Objective: To study the discrepancy between self-reported hyposmia and the objective assessment of Sniffin’ sticks (identification subset, SS-16) in high risk of synucleinopathy and healthy controls.

Background: Hyposmia strongly predicts Parkinson’s disease (PD) phenoconversion, with a 3.8-fold increased risk, often appearing as the earliest prodromal symptom over 20 years before diagnosis. Smell identification tests, varying in sensitivity and specificity, support early detection efforts. Screening questions offer a practical first step for community-based PD screening programs.

Method: In the CheckPD digital screening project, 677 participants aged over 40 were enrolled. Of these, 159 identified as high-risk via the application were further assessed using the RBD-HK questionnaire, MoCA test, MDS-UPDRS III, and SS-16. They were divided into high-risk/new diagnosis of early PD (n=107) and healthy (n=52) groups based on criteria including positive RBD-HK results, or 2 of self-reported symptoms (e.g., acting out dreams, constipation, hyposmia, depression), or 1 self-reported symptoms plus with either mild parkinsonian signs, or a first-degree PD family history. McNemar’s Test evaluated discrepancies between self-reported hyposmia and objective SS-16 assessments.

Results: Demographic data and assessment scores are presented in Table 1 [table 1]. SS-16 scores differed significantly between high-risk participants (9.7 ± 3.0) and healthy controls (11.4 ± 1.2, p < 0.001). Among 159 participants, those with normal SS-16 smell reported “No” (84) or “Yes” (19) to the screening question, while hyposmic participants reported “No” (41) or “Yes” (15), showing a significant discrepancy (p = 0.007). In the high-risk and early PD group, normal smell responses were “No” (50) or “Yes” (14), and hyposmic responses were “No” (31) or “Yes” (12; p = 0.017). Healthy controls reported “No” (34) or “Yes” (5) for normal smell and “No” (10) or “Yes” (3) for hyposmia (p = 0.302) [table 2], [figure 2].

Conclusion: Our study shows that while the screening question identifies some individuals with smell loss, it frequently underdetects hyposmia, particularly in populations at risk or in early stages of PD.This discrepancy highlights the limitations of subjective screening tools and objective olfactory testing remains essential for accurate identification of hyposmia.

Figure 1

Table 1

Table 2

References: Bhidayasiri R,et al. The rise of Parkinson’s disease is a global challenge, but efforts to tackle this must begin at a national level: a protocol for national digital screening and “eat, move, sleep” lifestyle interventions to prevent or slow the rise of non-communicable diseases in Thailand. Front Neurol. 2024 May 13;15:1386608. doi: 10.3389/fneur.2024.1386608. PMID: 38803644; PMCID: PMC11129688.

Schaeffer E, Postuma RB, Berg D. Prodromal PD: A new nosological entity. Prog Brain Res. 2020;252:331-356. doi: 10.1016/bs.pbr.2020.01.003. Epub 2020 Feb 10. PMID: 32247370.
Sui X, Zhou C, Li J, Chen L, Yang X, Li F. Hyposmia as a Predictive Marker of Parkinson’s Disease: A Systematic Review and Meta-Analysis. Biomed Res Int. 2019 May 19;2019:3753786. doi: 10.1155/2019/3753786. PMID: 31236405; PMCID: PMC6545790.

Fujio H, Inokuchi G, Tatehara S, Kuroki S, Fukuda Y, Kowa H, Nibu KI. Characteristics of Smell Identification Test in Patients With Parkinson Disease. Clin Exp Otorhinolaryngol. 2019 May;12(2):206-211. doi: 10.21053/ceo.2018.01116. Epub 2018 Dec 27. PMID: 30586953; PMCID: PMC6453781.

Trentin S, Fraiman de Oliveira BS, Ferreira Felloni Borges Y, de Mello Rieder CR. Systematic review and meta-analysis of Sniffin Sticks Test performance in Parkinson’s disease patients in different countries. Eur Arch Otorhinolaryngol. 2022 Mar;279(3):1123-1145. doi: 10.1007/s00405-021-06970-8. Epub 2021 Jul 28. PMID: 34319482.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-discrepancy-between-self-reported-hyposmia-and-objective-assessment-by-sniffin-sticks-in-high-risk-of-synucleinopathies-and-healthy-controls/