Amplitude coupling is altered in delirium of various etiologies: Results from a retrospective multi-center case-control EEG study.

OBJECTIVE

Delirium manifests with comparable clinical presentations, regardless of its heterogeneous etiology. This suggests a final common pathway such as decreased electroencephalography (EEG) phase coupling. This study investigates if amplitude coupling, another mode of neural communication, is altered in delirium due to different etiologies.

METHODS

We analyzed EEGs of patients from three sites with either postoperative, poststroke or medical delirium and non-delirious control patients. Amplitude envelope correlation corrected for spatial leakage (AECc) was calculated and Mann-Whitney U-tests were used to compare patients with or without delirium. AECc differences among delirium types were compared using Kruskal-Wallis tests.

RESULTS

AECc was significantly increased in delirious (n = 173, age 79.2±9.3 years, 46 % female) as compared to non-delirious (n = 204, age 72.9±13.1 years, 45 % female) patients in the delta (median, effect size of difference: 0.16 vs. 0.12, r = 0.28, p < 0.01) and beta band (0.11 vs. 0.09, r = 0.14, p = 0.04). These changes did not differ among delirium types (p > 0.05).

CONCLUSIONS

We found modestly higher delta and beta band AECc in delirium compared to non-delirious control patients, regardless of the presumed etiology.

SIGNIFICANCE: This study provides evidence for altered amplitude coupling as mode of impaired neuronal communication in delirium, the role of which should be investigated in future studies of neural network pathophysiology.