Characteristics of nonbalding scalp zones of androgenetic alopecia in East Asians

Summary Background Hair is known to persist on the occipital and part of the temporal scalp in patients with androgenetic alopecia (AGA), but no quantified data about the follicular changes in such areas exist. Aim To evaluate the hair characteristics in nonbalding scalp areas in East Asian patients with AGA. Methods In total, 265 participants [211 patients with AGA and 50 healthy controls (HCs)] were enrolled. The patients were divided by the Basic and Specific (BASP) classification [four basic types (L, M, C, and U) and two special types (V and F)], and the hair in the occipital region and two sites of the temporal region were analysed by computer-assisted phototrichography. Hair density, hair width, number of each follicular unit, ratio of single to compound hairs and ratio of terminal to vellus hairs were examined. Results In the temporal region, a statistically significant (P < 0.05) decrease in hair density was observed in patients with C, U or F subtypes, and a significant (P < 0.05) decrease in hair thickness was observed in patients with the U subtype compared with HCs. In the mastoid and occipital areas, both hair density and hair thickness was significantly (P < 0.05) decreased in patients with the U subtype compared with HCs. Within each classification, hairs became generally thinner as the hair loss progressed. Conclusions Hair density and hair thickness of known nonbalding scalp regions showed some differences depending on the severity and the BASP subtypes in East Asian people with male pattern baldness.