The changing landscape of managing hair loss: a 30‐year perspective

Field: Medicine (Health Sciences)

Over the last 30 years, there has been an increasing interest of dermatologists and researchers in hair loss. This is manifested by an increase in the number of citations related to hair, from just few in 1991 to over 12000 in 2020. The 30 most active authors of articles related to alopecia in these 30 years were as follows: Bergfeld W, Betz RC, Blume-Peytavi U, Christiano AM, Clynes R, Duvic M, Happle R, Hoffmann R, Hordinsky M, Ito T, Jabbari A, Jimenez JJ, King LE, Lee WS, Mcelwee KJ, Messenger AG, Mirmirani P, Miteva M, Nothen MM, Paus R, Piraccini BM, Price VH, Rossi A, Rudnicka L, Shapiro J, Sinclair R, Sperling LC, Sundberg JP, Tobin DJ, Tosti A, Trueb RM and Vano-Galvan S (defined by the number of articles listed in Web of Science/Clarivate). These authors and many others contributed to the progress, which changed hair diseases from a neglected topic in dermatology to a fascination of many dermatologists. New developments in the differential diagnosis of hair loss may be attributed to a significant progress in histological evaluation of scalp biopsies, including the development of the horizontal sections of scalp biopsy specimens.1 Also, trichoscopy2 and the technique of trichoscopy-guided biopsy enriched the spectrum of diagnostic tools in hair and scalp diseases. Other non-invasive imaging methods are under development. A significant progress has been made in management of hair disorders. Androgenetic alopecia became at least partly reversible, when treated early. While topical minoxidil solutions are already in use since the 1980s, other forms of the drug were developed later. These include the minoxidil foam, which shows some benefit over the solution and the low dose oral minoxidil, which revolutionized the approach to treatment of androgenetic alopecia and other forms of alopecia in women and men.3 Newest data indicate the existence of genetic markers that may predict response to oral minoxidil.4 The introduction of 5-alpha reductase inhibitors to treatment of androgenetic alopecia in men and – after some controversy – in women marks another breakthrough in dermatology.5 Hair transplantation techniques improved over the recent 30 years, with follicular unit extraction (FUE) becoming the accepted standard. The development of first robotic hair restoration system started a new era in hair restoration in androgenetic alopecia. The last 30 years were marked by a search for an effective therapeutic option in alopecia areata. Before 1991, the treatment was based on topical immunotherapy and glucocorticoids (topical, oral and intralesional). Later developments in glucocorticoid therapy include the use of clobetasol under occlusion and high-dose methylprednisolone pulse therapy. Cyclosporine was observed to cause hair regrowth in organ transplant recipients with alopecia areata 35 years ago.6 This led to further studies over the years, which confirmed its significant efficacy. Other immunosuppressive agents, such as methotrexate and azathioprine, were shown to be effective in some patients. The most recent developments focussed on the potential application of Janus kinase inhibitors (JAK) in alopecia areata. Clinical trial data are available for baricitinib, brepocitinib and ritlecitinib. Several studies are ongoing. Most probably, the JAK inhibitors will become the first group of drugs developed and approved for alopecia areata. In other hair diseases, the progress is less impressive. Several off-label treatments have been investigated and show some efficacy. This includes immunosuppressive treatments and retinoids for various types of cicatricial alopecia. Also, the search for a method to halt chemotherapy-induced alopecia is ongoing. Scalp cooling is a recent development with promising results. The last 30 years brought the identification of new entities. Frontal fibrosing alopecia, first described in 1994,7 shows an ‘epidemic’ rise in incidence. Other newly described diseases are the vulvovaginal–gingival–pilar syndrome, fibrosing alopecia in pattern distribution and new entities in the spectrum of ectodermal dysplasias or new patterns of hair loss induced by new drugs. Hair loss may be a symptom of systemic diseases, such as endocrine imbalances, systemic autoimmune diseases and malignancies. Methods for early disease identification of these cases have been developed. In 2019, hair loss was included in the classification criteria of systemic lupus erythematosus. It was not until the recent years, when it became widely understood that hair loss has a significant, negative impact on the quality of life. It also may be the cause of depression and anxiety. These phenomena were studied in most detail in alopecia areata, but are also an essential factor in other forms of hair loss. The recent years brought a shift in understanding ‘hair loss’, from a condition which is restricted to hair and its immediate biological environment to rather being a symptom associated with a high diversity of interacting (also systemic) factors. Hair diseases may be associated with several comorbidities. Men with androgenetic alopecia were found to be at increased risk of developing cardiovascular diseases and prostate hyperplasia. Alopecia areata is associated with an increased probability of developing the metabolic syndrome and other systemic diseases. Several studies are ongoing. Several classification systems were developed over these years to categorize various types of hair loss. One of the criticized, yet most widely used in an unchanged form, is the North American Hair Research Society proposed working classification of primary cicatricial alopecias from 2001.8 Also, the ‘christmas tree’ pattern hair loss included in one of the modified female androgenetic alopecia classifications found a stable place in dermatology. Several scoring systems were proposed to assess disease severity, with the Severity of Alopecia Tool (SALT score) being probably most widely known.9 A modernized version of the Ludwig scale for female androgenetic alopecia is a five-point visual analogue scale based on the perception of hair loss severity by comparing the patients' scalp to 5 standardized photographs of patients with female androgenetic alopecia of various degrees. The COVID-19 pandemic stimulated studies on issues related to hair loss. Several data indicate that men with androgenetic alopecia are at increased risk of developing severe COVID-19. This may be attributed to the fact that androgens facilitate SARS-COV2 entry to the cell through the ACE2 receptor. It was shown that SARS-CoV2 infection may cause transient telogen effluvium and trichodynia. The pandemic was also motivation to develop novel teledermatology solutions for patients with hair loss.10 In conclusion, the developments of the recent 30 years were based on the vast amount of knowledge from previous years. New developments in differential diagnosis, and, most importantly, in treatment of hair loss gave new hope to the patients and caused a raising interest in hair among dermatologists. None to declare. None to declare.