White Hairs in Regrowing Areas of Alopecia Areata: Why do they Occur?
Alopecia areata is an autoimmune disease that causes hair loss. The precise cause is not clear although it is clear that the immune system is activated to attack the hair. The target inside the hair follicle that the immune system is “going after” is still being debated by researchers. It may be one target or may be several. Among the theories is that proteins involved in the pigmentation of hair follicles are involved. We call the process melanogensis and researchers are focused on whether melanogenesis‐related peptides are among the autoantigens in alopecia areata.
Alopecia areata may preferentially target ‘pigmented’ hairs
Clinically, we have come to understand that alopecia may preferentially affect pigmented hair and sometimes will leave any white hairs on the scalp unaffected. In extreme cases, a patient with a mixture of grey and colored hair will find that they go from having dark hair to stark white hair “overnight.” This is form of alopecia areata where the dark pigmented hairs fall out due to their attack by the immune system and the white hairs are unaffected.
White hairs may also be seen as hairs are trying to regrow in patients with alopecia areata. Small white hairs are commonly seen and this provides a nice example that the delicate hair has not yet figured out how to add color back into the hair. In other cases, the normal growing hair will lose it’s pigmentation at the bottom and start emerging from the scalp as a white color. That is shown here.
Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887