http://onlinelibrary.wiley.com/doi/10.1111/bjd.13230/full
Androgenetic alopecia (Androgenetic Alopecia) is the most common type of baldness in men. The balding process is associated with the gradual miniaturization of hair follicles and successive hair loss. However, the relative contributions of hair density and diameter to Androgenetic Alopecia are still unclear.
Objectives
Hair density and hair diameter were investigated in Japanese men with or without Androgenetic Alopecia to elucidate the importance of these factors in the balding process.
Methods
Male Japanese subjects with or without Androgenetic Alopecia (
n = 369) were included in this study. Hair appearance at the vertex was evaluated by comparison with a series of standard photographs. Hair density was measured using a phototrichogram-based videomicroscopy technique, and hair diameter was assessed by comparison with a series of calibrated threads on the phototrichogram image.
Results
All subjects with Androgenetic Alopecia were ≥ 25 years of age. The mean percentage of thick hairs (> 80 μm) in all subjects with Androgenetic Alopecia was significantly lower than that in subjects without Androgenetic Alopecia aged ≥ 25 years (
P < 0·01), but the mean percentage of vellus hairs (< 40 μm) in subjects with Androgenetic Alopecia was significantly higher (
P < 0·001). By contrast, the mean density of the hair in all patients with Androgenetic Alopecia did not significantly differ from the density of those without Androgenetic Alopecia aged ≥ 25 years. However, the mean density of the hair in subjects without Androgenetic Alopecia aged < 25 years was significantly higher than that of both subjects without Androgenetic Alopecia aged ≥ 25 years (
P < 0·001) and all subjects with Androgenetic Alopecia.
Conclusions
Hair loss in men with Androgenetic Alopecia results mainly from the miniaturization of hair follicles rather than the loss of hair (shedding), at least for individuals who are ≥ 25 years of age and present with Androgenetic Alopecia.
