Olfactory function combined with morphology distinguishes Parkinson's disease

Area of Science:

• Neurology
• Radiology
• Neuroimaging

Background:

• Parkinson's disease (PD) and related disorders share overlapping symptoms, complicating differential diagnosis.
• Olfactory dysfunction and cardiovascular autonomic neuropathy are common in PD.

Purpose of the Study:

• To assess the utility of olfactory bulb and tract (OB & T) volume on MRI for differentiating PD from PD-related disorders.
• To correlate OB & T volume with olfactory function and cardiovascular dysautonomia.

Main Methods:

• Compared MRI-derived OB & T volumes in patients with PD, multiple system atrophy (MSA), and progressive supranuclear palsy/corticobasal degeneration (PSP/CBD).
• Utilized odor stick identification test for Japanese (OSIT-J) and (123)I-meta-iodobenzylguanidine (MIBG) scintigraphy.
• Defined cut-off values for OSIT-J, MIBG uptake, and OB & T volume to discriminate PD.

Main Results:

• OB & T volume was significantly smaller in PD patients compared to MSA and PSP/CBD groups (p < 0.05).
• A combination of OSIT-J score <8, heart/mediastinum ratio <1.6, and OB & T volume <270 mm(3) identified PD with 91% accuracy.
• Decreasing OSIT-J scores and OB & T volumes correlated with an increased likelihood of PD (p < 0.001).

Conclusions:

• Combined morphological (OB & T volume) and functional (olfactory, cardiovascular) assessments show promise for differentiating PD.
• These preliminary findings suggest MRI-based OB & T volume is a valuable biomarker in PD diagnosis.