j. Cosmet. Sci., 50, 111-131 (March/April 1999) Preprints of the 1999 Annual Scientific Seminar (Thursday Program) May 6-7, 1999 Chicago Hilton & Towers Chicago, IL 111

112 JOURNAL OF COSMETIC SCIENCE HAIR CARE AS WE MATURE Marty Sawaya, M.D., Ph.D. Aratec/University of Miami, P.O. Box 7, Ocala, FL 34478-0007 It is known that we are born with all the hair follicles that we are going to have and that with age, physical health, environmental aspects, etc, these hair follicles can change. As the human body ages, many processes slow or do not proceed at the same rate as in younger years. Hair growth is a good example, since hair is such a dynamic structure growing each day at rates of 0.35-0.45 mm. As the hair follicle ages, fewer and smaller hair shafts are produced at a slower rate. Pigment cells also age, ceasing the manufacturing of eumelanin and pheomelanin. An important aspect that does not change with age is the contribution that scalp hair plays on ones personal "self image". As we get older (50 yrs) men and women may not have as much hair as people in their 20's and 30's, and it is important to optimize the appearance of hair. This is best achieved by developing an understanding of hair biology in mature hair follicles and selecting hair grooming products and procedures with these aspects in mind. Biology of Hair with Maturation: With age, hair follicle numbers and the amount of keratin proteins which make up the hair fiber of "hair" starts to decrease after the age of 50 yrs. All hair follicles are formed early in human development, with eyebrows, upper lip, and chin follicles present at week 9 and the full complement of hair follicles being present by week 22 of development. After this time period, the total body number of 5 million follicles is present, with 1 million on the head, which approximately 100,000 are on the scalp. No other follicles are formed during life. As body size increases, the number of hair follicles per unit area decreases, with continued hair follicle density decreasing on the scalp with balding. As men and women age, the hair growth rates slow to 0.35 mm/day, preventing a given hair from growing as long during the anagen phase. The diameter of hair produced is smaller, which leads to smaller, thinner, finer hairs. These hairs usually are less resistant to adverse effects from grooming and have less body, less elasticity or tensile strength, etc. It is still uncertain if the changes taking place in maturing hair have any similarity to the miniaturization phases that take place in androgenetic alopecia. Current studies are taking place in men ages 60 and over to determine if histological and biochemical evidence supports this theory. Also, it is known that men and women have many of the same enzymes and steroid receptor systems in hair follicles but that the levels of these factors is different between men versus women.