Task switching reveals abnormal brain-heart electrophysiological signatures in cognitively healthy individuals with abnormal CSF amyloid/tau, a pilot study
Electroencephalographic (EEG) alpha oscillations have been related to heart rate variability (HRV) and both change in Alzheimer's disease (AD). We explored if task switching reveals altered alpha power and HRV in cognitively healthy individuals with AD pathology in cerebrospinal fluid (CSF) and whether HRV improves the AD pathology classification by alpha power alone. We compared low and high alpha event-related desynchronization (ERD) and HRV parameters during task switch testing between two groups of cognitively healthy participants classified by CSF amyloid/tau ratio: normal (CH-NAT, n = 19) or pathological (CH-PAT, n = 27). For the task switching paradigm, participants were required to name the color or word for each colored word stimulus, with two sequential stimuli per trial. Trials include color (cC) or word (wW) repeats with low load repeating, and word (cW) or color switch (wC) for high load switching. HRV was assessed for RR interval, standard deviation of RR-intervals (SDNN) and root mean squared successive differences (RMSSD) in time domain, and low frequency (LF), high frequency (HF), and LF/HF ratio in frequency domain. Results showed that CH-PATs compared to CH-NATs presented: 1) increased (less negative) low alpha ERD during low load repeat trials and lower word switch cost (low alpha: p = 0.008, Cohen's d = −0.83, 95% confidence interval −1.44 to −0.22, and high alpha: p = 0.019, Cohen's d = −0.73, 95% confidence interval −1.34 to −0.13); 2) decreasing HRV from rest to task, suggesting hyper-activated sympatho-vagal responses. 3) CH-PATs classification by alpha ERD was improved by supplementing HRV signatures, supporting a potentially compromised brain-heart interoceptive regulation in CH-PATs. Further experiments are needed to validate these findings for clinical significance.
© 2021 The Authors. Published by Elsevier B.V. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Received 29 April 2021, Revised 3 October 2021, Accepted 12 October 2021, Available online 17 October 2021. Betty Chung and David Buennagel assisted with participant recruitment. We thank the study participants for their altruistic participation in this research. We thank Dr. Janice Pogoda for statistical help. Cathleen Molloy helped with edits. Some data relied upon in this study was derived from research performed at HMRI by Dr. Michael G. Harrington. This work was supported by National Institute on Aging [grant number R56AG063857, R01AG063857] and L. K. Whittier Foundation. CRediT authorship contribution statement: Conceived and designed the experiments: XA, MGH. Performed the experiments: XA MGH. Analyzed the data: RJA AL RR AF MK MGH XA. Wrote the paper: RJA AL RR XA. Edited the paper: RJA AL RR RK DW SH SS AF MK MGH XA. All authors contributed towards the final manuscript.
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