Although PD patients harboring COMT rs4680 seemed to have a reduced risk of developing depression, the minor COMT rs4680 and TH rs6356 alleles exerted a protective effect on cognitive function in PD patients, and DBH rs1611115 tended to increase the risk for impaired cognition in PD in the subgroup analysis. The gene discussed is COMT; the disease is depressive symptom measurement.