High prevalence of parkinsonism in patients with MCI or mild Alzheimer's disease

Abstract Introduction The objective of this study was to examine the prevalence of the coexistence of parkinsonism in patients with mild cognitive impairment (MCI) or mild Alzheimer's disease (AD). Methods Outpatients were evaluated with Mini–Mental State Examination, Clinical Dementia Rating Scale, NIA-AA criteria, MRI, and 123 I-IMP SPECT (3D-SSP). Parkinsonism in patients diagnosed with MCI (Mini–Mental State Examination ≥24, n = 63) or mild AD (Mini–Mental State Examination 20–23, n = 43) was examined using the Unified Parkinson's Disease Rating Scale–III and 123 I-FP-CIT dopamine transporter SPECT. Results One hundred six patients (60–97 years) were enrolled. Fifty-six patients (52.8%) were diagnosed as having concomitant parkinsonism with rigidity and resting tremor and dopamine transporter reduction in the basal ganglia. The mean (SD) age (n = 56) was 80.6 (6.1) years, significantly older than patients without parkinsonism [77.6 (7.0) years, n = 50] ( P Conclusion The prevalence rate of the coexistence of mild parkinsonism in MCI or mild AD may be higher than previously recognized.