171 Age-Related Changes in Scalp Hair Density

Olsen EA, Cote N and Canfield D

Hair density is a frequently used endpoint in clinical trials of hair growth promoters. However, little information is available regarding age-related norms in androgen or non-androgen dependent areas of the scalp to help put study results in perspective. We therefore evaluated hair density in three different age groups of Caucasian men in both the occipital (non-androgen dependent) and mid-scalp (potentially androgen dependent) regions. In the 18-25 year old age group (Group I), 10 men without a family history or any physical evidence of androgenetic alopecia (AGA) were compared to 10 men with either early signs of AGA or a male first or second degree relative with > III Hamilton-Norwood pattern of baldness. In the 35- 45 year old (Group II) and 55-65 year old (Group III) age groups, 10-12 men with Hamilton-Norwood IIIv or IV in each age group were compared to 10-12 men without any physical evidence of AGA. Hair density was determined in all groups from photomacrographs of hairs in 1 cm diameter circular target areas clipped to ~1 mm in length in each of the two scalp locations. In one subgroup, the hair count methodology was repeated monthly x 2 and compared with hair weight data collected from the same sites. Results:

Conclusions: The mean occipital hair density is similar in men with or without AGA in the 18-45 year old age group and is a reliable normal comparator for the mid scalp target area hair counts used in clinical trials of hair growth promoters in AGA. Hair counts and hair weights are both valid and reproducible measures of hair density.