Distinct Effects of the Apolipoprotein E ε4 Genotype on Associations Between Delayed Recall Performance and Resting-State Electroencephalography Theta Power in Elderly People Without Dementia

Abstract

BackgroundAbnormal electroencephalography (EEG) activity has been demonstrated in mild cognitive impairment (MCI), and theta rhythm might be inversely related to memory. The apolipoprotein E (ApoE) epsilon 4 (ε4) allele, as a genetic vulnerability factor for pathologic and normal age-related cognitive decline, may influence different patterns of cognitive dysfunction. Therefore, the present study primarily aimed to verify the role of resting theta rhythm in delayed recall deficits, and further explore the effects of the ApoE genotype on the associations between the resting theta power and delayed recall performance in the elderly individuals without dementia.MethodsA total of 47 individuals without dementia, including 23 MCI and 24 healthy subjects (HCs), participated in the study. All subjects were administered the Hopkins Verbal Learning Test–Revised (HVLT-R) to measure delayed recall performance. Power spectra based on resting-state EEG data were used to examine brain oscillations. Linear regression was used to examine the relationships between EEG power and delayed recall performance in each subgroup.ResultsThe increased theta power in the bilateral central and temporal areas (Ps = 0.02–0.044, uncorrected) was found in the patients with MCI, and were negatively correlated with delayed recall performance (rs = −0.358 to −0.306, Ps = 0.014–0.036, FDR corrected) in the elderly individuals without dementia. The worse delayed recall performance was associated with higher theta power in the left central and temporal areas, especially in ApoE ε4 non-carriers and not in carriers (rs = −0.404 to −0.369, Ps = 0.02–0.035, uncorrected).ConclusionOur study suggests that theta disturbances might contribute to delayed recall memory decline. The ApoE genotype may have distinct effects on EEG-based neural correlates of episodic memory performance.

Enriched environment attenuates hippocampal theta and gamma rhythms dysfunction in chronic cerebral hypoperfusion via improving imbalanced neural afferent levels

“…In the hippocampus of CCH rats, our field potential analysis revealed an abnormal power distribution of CA1 ( Figure 3 ). The power of theta and SG rhythms was significantly reduced in CCH rats, which is consistent with findings in other models of cognitive disorders ( Gonzalez et al, 2022 ; Wang et al, 2022 ). EE improved the damaged theta and SG oscillations.…”

“…There is substantial evidence linking theta and gamma rhythms and their interactions in the hippocampus to neurological and psychiatric diseases ( Uhlhaas and Singer, 2010 ; Zheng and Zhang, 2015 ; Zott et al, 2018 ; Yakubov et al, 2022 ). Abnormalities in the theta rhythm contribute to amnesia and mild cognitive impairment ( Gonzalez et al, 2022 ; Wang et al, 2022 ). Gamma rhythm and theta-gamma phase amplitude coupling (PAC) are closely linked to Alzheimer’s disease, attention deficit, and associative memory impairment in old age ( Karlsson et al, 2022 ; Liu et al, 2022 ; Mehak et al, 2022 ).…”