Chronic stress as a precursor to malignant cancer and autoimmune disorders

Chronic stress dysregulates the hypothalamic-pituitary-adrenal (HPA) axis through the breakdown of glucocorticoid feedback mechanisms, including hippocampal GR-mediated inhibition and KCC2-dependent GABAergic regulation of CRH neurons. This essay synthesizes the literature on how sustained glucocorticoid elevation drives thymic atrophy via GR-induced apoptosis of double-positive thymocytes, which lack the antiapoptotic protein Bcl-2, alongside depletion of medullary thymic epithelial cells. The resulting impairment of negative selection contributes to autoimmune pathology and reduced tumor surveillance. Sex differences in these outcomes are examined through the opposing effects of estrogens and androgens on AIRE expression and thymic stromal support. Finally, the essay describes a self-reinforcing spiral in which thymic atrophy, chronic infection, dehydration-driven AVP amplification, and emotionally-processed illness symptoms feed back into HPA activation — transforming a homeostatic protective response into the principal threat to homeostasis.