The present study was adjusted for the covariates/confounders considered to fully explore the association between serum ALP and risk of depression in adults, and the findings suggest that the association between serum ALP and depression was consistent across these subgroups: age (<60, or ≥ 60 years), gender (male or female), BMI (<25.0, 25.0–29.9, or ≥ 30.0 kg/m2), smoking status (smoker or non-smoker), albumin (<40, or ≥ 40 g/L), AST (<30 or ≥ 30 U/L), TG (<1.7, or ≥ 1.7 mmol/L), and diabetes (yes or no). Here, ALB is linked to major depressive disorder.