PRPH and mild neurocognitive disorder: Based on these findings, we calculated the ROC curve for PRPH to differentiate ALS patients and MND mimics, finding an AUC of 0.846 (IC 0.791–0.902) and the best cut‐off level of PRPH at 1.06 ng/mL with a Youden index of 0.54, with a sensitivity of 0.770 and a specificity of 0.767 (Figure S5).