Objective: To evaluate hyposmia as a predictor of non-motor features in patients with early Parkinson’s disease (PD).

Background: Hyposmia is quite a common finding in PD patients, notably in de novo patients. The fact that many patients with an established clinical diagnosis of PD recall a loss of or reduction of the sense of smell that started years before the onset of motor parkinsonism and the reports of hyposmia in asymptomatic first-degree relatives of patients with familial forms of parkinsonism or with sporadic PD suggest that an olfactory deficit might be a premotor sign in PD.

Methods: The Parkinson’s Progression Markers Initiative (PPMI) is a multi-site, prospective study which aims to identify biomarkers in PD. Assessments include the International Parkinson and Movement Disorders Society Unified Parkinson’s disease Rating Scale (MDS-UPDRS) Part I items on cognitive impairment, hyposmia, pain, autonomic nerve system disorders, sleep disorders and neuropsuchiatric disturbances. All participants completed Smell Diskettes Identification test (SDIT) a measure of olfaction. Binary logistic regression was used to examine the relationship between hyposmia and presence of nonmotor features (MDS-UPDRS Part 1 items), controlling for baseline age, disease duration, gender, and years of education.

Results: Individuals were categorized into 3 groups based on baseline SDIT score quartiles (range: 1-8). Compared to normosmics, those in the lowest quartile had 4 times the odds of reporting cognitive difficulties (OR=4.15, 95%CI: 1.96-8.78, p<.05) and twice the odds of reporting anxiety (OR=2.24, 95%CI: 1.21-4.15, p<.05).

Conclusions: Olfactory tests could be useful in the early diagnosis of PD and detected hyposmia is a significant predictor of self-reported cognitive difficulties and anxiety. Idiopathic hyposmia in elderly individuals constitutes a risk of developing PD and promote further study of the impact of hyposmia in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/hyposmia-as-a-predictor-of-non-motor-symptom-in-patients-with-de-novo-parkinsons-disease/