Longitudinal association between handgrip strength and depressive symptoms in middle-aged and older Chinese adults: mediating role of functional limitation - Liu, Yanchang; Cui, Junling; Luo, Xin; Wang, Zhuzhu; Shen, Ziyi; Fang, Yan; Li, Chengcheng; Hong, Jingfang (Frontiers in Public Health, 2025)