Under the surface: Low cardiac vagal tone and poor interoception in young adults with subclinical depressive symptoms.

Introduction: Depressive symptoms are associated with alterations in central and autonomic nervous system activity, including misperception of bodily activity (e.g., low interoception), somatic symptoms and decreased vagally mediated heart rate variability (vmHRV). However, there is a lack of studies that examine both perception of bodily activity and autonomic function in depression. The present study investigated the association between interoception, vmHRV, and subclinical depressive symptoms.

Method: Eighty-eight students were enrolled and vmHRV was calculated from a 5-minute resting electrocardiogram. Interoceptive accuracy (heartbeat tracking task; heartbeat discrimination task), interoceptive sensibility (Body Perception Questionnaire), and depressive symptoms (Depression, Anxiety and Stress Scale - 21 Items) were assessed.

Results: Interoceptive accuracy and sensibility positively correlated with vmHRV and negatively correlates with depressive symptoms. Cluster analysis performed on vmHRV, interoceptive accuracy, and sensibility provided two clusters: the first characterized by a pattern of low interoceptive accuracy, sensibility, and decreased resting vmHRV, the second characterized by an opposite pattern. Regression analyses showed that the first cluster was characterized by significantly higher depressive symptoms compared to the second (β = 1.97; p = 0.04), even after controlling for sex, BMI, anxiety, and stress levels.

Conclusions: Subclinical depressive symptoms are associated with a consistent impairment in the perception and interpretation of bodily activity and altered regulatory function of the autonomic nervous system. The present results suggest that the alteration of brain-body communication could be involved in subclinical depressive symptoms. Early identification of such alterations could help with targeted preventive strategies.