In a multiple linear regression model (Table 3, Figure 1), no associations with change in HDRS score were found for demographic (age, PD duration, PD subtypes, age of onset, history of depression, and living alone), treatment (levodopa dose at baseline, with or without use of antidepressant, acetylcholinesterase inhibitors, or dopamine agonist at baseline), and assessment (baseline MMSE and change of UPDRS-III scale). This evidence concerns the gene ACHE and major depressive disorder.