Geriatric Depression Scale (K-GDS) was used to assess depression level and status. Pearson correlation analyses were used to calculate bivariate correlations between measured variables. Multiple linear regression analyses were used to identify any independent predictors for K-GDS-based depression score. Results: Depression score was significantly and inversely associated with functional physical fitness including strength (P < 0.001), cardiorespiratory endurance (P < 0.001), agility (P = 0.002) and dynamic balance (P < 0.001). A similar trend in correlation was observed between depression and serum vitamin D level. Multiple linear regression analyses showed that strength (P < 0.001), cardiorespiratory endurance (P = 0.005), and percent body fat (P = 0.045) were significant independent predictors of depression in this study population. Conclusion: The finding of the study suggest that fitness promotion along with a healthy diet habit should be a key component of intervention against depression in elderly persons.