Handbook of Age and Aging - Hardcoverby Bram McConnell (Editor) Age is a natural process of gradual change that begins in early adulthood, including physical and mental changes. Many body functions start to deteriorate gradually after the early middle age. Physiology, heredity, lifestyle, senescence, biology and other factors have an impact on the aging process. Cataracts and refractive errors, osteoarthritis, depression, chronic obstructive pulmonary disease, dementia as well as neck