EEG-based vigilance and cerebral glucose metabolism – a parallel EEG and FDG PET study

Introduction: Patients with Alzheimer's disease (AD) compared to controls can be characterized by a pattern of reduced glucose metabolism in temporoparietal, posterior cingulate, and frontal cortices using 2-[18F]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET). Sleep studies demonstrated an altered glucose metabolism in some of the respective cortices during the transition from wake to sleep. While sleep can be excluded during the examination, drowsiness may still bias the glucose metabolism of these patients during the FDG PET. Methods: In the present study, a sample of 10 patients with probable AD (53–76 years, 3 women) was investigated with simultaneous EEG PET (FDG). According to the drowsiness level the sample was median split into a group with stable and unstable EEG-vigilance, respectively. Imaging analyses were performed in SPM5. Results: Patients with stable compared to unstable EEG-vigilance showed an increased glucose metabolism in the lateral superior temporal gyrus (p=.001 uncorrected, k=30). Patients with unstable compared to stable EEG-vigilance showed an increased glucose metabolism in the lateral and medial frontal gyrus, and the median cingulate gyrus (p=.001 uncorrected, k=30). Conclusion: These preliminary results demonstrate the potential of EEG-vigilance to modulate the cerebral glucose metabolism in AD during FDG PET.