133 The change of hair density and hair diameter with aging and androgenetic alopecia in Japanese male.

A. Ishino, T. Takahashi, J. Suzuki and M. Tajima Shiseido Basic Research Center, Yokohama, Japan

Androgenetic alopecia (AGA) is the most common type of baldness with vellus hairs and completely atrophic follicles. The duration of hair cycle of vellus hair is less than that of terminal hair. The balding process is usually gradual the miniaturization of hair follicle (vellus hair) and successive hair shading. Giacometti reported that the density of hair decrease with age. The contributions of population of miniaturized or lost hairs on the AGA progressing are still unclear. We investigate the hair density and diameter in Japanese male with or without AGA to discuss the relationships between these data and over all hair appearance. The subjects between 15 and 61 years old with (n=258) or without (n=123) AGA were studied. The subjects with AGA classified in classes III-vertex, IV, V or VI on the Norwood – Hamilton classification. The inspected alopecia scores were evaluated by comparing with the prevalidated reference scale from 1 (slightly bald) to 10 (bald). The vertical hairs in areas of 5 × 5mm were cut with scissors to record the images. The number of cutting hairs counted and the density of hair were calculated on the images. The hair diameter were calculated as the pixel numbers on magnified images. The hair density distributed from 136 to 312 cm-2 and slightly decreased with age after 40 years in nonbald subjects. The average of density on bald subjects is not significant difference from that on non-bald subjects. The distribution of hair diameter indicated that the remarkable peak were observed at 90 mm in 10’s-40’s of non-bald subjects. In non-bald 50’s , the peak were slightly shifted to thinner. In AGA, the peak at 80-90 mm were disappeared, but the ratio of vellus hair increased with the alopecia scores. It is concluded that the appearance of hair loss on the AGA progressing at least until the class VI on Norwood classification results from the miniaturization of hair follicle, but not from the hair shading. We therefore believe that the prolongation of anagen duration is important to improve AGA .