Hair diameter versus hair density in male androgenetic alopecia
Hair diameter versus hair density in male androgenetic alopecia
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男性雄激素性脱发的头发直径与头发密度
DOI：
10.1111/bjd.13390
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Okuyama R
中科院分区：
文献类型：
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作者：
中村謙太;皆川茜;芦田敦子;古賀弘志;木庭幸子;奥山隆平;宇原久;Okuyama R
雄激素性脱发（阿加）是一种极为常见的疾病，影响两性，男性发病率高于女性。男性阿加的特征在于头皮的进行性、模式性脱发，并且通常开始于双颞衰退，随后是头顶秃头和中额脱发，保留枕部头皮。1，2脱发的外观主要受毛囊逐渐小型化和毛发脱落的影响;然而，尚不清楚哪些因素在脱发的发展中起主要作用。由于个体间头发厚度和密度的差异很大，许多受试者需要评估这些因素对秃头发展的贡献。然而，在以前的研究中，受试者的数量太少，无法得出确切的结论。在这一期的BJD中，Ishino等人3使用视频显微镜技术评估了300多名患有或不阿加的日本男性。他们拍摄了头顶头皮目标区域的超近距离图像，以免错过细而轻的毛发（毫毛）。此外，他们比较了患有阿加遗传病的男性和年龄匹配的没有阿加遗传病的男性的头顶毛发密度，因为随着年龄的增长，头皮毛发会变得更细更松。令人惊讶的是，在这项大型研究中，头顶头发的密度并没有随着秃顶而减少，而头顶头发的厚度却显著减少。因此，脱发是由于终毛转化为毫毛导致毛囊逐渐小型化，而不是由于脱发增加。据报道，在脱发的发展过程中，毛发生长期的持续时间从几年急剧缩短到几周或几个月。5毛发生长期缩短加速了毛发的更新，促进了毛发脱落，但不太可能显著降低毛发密度。此外，由于本研究仅分析了日本男性，因此需要检查其他种族中患有阿加的男性与不患有阿加的男性之间的头顶毛发密度是否相似。有几种药物可以治疗男性阿加，包括局部米诺地尔，口服芬氟拉明和度他雄胺。虽然秃头头皮的完全再生是不可行的，但据报道，这些药物显示出头发再生的显着改善，并增加头发数量以及头发厚度。6-8然而，如果在脱发的过程中头顶头发的密度保持不变，这些药物不太可能增加头发的总数。毛发外观的改善主要取决于毫毛向粗端毛的转化。临床检查可能会低估毫毛，因为重点
Androgenetic alopecia (AGA) is an extremely common disorder affecting both sexes, with a greater incidence in males than in females. Male AGA is characterized by progressive, patterned hair loss from the scalp, and commonly begins with bitemporal recession, followed by vertex baldness and mid-frontal hair loss, with sparing of the occipital scalp. 1, 2 The appearance of hair loss can be chiefly influenced by the gradual miniaturization of hair follicles and hair shedding; however, it is unclear which of these plays a major role in the development of baldness. Owing to wide variations in hair thickness and density among individuals, many subjects are required to evaluate the contributions of these factors to baldness development. However, in previous studies the numbers of subjects have been too small to draw firm conclusions.In this issue of the BJD, Ishino et al. 3 evaluated more than 300 Japanese males with or without AGA using a videomicroscopic technique. They took ultra-close images of a target area of the vertex scalp in order not to miss fine and light hairs (vellus hairs). Furthermore, they compared vertex hair density between males with AGA and age-matched males without AGA because scalp hair becomes finer and looser with age. 4 Amazingly, vertex hair density did not decrease with balding in this large study, whereas the thickness of vertex hair decreased significantly. Therefore, hair loss is attributable to gradual miniaturization of hair follicles that results from the transformation of terminal hairs into vellus hairs, rather than to increased hair shedding. The duration of anagen was reported to shorten dramatically from several years to just weeks or months during the development of baldness. 5 The accelerated turnover of hair by shortened anagen promotes hair shedding, but is unlikely to substantially decrease hair density. In addition, as this study exclusively analysed Japanese men, it needs to be examined whether vertex hair density is similar between males with AGA and males without AGA in other races. There are several medications to treat male AGA, including topical minoxidil, oral finasteride and dutasteride. While complete regrowth of a bald scalp is not feasible, these medications were reported to show significant improvement in hair regrowth and to increase the hair number as well as the hair thickness. 6–8 However, these medications are unlikely to increase the total hair number if the density of vertex hair remains constant during the progression of balding. The improvement of hair appearance will depend mainly on the transformation of vellus hairs into thick terminal hairs. Clinical examinations might undercount vellus hairs because the focus