PD patients who have a higher normalized serpinA1 signal of the most acidic isoform (peak 0) than the selected 2nd cut-off value of 6.44 * 10−3 have a 6.4 fold higher risk to be associated with dementia compared to PD patients with a normalized serpinA1 signal below this cut-off (Fig. 4B). The gene discussed is SERPINA1; the disease is Parkinson disease.