Loneliness is associated with altered interoceptive appraisal and attenuated prefrontal heartbeat-evoked potentials

Loneliness is associated with heightened affective sensitivity and increased vulnerability to stress, yet its psychophysiological mechanisms remain incompletely understood. Drawing on the three-dimensional model of interoception (Garfinkel et al., 2015), the present study examined whether loneliness is associated with variation in interoceptive sensibility (self-report), interoceptive accuracy (behavioral), and cortical processing of cardiac signals (heartbeat-evoked potential; HEP). Two primary hypotheses were tested: higher loneliness would be associated with lower interoceptive sensibility, particularly in dimensions involving emotional and regulatory appraisal of bodily states; and higher loneliness would be associated with attenuated resting-state HEP amplitude over fronto-central electrodes. Thirty-nine healthy adults completed the Multidimensional Assessment of Interoceptive Awareness (MAIA), heartbeat counting (HBC) and heartbeat discrimination (HBD) tasks, and resting-state EEG with simultaneous ECG recording. HEPs were analyzed using cluster-based permutation test, and source localization was performed using sLORETA. The first hypothesis was partially supported: four MAIA subscales - Not Worrying, Emotional Awareness, Self-Regulation, and Trusting - showed significant negative correlation with loneliness, whereas interoceptive accuracy was not significantly associated with loneliness. The second hypothesis was supported: higher loneliness was associated with attenuated late HEP amplitudes over left frontal electrodes, with source localization implicating the left dorsolateral cortex (DLPFC). The HEP-loneliness association remained significant after controlling for depressive symptoms and demographic factors (sex and age). These findings are consistent with a regulation-based account in which loneliness is associated with altered appraisal and impaired higher-order cortical processing of bodily signals, a pattern consistent with the hypervigilance model of loneliness.