Odor Identification Function Differs between Vascular Parkinson ism and Akinetic-Type Parkinson's Disease

Abstract

Objective: Main clinical features of vascular parkinsonism (VP) are rigidity, fixed face, and short stepping gait. VP remains difficult to diagnose based on clinical features from patients with Parkinson’s disease (PD) without rest tremor. Olfactory dysfunction is a non-motor symptom in idiopathic PD. We investigated whether olfactory function can distinguish VP from PD. Method: Participants were comprised of 13 patients with VP, 40 non-demented patients with akinetic-type PD, and 40 age-matched controls. Olfactory function was examined using the Odor Stick Identification Test for Japanese (OSIT-J), which evaluates the detection of 12 odorants familiar to Japanese participants. Results: Corrected odor identification scores in OSIT-J were 8.2 ± 1.5 (mean ± SD) points in patients with VP, 3.2 ± 2.5 in PD patients, and 7.1 ± 3.0 in normal subjects. These were significantly higher in VP than those in PD patients (p<0.001), but were not different from those in normal subjects. Conclusion: The olfactory identification test is non-invasive, convenient, and useful to distinguish VP from PD as a screening test.