A study comparing androgenetic alopecia and senescent alopecia using microarray analysis demonstrated significant differences in the gene expression patterns, further corroborating that they in fact represent different entities: In androgenetic alopecia, genes required for anagen onset, epithelial signal to dermal papilla, hair shaft differentiation and anagen maintenance were downregulated, and genes for catagen and telogen induction and maintenance were upregulated; whereas in senescent alopecia, genes involved in epithelial signal to dermal papilla, actin cytoskeleton and mitochondrial function were down-regulated, while oxidative stress and inflammatory response genes were up-regulated.(1)
Androgenetic alopecia and senescent alopecia share the features of decrease in the number of anagen follicles and hair diameter, resulting in age-dependent progressive thinning of hair, which is why they have long not been considered as different entities by some experts, with considerable overlap further obscuring the delineation from each other. Nevertheless, they differ in age of onset (early vs. lat), distribution (patterned vs. diffuse) and pathophysiologic factors (increased vs. decreased 5-alpha-reductase activity).(2,3)
Ageing inﬂuences the diameter, surface topography, hardness, loss modulus, storage modulus and tactile perception of human hair. (4)
- Trüeb RM. Oxidative stress in ageing of hair. International journal of trichology. 2009;1:6-14.
- Kligman AM. The comparative histopathology of male-pattern baldness and senescent baldness. Clin Dermatol. 1998;6:108–18. [PubMed]
- Paradi M, Karnik P. Comparative gene expression profiling of senescent and androgenetic alopecia using microarray analysis. In: Trüeb RM, Tobin D, editors. Aging Hair. Springer (in preparation)[Ref list]
- Tang W, Zhang S, Zhang J, Chen S, Zhu H, Ge S. Ageing effects on the diameter, nanomechanical properties and tactile perception of human hair. International Journal of Cosmetic Science. 2016;38:155.