Decrease of delta oscillatory responses is associated with increased age in healthy elderly
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Background: The purpose of this study was to investigate changes in delta event-related oscillations (EROs) in younger and older healthy elderly subjects. We hypothesized that delta EROs were affected by age-related changes, which could be reflected in a visual oddball paradigm. Method: The study included two groups of subjects, 17 younger healthy elderly (mean age: 63.1 +/- 2.8 years) and 17 gender- and education-matched older healthy elderly (mean age: 79.6 +/- 5.2 years), who performed a visual oddball paradigm. EEG was recorded from F-3, F-z, F-4, C-3, C-z, C-4, P-3, P-z, P-4, O-1, O-z and O-2 locations. Peak-to-peak amplitudes of delta (0.5-3 Hz) target ERO responses during the post-stimulus 0-800 ms time window were measured. Repeated measures of ANOVA was used to analyze four locations (frontal, central, parietal, occipital), at three sagittal (left, midline, right) sites. Independent t-tests were applied for post-hoc analyses. Results: The older healthy elderly group had 16-25% lower values for the maximum peak-to-peak amplitudes of delta ERO compared with the younger healthy elderly group over frontal (p < 0.003), central (p < 0.0001) and parietal (p < 0.007) locations [F-3.95 = 4396, p = 0.015] Furthermore, there was a moderate negative correlation between age and C-z peak-to-peak amplitude of target delta responses [r = -0.401, p < 0.02], indicating the notion that peak-to-peak amplitude of C-z decreases as age increases. Conclusion: In the present study younger healthy elderly showed significantly higher event-related delta responses than older healthy elderly at frontal, central and parietal locations. Moreover, delta ERO responses decreased in accordance with age. (C) 2015 Elsevier B.V. All rights reserved.