APOE and Parkinson disease: Moreover, the residual of the model predictions (Fig. 2E) was not significantly correlated with sex, age, APOE epsilon 4 allele status, or Levodopa dosage; however, the model’s residuals were significantly correlated with PD vs. PDD or DLB vs. PD/PDD, indicating that the model performed equally well across these major variables except within the LBD diagnosis group.