Olfactory swab sampling optimization for α-synuclein aggregate detection in patients with Parkinson's disease

Area of Science:

• Neurology
• Biochemistry
• Medical Diagnostics

Background:

• Parkinson's disease (PD) diagnosis relies on clinical symptoms and biomarkers.
• Real-time quaking-induced conversion (RT-QuIC) detects pathological alpha-synuclein (α-syn) but shows variable accuracy in olfactory mucosa (OM) for PD.
• The distribution of α-syn in OM may influence RT-QuIC detection sensitivity.

Purpose of the Study:

• To investigate if nasal swab (NS) location affects pathological α-syn detection in PD patients using RT-QuIC.
• To compare the diagnostic yield of RT-QuIC from different nasal regions (agger nasi [AN] and middle turbinate [MT]) and cerebrospinal fluid (CSF).

Main Methods:

• Nasal swabs were collected from AN and MT in 66 PD patients and 29 controls.
• Cerebrospinal fluid (CSF) was obtained from 43 patients.
• All samples were analyzed for pathological α-syn using RT-QuIC; immunocytochemistry was also performed.

Main Results:

• RT-QuIC sensitivity for α-syn detection was significantly higher from AN (84%) compared to MT (45%) in PD patients.
• Immunocytochemistry revealed greater olfactory neural cell presence in AN swabs.
• CSF RT-QuIC showed higher accuracy (92%) than NS, but NS is less invasive.

Conclusions:

• Nasal swab collection from the AN region enhances RT-QuIC sensitivity for detecting pathological α-syn in PD.
• RT-QuIC from AN may serve as an ancillary, non-invasive tool for Parkinson's disease diagnosis.
• Understanding α-syn distribution in the olfactory mucosa is crucial for optimizing diagnostic strategies.