Objective: We examined the relation between Apolipoprotein E epsilon4 allele (ApoE epsilon4) genotype and functional connectivity measured by Electroencephalography (EEG) in patients with Alzheimer's disease (AD) and patients with subjective complaints (SC).
Methods: We included 43 patients with AD (age (SD)=74.2 (4.0), m/f=22/21; 30 of ApoE epsilon4 carriers) and 21 patients with SC (age (SD)=73.2 (5.2), m/f=13/8; 7 ApoE epsilon4 carriers) for this study. Resting state EEGs were recorded in all subjects. Synchronisation likelihood (SL) between local cortical areas was compared in the alpha and beta band according to ApoE epsilon4 status and diagnosis.
Results: ApoE epsilon4 carriers had higher SL values in lower and upper alpha band, in both diagnostic groups. In upper alpha band and beta band AD patients had lower SL than patients with SC, was irrespective of ApoE status.
Conclusion: The effects of AD and ApoE epsilon4 on functional connectivity are opposite and independent.
Significance: The observed increase in SL in both AD and patients with SC carrying ApoE epsilon4 suggests a strong genetic impact of ApoE epsilon4 on brain function.