Correlation of CSF Biomarkers with Cognitive Screening Tests and PET Scan: A Tandem Approach

Area of Science:

• Neurology
• Biochemistry
• Medical Diagnostics

Background:

• FDA-approved Roche Elecsys assays measure cerebrospinal fluid (CSF) biomarkers: amyloid beta 42 (Aβ42), total tau (t-Tau), and phosphorylated tau 181 (p-Tau 181) for Alzheimer's disease (AD).
• Cognitive screening functions (SCFs) are commonly used to identify patients with suspected dementia and AD.

Purpose of the Study:

• To evaluate the correlation between CSF pTau181/Aβ42 ratios and screening for cognitive functions (SCFs) with actual AD diagnosis confirmed by PET scans.
• To determine the diagnostic accuracy of CSF biomarkers compared to SCFs in identifying Alzheimer's disease.

Main Methods:

• CSF samples from 143 patients were analyzed for Aβ42, t-Tau, and p-Tau 181 using Roche Elecsys assays.
• Fluorodeoxyglucose PET scans were used for AD diagnosis confirmation.
• Cognitive screening functions (SCFs) included MOCA, SLUMS, STMS, or MMSE.

Main Results:

• A statistically significant association was found between positive CSF biomarker tests (pTau181/Aβ42 ratio >0.023) and PET scan results in 40 patients (p<0.01).
• Screening for cognitive functions (SCFs) showed a poor correlation with PET scan results (p=0.059).
• A combination of abnormal SCF and positive CSF biomarkers significantly predicted positive PET imaging results (p<.001).

Conclusions:

• CSF pTau181/Aβ42 ratios demonstrate a stronger correlation with PET scan findings for AD diagnosis than various SCFs.
• A combined approach using both SCFs and CSF biomarkers enhances the correlation with positive PET imaging, improving diagnostic accuracy for Alzheimer's disease.