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Relationship between regional white matter hyperintensities and alpha oscillations in older adults
(2021)
Aging is associated with increased white matter hyperintensities (WMHs) and with alterations of alpha oscillations (7–13 Hz). However, a crucial question remains, whether changes in alpha oscillations relate to aging per se or whether this relationship is mediated by age-related neuropathology like WMHs. Using a large cohort of cognitively healthy older adults (N = 907, 60–80 years), we assessed relative alpha power, alpha peak frequency, and long-range temporal correlations from resting-state EEG. We further associated these parameters with voxel-wise WMHs from 3T MRI. We found that a higher prevalence of WMHs in the superior and posterior corona radiata as well as in the thalamic radiation was related to elevated alpha power, with the strongest association in the bilateral occipital cortex. In contrast, we observed no significant relation of the WMHs probability with alpha peak frequency and long-range temporal correlations. Finally, higher age was associated with elevated alpha power via total WMH volume. We suggest that an elevated alpha power is a consequence of WMHs affecting a spatial organization of alpha sources.
Relationship between regional white matter hyperintensities and alpha oscillations in older adults
(2020)
White matter hyperintensities (WMHs) in the cerebral white matter and attenuation of alpha oscillations (AO; 7–13 Hz) occur with the advancing age. However, a crucial question remains, whether changes in AO relate to aging per se or they rather reflect the impact of age-related neuropathology like WMHs. In this study, using a large cohort (N=907) of elderly participants (60-80 years), we assessed relative alpha power (AP), individual alpha peak frequency (IAPF) and long-range temporal correlations (LRTC) from resting-state EEG. We further associated these parameters with voxel-wise WMHs from 3T MRI. We found that higher prevalence of WMHs in the superior and posterior corona radiata was related to elevated relative AP, with strongest correlations in the bilateral occipital cortex, even after controlling for potential confounding factors. In contrast, we observed no significant relation of probability of WMH occurrence with IAPF and LRTC. We argue that the WMH-associated increase of AP reflects generalized and likely compensatory changes of AO leading to a larger number of synchronously recruited neurons.
Relationship between regional white matter hyperintensities and alpha oscillations in older adults
(2020)
Objective: To investigate whether regional white matter hyperintensities (WMHs) relate to alpha oscillations (AO) in a large population-based sample of elderly individuals.
Methods: We associated voxel-wise WMHs from high-resolution 3-Tesla MRI with neuronal alpha oscillations (AO) from resting-state multichannel EEG at sensor (N=907) and source space (N=855) in older participants of the LIFE-Adult study (60–80 years). In EEG, we computed relative alpha power (AP), individual alpha peak frequency (IAPF), as well as long-range temporal correlations (LRTC) that represent dynamic properties of the signal. We implemented whole-brain voxel-wise regression models to identify regions where parameters of AO were linked to probability of WMH occurrence. We further used mediation analyses to examine whether WMH volume mediated the relationship between age and AO.
Results: Higher prevalence of WMHs in the superior and posterior corona radiata was related to elevated relative AP, with strongest correlations in the bilateral occipital cortex, even after controlling for potential confounding factors. The age-related increase of relative AP in the right temporal brain region was shown to be mediated by total WMH volume.
Conclusion: A high relative AP corresponding to increased regional WMHs was not associated with age per se, in fact, this relationship was mediated by WMHs. We argue that the WMH-associated increase of AP reflects a generalized and likely compensatory spread of AO leading to a larger number of synchronously recruited neurons. Our findings thus suggest that longitudinal EEG recordings might be sensitive to detect functional changes due to WMHs.
Relationship between regional white matter hyperintensities and alpha oscillations in older adults
(2021)
Aging is associated with increased white matter hyperintensities (WMHs) and with the alterations of alpha oscillations (7–13 Hz). However, a crucial question remains, whether changes in alpha oscillations relate to aging per se or whether this relationship is mediated by age-related neuropathology like WMHs. Using a large cohort of cognitively healthy older adults (N=907, 60-80 years), we assessed relative alpha power, alpha peak frequency, and long-range temporal correlations (LRTC) from resting-state EEG. We further associated these parameters with voxel-wise WMHs from 3T MRI. We found that a higher prevalence of WMHs in the superior and posterior corona radiata as well as in the thalamic radiation was related to elevated alpha power, with the strongest association in the bilateral occipital cortex. In contrast, we observed no significant relation of the WMHs probability with alpha peak frequency and LRTC. Finally, higher age was associated with elevated alpha power via total WMH volume. Although an increase in alpha oscillations due to WMH can have a compensatory nature, we rather suggest that an elevated alpha power is a consequence of WMH affecting a spatial organization of alpha sources.
Highlights
• A big dataset reveals age-related alterations in EEG biomarkers and cognition.
• Prominent decline of individual alpha peak frequency primarily in temporal lobes.
• A positive association between individual alpha peak frequency and working memory.
• Absence of age-related alpha power decline when controlling for 1/f decay of the PSD.
• Alpha power is negatively associated with the speed of processing in elderly sample.
Abstract
While many structural and biochemical changes in the brain have previously been associated with older age, findings concerning functional properties of neuronal networks, as reflected in their electrophysiological signatures, remain rather controversial. These discrepancies might arise due to several reasons, including diverse factors determining general spectral slowing in the alpha frequency range as well as amplitude mixing between the rhythmic and non-rhythmic parameters. We used a large dataset (N = 1703, mean age 70) to comprehensively investigate age-related alterations in multiple EEG biomarkers taking into account rhythmic and non-rhythmic activity and their individual contributions to cognitive performance. While we found strong evidence for an individual alpha peak frequency (IAF) decline in older age, we did not observe a significant relationship between theta power and age while controlling for IAF. Not only did IAF decline with age, but it was also positively associated with interference resolution in a working memory task primarily in the right and left temporal lobes suggesting its functional role in information sampling. Critically, we did not detect a significant relationship between alpha power and age when controlling for the 1/f spectral slope, while the latter one showed age-related alterations. These findings thus suggest that the entanglement of IAF slowing and power in the theta frequency range, as well as 1/f slope and alpha power measures, might explain inconsistencies reported previously in the literature. Finally, despite the absence of age-related alterations, alpha power was negatively associated with the speed of processing in the right frontal lobe while 1/f slope showed no consistent relationship to cognitive performance. Our results thus demonstrate that multiple electrophysiological features, as well as their interplay, should be considered for the comprehensive assessment of association between age, neuronal activity, and cognitive performance.