Smell identification in Japanese Parkinson's disease patients: using the odor stick identification test for Japanese subjects.

Objective The purpose of the present study was to clarify the olfactory functions of Japanese patients with idiopathic Parkinson's disease (IPD) using the odor stick identification test for Japanese (OSIT-J). Methods Fifty-four non-demented IPD patients (33 men and 21 women), ranging in age from 43 to 81 years (69.7±8.1 years) and 50 age- and gender-matched healthy controls who reported having no olfactory complaints were enrolled. OSIT-J consisted of 12 odorants familiar to Japanese subjects. Each subject sniffed each odor that was applied to paraffin paper. Next the subject chose 1 of 6 answers: 4 pictures associated with the odors labeled with their names, one of which was correct, and 2 other ones ("unknown" and "not detected"). Results The number of correct answers was significantly lower in the IPD group (4.4±2.7) than in the normal group (8.3±2.2) (p<0.0001). Even in IPD patients who could smell normal strength odors in subjective symptom, the number of correct answers decreased. The number of correct answers was not correlated with motor function, disease duration, or medication. Conclusion The present study demonstrated that the smell identification ability of Japanese IPD patients was impaired based on the OSIT-J.