VIP and depressive symptom measurement: Our aims were to determine if VIP concentrations in peripheral blood plasma were negatively associated with symptoms of anxiety and depression in healthy individuals and to investigate potential relationships between plasma VIP and CNS measures of grey matter volume and resting-state functional connectivity within specific VIP-rich regions of emotion processing, namely the amygdala, hippocampus, parahippocampus, and orbitofrontal cortices.