Pauline Brayet: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montreal, Montreal, Quebec, Canada Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada.
Dominique Petit: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montreal, Montreal, Quebec, Canada Department of Psychiatry, Université de Montréal, Montreal, Quebec, Canada.
Birgit Frauscher: Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
Jean-François Gagnon: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montreal, Montreal, Quebec, Canada Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada.
Nadia Gosselin: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montreal, Montreal, Quebec, Canada Department of Psychology, Université de Montréal, Montreal, Quebec, Canada.
Katia Gagnon: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montreal, Montreal, Quebec, Canada Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada.
Isabelle Rouleau: Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada Neurology Service, Hôpital Notre-Dame du CHUM, Montreal, Quebec, Canada.
Jacques Montplaisir: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montreal, Montreal, Quebec, Canada Department of Psychiatry, Université de Montréal, Montreal, Quebec, Canada jy.montplaisir@umontreal.ca.
The basal forebrain cholinergic system, which is impaired in early Alzheimer's disease, is more crucial for the activation of rapid-eye-movement (REM) sleep electroencephalogram (EEG) than it is for wakefulness. Quantitative EEG from REM sleep might thus provide an earlier and more accurate marker of the development of Alzheimer's disease in subjects with mild cognitive impairment (MCI) subjects than that from wakefulness. To assess the superiority of the REM sleep EEG as a screening tool for preclinical Alzheimer's disease, 22 subjects with amnestic MCI (a-MCI; 63.9±7.7 years), 10 subjects with nonamnestic MCI (na-MCI; 64.1±4.5 years) and 32 controls (63.7±6.6 years) participated in the study. Spectral analyses of the waking EEG and REM sleep EEG were performed and the [(delta+theta)/(alpha+beta)] ratio was used to assess between-group differences in EEG slowing. The a-MCI subgroup showed EEG slowing in frontal lateral regions compared to both na-MCI and control groups. This EEG slowing was present in wakefulness (compared to controls) but was much more prominent in REM sleep. Moreover, the comparison between amnestic and nonamnestic subjects was found significant only for the REM sleep EEG. There was no difference in EEG power ratio between na-MCI and controls for any of the 7 cortical regions studied. These findings demonstrate the superiority of the REM sleep EEG in the discrimination between a-MCI and both na-MCI and control subjects.
