F8   HISTOLOGY AND HORMONAL ACTIVITY IN SENESCENT THINNING IN MALES

¹Price V.H.,  ²Sawaya M.E.,  ³Headington J.T.,  ⁴Ann Arbor, MI; ⁵Kibarian M.K.; ¹Dept. of Dermatology, University of California, San Francisco, Dept. of Dermatology,  ²ARATEC Clinics & University of Miami, Miami, Florida, ³Dept. of Dermatology & Pathology, ⁴George Washington University, Washington, D.C.

Senescent thinning of the scalp hair, or thinning that occurs after age 60, is poorly understood, and it is unclear whether this is a distinct entity of part of the continuum of androgenetic alopecia. In a previous study, young males age 18 to 30 with androgenetic alopecia had higher levels of 5a-reductase type 1 and 2, more androgen receptors, and lower levels of cytochrome P-450 aromatase in hair follicles in the frontal region of the scalp than in the occipital region. This study in males with heir thinning are similar to androgenetic alopecia in young males.

Males who experienced the first onset of scalp thinning after age 60 were compared to age-matched males (controls) without a history of hair thinning. Four scalp biopsies, two from the frontal and two from the occipital scalp, were obtained for horizontal sectioning and bjochemical assay.

Histologic findings were primarily follicular downsizing rather than follicular drop out. Senescent thinning was indistinguishable from androgenetic alopecia in older males.

Biochemical analysis for androgen receptors, 5a-reductase type 1 and 2, and aromatase, in scalp biopsies from older males showed nearly a two fold decrease in levels  compared to levels in young males with androgenetic alopecia. In males over 60, androgen androgen receptor and aromatase levels  were low and comparable to scalp with and without thinning in both frontal and occipital regions. The 5a-reductase type 1 and 2 levels were higher in males with thinning hair than without thinning in both frontal and occipital regions. In males with thinning hair, levels were only slightly higher in frontal than in occipital scalp and the difference was not as great as in young men with androgenetic alopecia.

These findings suggest that senescent thinning is histologically similar to androgenetic alopecia, but biochemically different and may not be entirely androgen dependent.