Question

Age is also a factor in chronic disease

Answer 1

Age is the main risk factor for the prevalent diseases of developed countries: cancer, cardiovascular disease and neurodegeneration. The ageing process is deleterious for fitnessAgeing as a disease risk factor can be thought of as the accrued effect of a finite number of evolutionarily conserved pathways. These pathways either have been selected for a specific beneficial function in earlier life, for instance DNA repair, and, as a side effect, actively contribute to the ageing process, or come under weakening evolutionary pressure later in life and therefore accumulate mutations with deleterious effects in aged organisms.