Oftentimes when people are first diagnosed, it’s because they find a bald spot which may lead them to believe that alopecia areata is specifically about their hair and the loss of it. However, alopecia areata is more about the immune system than it is about the hair follicle itself.
Certain portions of the human body have ‘immune privilege,’ meaning they are able to tolerate the introduction of foreign substances without eliciting an inflammatory immune response. Our hair follicles (primarily the epithelium surrounding the hair follicles) are part of the skin immune system. Our skin immune system is constantly signaling and talking to keep our lymphocytes at bay — letting them know that they are, indeed, supposed to be there. Read more…
In 1995, the Mayo Clinic released a study on the incidence rate of alopecia areata in Olmsted County, Minnesota consisting of 292 participants who were newly diagnosed with alopecia areata from 1975 to 1989. This study set the only known lifetime risk for alopecia areata at 1.7%. (Lifetime risk means the risk of developing a disease during ones lifetime.) A newer study, with 530 qualifying participants, was recently released accessing the same data parameters but from 1990 to 2009 to document the most current lifetime incidence risk. They found that the risk of a person developing alopecia areata during their lifetime has increased to 2.1%.
Nearly 6.7m people in the U.S. (over 149m worldwide) will develop alopecia areata in their lifetime.
At 2.1%, the cumulative lifetime incidence of AA from this recent 20-year period was slightly higher than 1.7% observed in the older study. Similarly, REP data analyzed in studies of other autoimmune-associated diseases have shown that incidence of rheumatoid arthritis and systemic lupus erythematosis have also increased in the region in recent years. These data do not refute the hypothesis that autoimmune disease incidence maybe rising, generally.
The exact pathophysiology of alopecia areata remains unknown. The most widely accepted hypothesis is that alopecia areata is a T-cell–mediated autoimmune condition that is most likely to occur in genetically predisposed individuals.
Much evidence supports the hypothesis that alopecia areata is an autoimmune condition. The process appears to be T-cell mediated, but antibodies directed to hair follicle structures also have been found with increased frequency in alopecia areata patients compared with control subjects. Using immunofluorescence, antibodies to anagen-phase hair follicles were found in as many as 90% of patients with alopecia areata compared with less than 37% of control subjects. Read more…