Brain-heart decoupling in somatic depression: Desynchronization between salience network neuropsychological connectivity and heart rate variability

Somatic depression is a distinct subtype of major depressive disorder, with a poorer response to treatment, an elevated risk of suicidal behaviour, and a worse prognosis. Interoception, the sense of internal bodily signals, is related to somatic symptoms. However, the underlying pathophysiological mechanisms of body brain communication remain unclear. 293 depressed patients (145 with somatic symptoms and 148 without), and 160 healthy controls underwent magnetoencephalography during a resting state. Both the intra- and inter-network neural oscillation patterns of the salience network, were computed, alongside and heart rate variability (HRV) as a measure of autonomic function. Individuals with somatic depression exhibited lower HRV, accompanied by theta hyper-connectivity within the salience network. Although higher theta connectivity was linked to increased HRV in controls, this correlation was attenuated or even reversed in patients with somatic depression. Our findings identify a specific pattern of brain-heart decoupling in somatic depression, characterized by disrupted communication between salience network theta oscillations and autonomic cardiac regulation. This provides novel neuroimaging evidence for body-brain communication deficits in a clinically important depression subtype.