EEG-based neurophysiological indicators of hallucinations in Alzheimer's disease: Comparison with dementia with Lewy bodies

We studied neurophysiological indicators of hallucinations in Alzheimer's disease patients with hallucinations (ADhall+), and compared them with nonhallucinating AD (ADhall-) and dementia with Lewy bodies (DLBhall+) patients. Thirty-six matched ADhall+and 108 ADhall- and 29 DLBhall+ patients were selected from the Amsterdam Dementia Cohort. Electroencephalography (EEG) spectral and functional connectivity (FC) analyses (phase lag index) were performed. Quantitative and visual EEG measures were combined in a random forest algorithm to determine which EEG-based variable(s) play a role in hallucinations. ADhall+ patients showed lower peak frequency (7.26 vs. 7.94 Hz, p < 0.01), alpha 2-and beta-power, and alpha 2-FC but higher dpowercompared to ADhall-. ADhall+ showed lower delta-power, higher beta-power, and alpha 1-FC than DLBhallthornbut did not differ in peak frequency (7.26 vs. 6.95 Hz), theta -or alpha-power. ADhall+ patients could be differentiated from ADhall- and DLBhall+ with aweighted accuracy of 71% with alpha 1-power and 100% with beta-FC, the 2 most differentiating features. In sum, EEG slowing and decrease in alpha 1-and beta-band activity form potential neurophysiological indicators of underlying cholinergic deficiency in ADhall+ and DLBhall+. (C) 2018 Elsevier Inc. All rights reserved.