Association of plasma amyloid-ß oligomerization with theta/beta ratio in older adults.

ABSTRACT

Background: Oligomeric Aß (OAß) is a promising candidate marker for Alzheimer's disease (AD) diagnosis. Electroencephalography (EEG) is a potential tool for early detection of AD. Still, whether EEG power ratios, particularly the theta/alpha ratio (TAR) and theta/beta ratio (TBR), reflect Aß burden-a primary mechanism underlying cognitive impairment and AD. This study investigated the association of TAR and TBR with amyloid burden in older adults based on MDS-OAß levels. Methods: 529 individuals (aged ≥60 years) were recruited. All participants underwent EEG (MINDD SCAN, Ybrain Inc., South Korea) and AlzOn™ test (PeopleBio Inc., Gyeonggi-do, Republic of Korea) for quantifying MDS-OAß values in the plasma. EEG variables were log-transformed to normalize the data distribution. Using the MDS-OAß cutoff value (0.78 ng/mL), all participants were classified into two groups high MDS-OAß and low MDS-OAß. Results: Participants with high MDS-OAß levels had significantly higher TARs and TBRs than those with low MDS-OAß levels. The log-transformed TBRs in the central lobe (ß = 0.161, p = 0.0026), frontal lobe (ß = 0.145, p = 0.0044), parietal lobe (ß = 0.166, p = 0.0028), occipital lobe (ß = 0.158, p = 0.0058), and temporal lobe (beta = 0.162, p = 0.0042) were significantly and positively associated with increases in MDS-OAß levels. After adjusting for the Bonferroni correction, the TBRs in all lobe regions, except the occipital lobe, were significantly associated with increased MDS-OAß levels. Conclusion: We found a significant association of MDS-OAß with TBR in older adults. This finding indicates that an increase in amyloid burden may be associated with an increase in the low-frequency band and a decrease in the relatively high-frequency band.