Electrocardiography-derived autonomic profiles in depression and suicide risk with insights from the UK Biobank

Figures

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  Fig. 1. Heatmap illustrating the strength and polarity of linear relationships among HRV measures. BPM beats per minute, SDNN Standard deviation for intervals between adjacent beats, RMSSD Root mean square of successive differences between adjacent R-R intervals, pNN20/pNN50 Proportion of differences greater than 20 ms or 50 ms, MAD Median absolute deviation heart rate, SD1/SD2 Standard deviation in the two orthogonal directions of the Poincaré plot (for frequency domain), BR breathing rate, LF low frequency component power, HF High frequency component power, LFnu Normalized low frequency power, TP Total heart rate variability power.

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  Fig. 2. Distortion score plot for determining optimal number of clusters. The plot displays the distortion scores (within-cluster sum of squares) for K-means clustering, with the number of clusters (K) ranging from 1 to 10. The “elbow point,” indicating the optimal number of clusters, is observed at K = 4, where the rate of decrease in distortion significantly slows down. This suggests that 4 clusters provide a suitable balance between model simplicity and accuracy for this dataset.

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  Fig. 3. Anatomical and functional autonomous nervous system coping mechanisms. Visual representation of A low relative (LRS) cluster and B high relative (HRS) cluster. Chronic stress and depression are associated with a low heart-rate variability (HRV). A In the LRS cluster, rigid Priors based on depressogenic inferences lead to a hypervigilance state where a constantly increased metabolic need is anticipated (e.g, increasing breathing rate [BR]), which increases the prediction error. To minimize the prediction error, the parasympathetic tonus is elevated as a result from ongoing attempt to counterbalance an overactive sympathetic nervous system, guiding the body towards sickness behavior reflecting maladaptive physiological coping behaviors. B In the HRS cluster, the respiratory influences might dominate over the cardiac activity, eventually dampening the sympathetic activity, reflecting a top-down cognitive coping strategy. This figure was created with BioRender.com.