A key aspect of hair loss with age is the aging of the hair follicle.  Ordinarily, hair follicle renewal is maintained by the stem cells associated with each follicle. Aging of the hair follicle appears to be primed by a sustained cellular response to the DNA damage that accumulates in renewing stem cells during aging.  This damage response involves the proteolysis of type XVII collagen by neutrophil elastase in response to the DNA damage in the hair follicle stem cells. Proteolysis of collagen leads to elimination of the damaged cells and then to terminal hair follicle miniaturization.
The topical sensitizers, diphencyprone or squaric acid dibutylester, have been used in those suffering from recalcitrant alopecia areata or those with more than 50% hair loss. The goal of treatment is to create an allergic contact dermatitis of the scalp. This alteration in the immune response occasionally is accompanied by hair regrowth. The efficacy of the topical sensitizers has been demonstrated in both young children and adults, but it probably works less than half the time. Recent success using oral janus kinase inhibitors, including tofacitinib, ruxolitinib, and baricitinib, have been shown to be efficacious in severe, extensive alopecia areata in adults, but long-term therapy has potential side effects. The durability of response to these medications is variable, and most patients experience recurrence of hair loss after discontinuation. Perhaps topical therapy with these types of drugs may be available in the near future.
Hi Adam, this certainly sounds most likely to be the autoimmune disorder Alopecia Areata . Frustratingly, this condition is something of an enigma, in that medical science has not yet confirmed its cause, though triggers such as shock, trauma and allergies are known, and much of the circumstances of the disorder - including whether it will spread or when it will stop and if it will restart again - are unable to be predicted. Often this condition will clear up by itself but treatment is also available to help speed up the process. If you would like personalised advice, please contact us to arrange a free consultation at our Central London or City of London hair loss clinics, or if it is easier due to your location, you can complete an online consultation form and one of our hair loss specialists will be in touch to go through everything with you.