Objective:

To determine the association between hyposmia and frontal lobe dysfunction (FLD) in patients with Parkinson’s disease (PD)

Background:

Pathological changes in frontal and temporal structures involving the olfactory process were confirmed in PD patients with hyposmia. FLD was associated with a deficit in odor identification among other neurological diseases such as frontotemporal dementia, amyotrophic lateral sclerosis, and cortico-basal syndrome. However, this relationship among PD patients remains unreported.

Design/Methods:

We retrospectively screened consecutive hospitalized patients with PD. We defined FLD as lower than 14 on the Frontal Assessment Battery. T & T olfactometer was used to evaluate for hyposmia, consisting of five different odors: floral smell like rose, sweet burning smell like pudding, sweaty smell like stuffy socks, fruity smell like canned peaches, and musty smell like feces. In this test, the odor-identification threshold is the primary indicator and severe hyposmia was defined as higher than four on a five-point scale. First, we aimed to reveal whether severe hyposmia could be associated with FLD. Second, we evaluated which specific odor items could be related to FLD.

Results:

We included 235 PD patients (125 [53 %] male, median age 69 years, and median Hoehn Yahr stage 2), and FLD was observed in 84 (36 %) patients. In multivariable logistic regression analysis, severe hyposmia (OR 2.860, 95% CI 1.103 – 7.417, p = 0.031) and lower MoCA-J (OR 0.666, 95% CI 0.578 – 0.766, p < 0.001) were associated with FLD. From the perspective of the odor item, severe hyposmia for fruity smell like canned peaches was associated with FLD (OR 3.752, 95% CI 1.370 – 10.276, p = 0.010).

Conclusions: