Category: Parkinson's Disease: Non-Motor Symptoms
Objective: To develop an objective non-verbal non-task-dependent olfactory test for PD detection.
Background: Olfactory decline may precede motor symptoms by several years or decades in Parkinson’s disease (PD). The olfactory decline in PD can be measured using various standard olfactory tests, such as UPSIT and Sniffin’ Sticks. However, such tests require full cooperation of the patient, and are sensitive to the patient’s ability to report their subjective experience.
Method: We relied on the “sniff response”, namely the automatic modulation of nasal airflow to account for odorant properties. We measured nasal airflow in response to presentation of pleasant (Citral molecule, CAS 5392-40-5, by Sigma-Aldrich), unpleasant (‘Asafoetida’ scent by DreamAir or Skatole molecule, CAS 83-34-1, by Sigma-Aldrich) and blank (empty jar) odor stimuli. Healthy participants typically reduce sniff vigor in response to unpleasant odors.
Results: We measured the sniff response of 30 PD patients (3W, mean age = 66.5 ± 7.13 years, MDS UPDRS total score = 54.4 ± 22.3, disease duration = 6.3 ± 5.7 years, MoCA score = 24.65 ± 4.15, 4 right-handed) and 32 matched healthy controls (4W, mean age = 64.5 ± 7.53 years, MoCA score = 25.8 ± 2.0, 5 right-handed). We found that whereas healthy participants modulated sniff vigor in accordance with odorant valence, PD patients did not (Repeated measures ANOVA, F1,59 = 8.27, P = .006). Post-hoc analysis using Bonferroni correction revealed that only the healthy participants reduced sniff duration in response to unpleasant odorants (Healthy: mean difference: 0.155, t = 4.6, Pbonf < .001; PD: mean difference: .013, t = 0.37, P = NS). This difference allowed for 74% PD classification based on the sniff response alone (SVM linear classifier, leave-one-out cross validation). Finally, independent of the sniff-response, sniff inhale volume was correlated with the motor disease severity (MDS UPDRS part III, r = -0.38, P = .039).
Conclusion: These results imply a potential novel biomarker for PD detection.
To cite this abstract in AMA style:
M. Andelman-Gur, N. Hezi, A. Ezra, J. Zitser, T. Gurevich, N. Sobel. Olfactory sniffing is altered in patients with Parkinson’s disease [abstract]. Mov Disord. 2023; 38 (suppl 1). https://www.mdsabstracts.org/abstract/olfactory-sniffing-is-altered-in-patients-with-parkinsons-disease/. Accessed June 15, 2025.« Back to 2023 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/olfactory-sniffing-is-altered-in-patients-with-parkinsons-disease/