Abnormalities of functional cortical source connectivity of resting-state electroencephalographic alpha rhythms are similar in patients with mild cognitive impairment due to Alzheimer's and Lewy body diseases.

Previous evidence has shown different resting-state eyes-closed electroencephalographic delta (<4 Hz) and alpha (8–10.5 Hz) source connectivity in subjects with dementia due to Alzheimer's (ADD) and Lewy body (DLB) diseases. The present study tested if the same differences may be observed in the prodromal stages of mild cognitive impairment (MCI). Here, clinical and resting-state eyes-closed electroencephalographic data in age-, gender-, and education-matched 30 ADMCI, 23 DLBMCI, and 30 healthy elderly (Nold) subjects were available in our international archive. Mini-Mental State Evaluation (MMSE) score was matched in the ADMCI and DLBMCI groups. The eLORETA freeware estimated delta and alpha source connectivity by the tool called lagged linear connectivity (LLC). Area under receiver operating characteristic curve (AUROCC) indexed the classification accuracy among individuals. Results showed that widespread interhemispheric and intrahemispheric LLC solutions in alpha sources were abnormally lower in both MCI groups compared with the Nold group, but with no differences were found between the 2 MCI groups. AUROCCs of LLC solutions in alpha sources exhibited significant accuracies (0.72–0.75) in the discrimination of Nold versus ADMCI-DLBMCI individuals, but not between the 2 MCI groups. These findings disclose similar abnormalities in ADMCI and DLBMCI patients as revealed by alpha source connectivity. It can be speculated that source connectivity mostly reflects common cholinergic impairment in prodromal state of both AD and DLB, before a substantial dopaminergic derangement in the dementia stage of DLB. • We evaluated the abnormalities in functional cortical connectivity computed in rsEEG sources in subjects with Mild Cognitive Impairment due to Alzheimer's and Lewy Body disease. • At the group level, EEG markers of functional cortical connectivity were abnormally lower in in Alzheimer's Disease (ADD) and Lewy Body Disease (DLB) patients compared to healthy elderly subjects (Nold). • At the group level, EEG markers of functional cortical connectivity were similar between in ADD and DLB patients compared to Nold subjects. • At the individual level, EEG marker of functional cortical connectivity exhibited better classification accuracies for the discrimination of ADD versus Nold, and DLB versus Nold, but not between ADD and DLB. [ABSTRACT FROM AUTHOR]