TY - CHAP M1 - Book, Section TI - Overview of Aging A1 - Baumann, Leslie PY - 2015 T2 - Cosmeceuticals and Cosmetic Ingredients AB - There are two main processes of skin aging, intrinsic and extrinsic.1 Intrinsic aging is controlled by genes. The genes that contribute to skin aging have not yet been elucidated although some are thought to play a role in aging. Extrinsic aging is caused by external factors such as smoking, excessive use of alcohol, poor nutrition, and sun exposure, which in many cases can be reduced with effort. It is believed that as much as 80 percent of facial aging can be ascribed to sun exposure (extrinsic aging).2 It is also speculated that some factors implicated in extrinsic cutaneous aging may impact the intrinsic aging process.3 SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - dermatology.mhmedical.com/content.aspx?aid=1174544515 ER -