Objective: The purpose of this study was to determine the relationship between clinical variables (motor and non-motor functions), duration, stage and severity of disease with olfactory dysfunction in PD patients.

Background: Olfactory impairment (OI) is one of the non-motor features of Parkinson’s disease (PD). The high prevalence, persistence throughout disease, and ease of olfactory testing has fostered interest in the use of olfaction as a biomarker in PD.

Methods: 118 patients with clinical diagnosis of PD (UK PD Society Brain Bank criteria:, mean age 67.62 ± 9.21 years, mean H&Y: 1.92 ± 0.71, mean disease duration 6.49 ± 5.52 years) and without dementia were evaluated at the outpatient clinic of Movement Disorders Center of Perugia. Odor identification ability was tested using Italian Olfactory Identification Test (33-testers), recently designed for the Italian population. All patients (assessed during ‘on’-state), underwent a detailed neurological evaluation for the clinical characteristics examined. An interview was performed to establish autonomic function, depressive symptoms, sleep disturbances (nighttime sleep, daytime sleepiness and sleep quality), respiratory disturbances.

Results: Of the 118 PD patients 85% were hyposmic and 15% normosmic. There was a statistically significant correlation between olfactory impairment and motor features (body bradykinesia and hypokinesia, posture, freezing of gait and dyskinesias) as well as with disease duration. The non motor parameters examined were not correlated with IOIT scores. In this group of patients using the IOIT we previously identified 3 odors (basil, coffee, pineapple) that patients most frequently failed to recognize.

Conclusions: The relationship between hyposmia and motor features as well as with disease duration suggests that the olfactory testing, also in association with other biomarkers, may be a useful marker to identify patients at risk for major complications correlated to PD (such as freezing of gait and dyskinesias). This test might also provide prognostic information possibly allowing in the future to better target these patients with disease-modifying therapies that might delay or mitigate these devastating effects.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/italian-olfactory-identification-test-ioit-scores-correlates-with-clinical-features-in-parkinsons-disease/