Depression as a systemic disease

Depression is now conceptualized as a systemic illness because of neurobiological mechanisms that explain how it influences other medical illnesses. Significant research has been conducted to explain the mechanisms by which depression increases the risk of, and complicates, already established medical illness. Biological processes as diverse as inflammation, neuroendocrine regulation, platelet activity, autonomic nervous system activity, and skeletal homeostasis are influenced by depression. In this review we aim to elucidate the mechanisms through which depression affects patients with heart disease, cancer, stroke, diabetes, and osteoporosis. These are conditions in which the interplay between depression and medical illness continues to be investigated.