ALB and major depressive disorder: The results of multivariate logistic regression analysis showed that the independent factors of cognitive frailty were age (P < 0.001), education level (P = 0.010), nutritional status (P = 0.001), serum albumin level (P = 0.010), calf circumference (P = 0.024), and social support level (P < 0.001) in the elderly group and comorbidity status (P = 0.037), education level (P < 0.001), nutritional status (P = 0.008), serum creatinine level (P = 0.001), waist circumference (P < 0.001), and depression (P = 0.006) in the middle-young group.