Task switching challenge to reveal abnormal brain‐heart signatures in cognitively healthy individuals with abnormal CSF amyloid/tau

Abstract

AbstractBackgroundAlpha oscillations during task switching reveals general attention (low alpha) and higher executive attentional control (high alpha). Alpha oscillations have been related to heart rate variability (HRV), both change in Alzheimer’s disease (AD). We aim to explore if task switching challenge with quantitative electroencephalography (qEEG) can reveal abnormal alpha power and HRV in individuals with high risk of AD, and we predict HRV improves qEEG’s detection of high AD risk.MethodWe compared alpha power during task switching testing between two groups of cognitively healthy participants (52‐91 years) based on different cerebrospinal fluid (CSF) amyloid/tau ratio: normal (CH‐NAT, n=19) or pathological amyloid/tau ratio (CH‐PAT, n=27). Participants were required to name the color or word of a colored word for each stimulus, with two sequential stimuli per trial. Alpha event‐related desynchronization (ERD) was analyzed during low load, repeat trials (color‐color or word‐word) and high load, switch trials (color‐word or word‐color). HRV was assessed from 5‐minute ECG recording during rest or task, including: standard deviation of RR‐intervals (SDNN), root mean squared of successive differences (RMSSD) in the time domain, as well as high (HF) and low frequency (LF) in the frequency domain. We trained a binary classifier to predict the CH‐PATs using a 30 random split of training (80%) and testing (20%) data and two‐layer, fully connected neural network after identifying significant qEEG and HRV features.ResultWe found that low alpha power was less negative in CH‐PATs than CH‐NATs (Central: ‐0.18±0.66 vs. ‐0.72±0.72, p=0.011, Cohen’s d=0.79; Parietal: ‐0.25±0.75 vs. ‐0.83±0.92, p=0.024, Cohen’s d=0.70) (Fig. 1). Furthermore, we observed significant HR and LF changes from resting to task state only in CH‐PATs, but not in CH‐NATs (Fig. 2). After identifying brain features and heart features, we explored the HRV effect on brain features’ test accuracy.ConclusionThese results suggest: 1) low alpha power during task switching challenge differs between CH‐PATs and CH‐NATs; 2) HRV suggests hyperactive autonomic regulations from resting to task in CH‐PATs, but not CH‐NATs. qEEG reveals interaction of brain and heart features in early AD pathology that may help early diagnosis and monitoring of novel therapies.