Alopecia is an autoimmune skin condition that attacks hair follicles and results in hair loss. According to the National Alopecia Areata Foundation, this type of hair loss can impact specific areas of the body and range in severity.
The hair follicle is an organ in the dermal layer of the skin -- cells within the follicle interact with hormones and other factors to regulate hair growth.
A 2017 study in which biopsies of alopecia areata affected skin were analysed showed “a lymphocytic infiltrate in and around the bulb or the lower part of the hair follicle in anagen (active growing, 90% of hairs) phase.” While the hair follicle is stopped in this first phase of the growth cycle, the follicle itself is not destroyed (although this can occur with other forms of alopecia). Hair can grow back.
The condition is typically linked to genetics with contributing factors that include emotional or physical stress, infection, gut microbiota. A 2020 study, however, suggested that exposure to toxic metals such as thallium, arsenic, and mercury (including dental amalgams) can cause alopecia in humans.
Hair loss following Covid infection has been referred to ask “shock hair loss”. Anecdotally, it has impacted 1/3 of infected patients. Known medically as telogen effluvium (TE), this hair loss can be accompanied by ‘trichodynia’ (TR) or painful and burning sensations of the scalp according to a 2012 study. The study reported, however, the “complete resolution of TE or TR occurred in 91 of 101 patients, whereas 10 cases had persistent active disease at the time of study completion.”