IL6 and depressive disorder: In this work, we found that IL-6 is an independent risk factor of POD onset, thus, making more robust the theory of inflammation as crucial substrate of the great majority of age-related pathologies (cancer, osteoarthritis, neurodegeneration including Alzheimer disease and dementia, type II diabetes among other), syndromes (frailty, depression disorders), and conditions, such as sarcopenia and obesity.