Alopecia areata was more common in black and dark brown hair than light brown and blond hair, supporting an association between the disorder and natural hair color, according to a study. “Alopecia areata has been observed to selectively involve pigmented hairs while sparing adjacent white hairs,” researchers wrote. “Following AA, regrowth of white hair is often seen in areas that were previously filled with darker hair.” Using the UK Biobank, researchers conducted a matched, case-control study. Of 502,510 white individuals reviewed for inclusion, 1,673 cases of alopecia areata (AA) were identified. Each was matched to four control subjects by age and sex, and each participant was asked what their natural hair color was. Those with dark brown and black hair were significantly more likely to be diagnosed with AA than light brown hair (dark brown hair: aOR = 1.26; black hair: aOR = 2.97. Individuals with blond hair were less likely to be diagnosed with AA than those with light brown hair (aOR = 0.69), and those with red hair did not have a significant difference in AA diagnosis rate compared with those with light brown hair (aOR = 0.94). “These findings support and expand on the previously hypothesized association between AA and hair pigmentation,” the authors wrote. “The mechanism through which darker pigmentation is associated with AA remains unknown. However, our findings suggest that investigations into the commonalities between mechanisms of hair pigmentation and autoimmunity or immunity that targets melanogenesis-associated proteins may illuminate this very common but poorly understood disease.” Source: https://jamanetwork.com/journals/jamadermatology/article-abstract/2777019?