Figure 2.

Effect of the COMT Val¹⁵⁸Met and DRD2 C⁹⁵⁷T genotypes on cognitive decline in Parkinson's disease. Kaplan‐Meier plots showing the incidence of cognitive decline in relation to COMT (A–C) and DRD2 (D–F) genotype. The specific incidence of PD‐MCI and PDD (B, C, E, and F) is shown here only for the patients who had a normal cognitive function at baseline (n = 80). PD, Parkinson's disease; COMT, catechol‐O‐methyltransferase; DRD2, dopamine receptor D2; MCI, mild cognitive impairment; PDD, Parkinson's disease dementia