[Olfactory dysfunction in Parkinson disease and REM sleep behavior disorder]

Area of Science:

• Neurology
• Neuroscience
• Biomarker Research

Context:

• Olfactory dysfunction affects over 90% of Parkinson disease (PD) patients, often appearing in early stages.
• Smell testing offers a simpler, more accessible biomarker compared to neuroimaging.
• REM sleep behavior disorder (RBD) is linked to synucleinopathies, including PD, DLB, and MSA.

Purpose:

• To evaluate olfactory dysfunction as an early diagnostic biomarker for Parkinson disease (PD).
• To assess the utility of smell identification tests in differentiating PD from other parkinsonian syndromes.
• To explore the connection between olfactory dysfunction and synucleinopathies like DLB and RBD.

Summary:

• Hyposmia (reduced sense of smell) is a prevalent early symptom in PD.
• Smell identification tests like Sniffin' Sticks and UPSIT can aid in PD diagnosis and differential diagnosis.
• Reduced odor identification is observed in PD, DLB, and RBD, distinguishing them from healthy individuals.

Impact:

• Early diagnosis of PD may be improved through olfactory testing.
• Understanding olfactory dysfunction pathophysiology could illuminate mechanisms of Lewy body diseases.
• This research highlights smell tests as valuable tools in neurodegenerative disease research and clinical practice.