Executive Dysfunction in Parkinson’s Disease

Definition of Participants

Of 146 patients consecutively diagnosed with sporadic form PD at the neurology clinic of our hospital, 96 gave informed written consent to participate in this study. The clinical diagnosis of sporadic PD was made according to the UK PD Brain Bank criteria (Gibb, W. R. & Lees, A. J., 1988). Based on clinical features and neuroradiological findings from brain computed tomography (CT) and magnetic resonance imaging (MRI) at later than 12 months post-onset, we excluded other forms of parkinsonism, which included (1) dementia with Lewy bodies (DLB) (Geser, F. et al., 2005; McKeith, I. G. et al., 1996), (2) drug-induced parkinsonism, (3) vascular parkinsonism, and (4) atypical parkinsonism with absent or minimal responses to anti-parkinsonian drugs. The subjects included in the study had thus exhibited good responses to anti-parkinsonian drugs and did not have a history of visual hallucinations or fluctuations in cognitive ability suggestive of the clinical diagnosis of DLB at 12 months post-onset.