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P1–216: Obstructive sleep apnea and daytime resting EEG in mild Alzheimer's disease
Author(s) -
Johnsen Kristinn,
Helgadóttir Halla,
Emilsdóttir Ásdís,
Hannesdottir Kristin,
Davidsdottir Solveig,
Valgardsdottir Arndis,
Arnardottir Erna,
Arvidsson Annie,
Gislasson Thorarinn,
Snædal Jón
Publication year - 2013
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2013.05.440
Subject(s) - medicine , dementia , electroencephalography , obstructive sleep apnea , polysomnography , cardiology , sleep apnea , apnea , disease , anesthesia , psychiatry
Background:AD is associated with memory impairments and neurodegeneration in the hippocampus. Others showed that normal elders with early AD evidenced by increased brain amyloid b (Ab), had impaired functional connectivity with posterior cingulated cortex or precuneus [J Neurosci. 2009 (40):12686-94; Biol Psychiatry. 2010 67(6):584-7]. Our goal was to test the hypothesis that early AD, evidenced by increased brain amyloid b (Ab), is associated with reduction of hippocampal volume and alternation of functional connectivity of the hippocampus-centeredmemory network, in the absence of neuropsychological change.Methods: Cognitive normal elderly (N1⁄424, aged 60 89 years) had brain Ab assessedwith florbetapir F 18 PET by visual ratings and standard uptake value ratio (SUVr). Nine participants were A b + and 15 were negative A b -. Whole brain resting-state fMRI was acquired and registered to a template T1 image. Correlation coefficient with a seed region in combined bilateral hippocampal head was calculated with every voxel in the forebrain gray matter. Hippocampal and cortical volumes were measured with Freesurfer and hippocampal subfield volumes in the body were measured with ASHS.Results: There were no effects of Ab on standard neuropsychological tests, a memory-related pattern separation test, or cortical gray matter volumes. In comparison with A b subjects, A b + subjects had reduced volumes in right CA3 of the hippocampal body (256 5 vs. 316 7 mm 3), left hippocampal head (14956 190 vs. 1757 6 209 mm 3), and entire hippocampus (7312 6 631 vs. 7912 6 705 mm 3). In comparison with the A b group, functional connectivity with the hippocampus seed in the A b + group increased in left thalamus but decreased in left middle frontal gyrus and left precentral gyrus (p<0.01 after correction, Figure 1). The connectivity between the hippocampus seed and the left thalamus cluster significantly correlated with SUVr even when covarying for either age or hippocampal volume (r1⁄40.50, p<0.05) and marginally significant for the other two clusters. Conclusions: Our finding of changes in structure and functional connectivity of the hippocampus in early AD demonstrates disruption of the hippocampus-centered memory network prior to neuropsychological changes. These neuroimaging findings may be used for early detection and to identify subjects for AD prevention trials.