Objective: To evaluate whether questionnaire-based variables can identify individuals with Olfactory Dysfunction (OD), thereby supporting a targeted preselection approach for Parkinson’s Disease (PD) screening.

Background: OD is an established feature of PD and often precedes clinical diagnosis, making it valuable for risk identification. The University of Pennsylvania Smell Identification Test (UPSIT) allows large-scale remote screenings. However, implementing olfactory testing in an unselected population may be limited by logistical and cost restraints. Targeted preselection therefore may enhance screening efficacy.

Method: This study was conducted within the European multicenter Healthy Brain Aging (HeBA) initiative. Individuals aged >50 years without a prior diagnosis of PD completed an online questionnaire on demographics, medical history, PD-risk factors and prodromal symptoms. Further, participants performed an UPSIT and were subsequently stratified by age (5-year intervals) and sex. Within each stratum, the lowest 10% of UPSIT scores were classified as hyposmic. Associations between clinical and demographic factors and OD were analyzed using univariate and multivariate logistic regression models, reported as odds ratios (ORs) with 95% confidence intervals (CIs).

Results: A total of 8,438 participants (mean age 62.9±7.8 years, 61.1% female) provided UPSIT results, of whom 9.8% were classified as hyposmic. In univariate logistic regression analyses, self-reported hyposmia showed the strongest association with OD (OR = 6.56, 95% CI 5.21–7.53). Essential tremor (OR = 1.74, 95% CI 1.11–2.66) and lower educational level (≤ high school or similar; OR = 1.20, 95% CI 1.07–1.31) were associated with OD, while prodromal markers (e.g. dream enactment behavior [DEB]) were not. In multivariate models, subjective hyposmia remained the strongest predictor of OD (OR = 6.65, 95% CI 5.69–7.77), while from additional prodromal features and risk markers only DEB contributed modestly to the overall model.

Conclusion: Self-reported hyposmia emerged as the strongest predictor of OD, indicating its potential utility as a practical instrument for population-based pre-screening. In contrast, information on DEB and other risk and prodromal markers showed lower to no contribution to the identification of olfactory impairment.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/optimizing-identification-of-hyposmia-for-parkinsons-disease-risk-screening-results-from-the-healthy-brain-aging-study/