The Effects of Aging on Hair–More Than Just Amount 486 • Changes occur both at puberty and around age 45–55. These changes at middle- to advanced age are more noticeably significant for women than for men due to menopause. • Lipid changes affect hair greasiness, shine, softness and smoothness. All four of these properties are decreased significantly by menopause and age. Conclusions - Hair Diameter vs. Age Female Hair Diameter vs. Age • The largest study on female hair diameter versus age (Otsuka and Nemoto, n 18,000 Japanese females) suggested that hair diameter versus age increases to a maximum near age 40, while the second largest study by Robbins and Dawson et al. (n 1,000 Caucasian females) concluded the maximum near age 45. If menopause and its consequent physiologic changes are involved in the age for maximum diameter and subsequent changes, we would expect the peak to be closer to age 45. However, the difference between these two studies might also be explained by a geo-racial or population effect. Additional studies will be required to resolve this issue. However, since the median age for menopause occurs at approximately age 50–51 in women of most industrialized countries including Japan and the United States,17 we lean toward the effects of menopause being critically involved, and therefore suggest that the peak age for diameter for both populations is likely closer to the mid-forties. • A number of smaller studies are in reasonable agreement with the conclusions of these two larger studies, indicating that the age of maximum diameter for females is near the forties. • Post-menopausal women were shown to have significantly lower hair fiber diameters than pre-menopausal women for the frontal but not the occipital scalp region. This effect was shown to be independent of age, suggesting an impact of the hormonal effects of menopause on hair diameter.