QEEG: The tentative biomarker for early screening of preclinical Alzheimer’s disease or progressiveness of subjective cognitive decline

Abstract

AbstractBackgroundEarly screening biomarker has been required to discriminate higher risk of progressive subgroup in subjective cognitive decline(SCD) at preclinical stage. Study purpose was to identify quantitative EEG patterns among different condition of amnestic SCDMethodFrom 6 dementia clinics in Korea, we enrolled participants aged over 60 years with complaining of persistent cognitive decline, performance range of 7% to 50% of the verbal memory tests and over 7% of the rest subtests of comprehensive neuropsychological battery. Both 18F‐Florbetaben brain amyloid‐beta PET and genetic test for APOE ε4 allele were conducted. EEG was measured at 19 channels of international 10‐20 system under resting state, and spectrum power and power ratio were calculated. Source cortical activity was mathematically estimated by standardized low resolution brain electromagnetic tomography(sLORETA)Result120 SCD subjects (male 53, female 67) were included. Amyloid PET(+) was 25 (20.8%) and APOE ε4 allele (+) was 26(21.6%) independently. Amyloid PET (+) SCD had higher frequency of APOE e4 (48%) compared to amyloid PET (‐) SCD (14%). We selected 67 amyloid PET (‐) SCD older than 65 years to escape age differences between 2 groups. Amyloid PET (+) SCD showed significant increase of relative theta power at left frontotemporal(Fp1, F7, T5), both occipital(O1,2) and right parietal(P4) channels. Similarly, significant enhancement of theta was observed at left superior and transverse temporal, fusiform and cuneus at sLORETA in amyloid PET (+) SCD. Among amyloid PET (+) SCD, APOE ε4 (+) subgroup showed significant increase of theta/beta ratio at both superior frontal and anterior cingulate, right parietal and occipital areaConclusionAmnestic SCD with amyloid (+) showed relative enhancement of slow wave in resting EEG, which have been similarly reported about amnestic MCI or AD dementia. QEEG could be tentative biomarker to screen AD or to predict progressiveness of SCD at preclinical stage. Longitudinal study and development of single quantitative index of QEEG to evaluate individual subject will be needed to confirm its clinical significance.