Autonomic and limbic system functioning, early life stress, and depressive symptoms in adolescence
Background Adolescence is a critical window for autonomic and limbic development and a period of elevated risk for depression. Although autonomic and limbic system function have, independently, been linked to depression, they are coupled and both influenced by early life stress (ELS). We do not yet know, however, whether the association of autonomic activity and limbic connectivity with depressive symptoms differs across dimensions of ELS. Methods Participants were 93 youth (Mage = 12.3) who completed the Trier Social Stress Test (TSST) with continuous electrocardiogram (ECG) recording. ECG-derived high-frequency heart rate variability (RespHRV) was assessed across the baseline, reactivity, and recovery phases of the TSST. Hippocampal-amygdala connectivity was estimated from resting-state data acquired just before the TSST using the Tian atlas. We tested whether RespHRV recovery and connectivity were jointly associated with depressive symptoms and whether ELS dimensions of threat, unpredictability, and deprivation moderated this association. Results Greater RespHRV during recovery was associated with more negative right hippocampal tail-left lateral amygdala connectivity (β = −0.42, q = 0.002). In a joint model, threat (β = −0.34, p = .007) and deprivation (β = −0.36, p = .009 independently moderated this association. Specifically, more negative connectivity predicted fewer symptoms when paired with weaker RespHRV recovery in high-ELS youth, but with stronger RespHRV recovery in low-ELS youth. Conclusions Whether autonomic-limbic coupling buffers or confers risk for depression depends on the early environment in which it developed.