We also found that the presence of APOE ε4 allele was not significantly correlated with the age at visit, the age at onset, scores of MDS-UPDRS III, H&Y stage, ADL, MMSE, MOCA and NPI, as well as the presences of fluctuating cognition, VH, parkinsonism and RBD in both groups, except for the scores of MoCA-language (r = − 0.264, p = 0.016) in DLB cases and MMSE-registration (r = − 0.216, p = 0.038) in PDD cases (Additional file, Table S2). This evidence concerns the gene APOE and Parkinson disease.