Many chemical mediators are involved, including cortisol and adrenalin from the adrenal glands, other hormones and neurotransmitters (such as serotonin and noradrenalin), and responses from the autonomic and immune systems. Depression thus leads to changes in the rest of the body, owing to long-term chemical imbalances in the systems that control the heart, the immune system, and metabolism.
这些区域有助于解读压力，决定恰当的反应。许多化学调节因子也参与其中，包括肾上腺分泌的血浆皮质醇和肾上腺素、其他的荷尔蒙和神经传递素（如血清素和去甲肾上腺素）、以及自律系统和免疫系统的反应。由于控制心脏、免疫系统和新陈代谢的系统中化学物质长期不平衡，从而发生抑郁症并导致身体其他部位的变化。