The Study Of Quantitative EEG In Patients With Subjective Cognitive Decline

Purpose and Background:We explored the power spectrum characteristics of quantitative EEG in subjective cognitive decline(SCD)patients to find quantitative EEG indicators that may have diagnostic value for SCD,and thus provide a basis for early diagnosis of cognitive decline.Method:The study was carried out from January 2017 to January 2019 in the Department of Neurology,Inpatient Department and Outpatient Department of our hospital.Thirty patients with subjective cognitive decline and thirty patients with mild cognitive impairment(MCI)were selected as subjects.Twenty-nine healthy elderly volunteers with negative diagnosis of cognitive decline,depression and other mental illnesses as well as various chronic diseases,were enrolled as controls.MMSE test and EEG monitoring for longer than 2 hours were performed on all subjects,and the20-minute undisturbed EEG recordings obtained during the conscious state with closed eyes state were used to analyze the power spectrum of the brain topographic map.The power spectra of δ-,θ-,α-and β-waves of each group were quantitatively analyzed and compared with each other.α/θ and(δ+θ)/(α+β)power spectral ratios,and correlation between them and MMSE score were also analyzed.Result:(1)No statistically significant difference was found between the results ofα-wave EEG power spectrum analysis of SCD group and normal group(P>0.05),whereas α-wave EEG power spectrum of MCI group was lower than SCD and normal group(P<0.01).β-waves of SCD group were lower than normal group(p<0.01),andβ-waves of MCI group were lower than SCD and normal group(p<0.05).θ-waves of SCD group were higher than normal group,while θ-waves of MCI group were higher of both SCD and normal group(p<0.05).No statistically significant differences were found between δ-waves of SCD,MCI and normal group(p>0.05),albeit δ-waves of MCI group were higher than those of normal group(p<0.05).The results of relativepower value α/θ of SCD group was lower than normal group,whereas the relative power value α/θ of MCI group was lower than SCD and normal group(p<0.05).The values of relative power value(δ+θ)/(α+β)of SCD group was higher than normal group,and MCI group had higher values than SCD and normal group(p<0.01).(2)The correlation between α/θ,(δ+θ)/(α+β)power spectral ratios and MMSE score was 0.53 and-0.47,respectively,indicating medium correlation.Conclusion:(1)Power spectrum characteristics of quantitative EEG from SCD patients exhibit lower values for α-,β-waves and α/θ ratio,whereas the values of θ-waves and(δ+θ)/(α+β)ratio are increased.These indicators may be useful for distinguishing between healthy elderly,and those who suffer from SCD or MCI,and could thus be used for diagnosis of SCD.(2)The α/θ ratio has positive correlation with MMSE score,whereas the(δ+θ)/(α+β)ratio has negative correlation with MMSE score.In other words,while MMSE score decreases,the value of α/θ ratio also decreases,and the value of(δ+θ)/(α+β)increases.