Our MR results showed a causality of Cathepsin H levels for AD risk with positive relationship in all three tissues (β = 0.34, FDR = 1.10 × 10−4 in brain; β = 0.23, FDR = 3.23 × 10−4 in CSF; β = 0.26, FDR = 4.54 × 10−4 in plasma), indicating that higher Cathepsin H levels significantly increase AD risk. Here, CTSH is linked to Alzheimer disease.