The odor stick identification test for Japanese differentiates Parkinson's disease from multiple system atrophy and progressive supra nuclear palsy

We assessed the olfactory function using the OSIT-J test in 94 Japanese patients with idiopathic PD, 15 with MSA-P, 7 with PSP, and 29 age-matched control subjects.The mean ± SD score of OSIT-J in patients with PD (4.4 ± 2.9) was significantly lower than in patients with MSA-P (8.7 ± 2.2, P < 0.0001), PSP (7.6 ± 2.2, P < 0.0057), and control subjects (10.5 ± 1.3, P < 0.0001). The area under the curve (AUC) of receiver operating characteristic (ROC) to discriminate PD from normal control using OSIT-J scores was 0.97 (95% confidence interval, 0.95-1.00), from MSA-P 0.87 (0.80-0.95), and from PSP 0.81 (0.66-0.96).The OSIT-J is a potentially useful clinical test not only for detection of olfactory deficit in PD but also for differentiating PD from MSA-P and PSP.Olfactory dysfunction is recognized as a non-motor symptom in idiopathic Parkinson's disease (PD), and is a maker for preclinical diagnosis of PD based on the appearance of pathological changes in the olfactory system before the development of motor symptoms [1]. A recent study indicated that the early appearance of impaired olfaction prior to other clinical features of PD could be a useful screening tool to detect those at high risk for the development of PD in later life [2]. In fact, several Japanese researchers employ the 12-odorant test, the Odor Stick Identification Test for Japanese (OSIT-J) in the clinical testing of PD [3-5] and have reported their findings of dysosmia and that it did not correlate with motor function, disease duration, or medication, indicating that OSIT-J scores are independent of all other measures in PD [3,4]. In addition to the practice in Japan, the results of the University of Pennsylvania 12 smell identification test (UPSIT), which is also a smell identification test [6-8], indicate that OSIT-J is a short and simple noninvasive test that is potentially useful clinically for detecting early-stage PD.The diagnosis of PD is based on clinical criteria, the accuracy of such diagnosis