Science

What is alopecia, commonly referred to as baldness? – Science and the future

Hair falls out, grows back slowly, this is alopecia. The reasons vary from patient to patient. Alopecia is a symptom of a pathology, a disorder. For doctors, there are two categories of alopecia: scarring alopecia and non-scarring alopecia. And according to this typology, the diagnosis may be telogen effluvium, the most common form of alopecia with multiple causes. Another case, the most famous, male pattern baldness, but also female pattern baldness, called androgenetic alopecia (AAG), is by far the most dangerous of all.

But in any case, the big question is whether regrowth is possible.

Hair, how do they grow normally?

Healthy hair has an average of 150,000 hairs. The part implanted in the dermis is called the hair follicle. At its base is the hair follicle, in which rapid cell division occurs. Each hair follicle produces up to 15 hairs in a lifetime.

The life cycle of hair goes through three phases:

  • the anagen, or growth phase, which allows hair to grow a few millimeters each week for a period of 2 to 7 years, depending on the person, their gender, or ethnicity.
  • catagen phase or hair bulb involution phase, which lasts 3 weeks.
  • telogen phase, the bulb rests for 5 to 12 weeks, after which the hair that has exfoliated from the bulb is removed.

80 to 90% of hair in the anagen phase is healthy hair, 10 to 20% is in the telogen stage, and finally a tiny portion (1 to 2%) of growth stops or is in the catagen phase before the cycle starts again to a new phase anagen.

Alopecia, what is it?

We naturally lose 80 to 100 hairs every day. Beyond 150 hairs a day, this may seem abnormal. This is called alopecia, either diffuse or patchy fall, sudden or over time. This may be irreparable, then we are talking about cicatricial alopecia, there will be no hair growth, because the follicle is irreversibly destroyed. On the other hand, non-scarring alopecia reduces, slows down the growth of the hair follicle, but the shedding phenomenon will be temporary, re-growth remains possible.

The attending physician, then the dermatologist, will question their patient in detail and examine his hair to establish a diagnosis. Because alopecia takes many forms and can have different causes.

The most famous of all is androgenetic alopecia.

Baldness is a generic word, but it often refers to androgenetic or androgenetic alopecia (AGA). It affects men more often than women. The frequency of this symptom also depends on ethnicity: men of European descent are more prone to baldness than men of Asian, Amerindian or African descent. Finally, with age, androgenetic alopecia becomes more common among the male population, reaching almost 80% of those over 70 years of age. In women, it affects one in five women around age 40 and one in four women around age 60.

According to men, the front hairline rises, the lobes or temporal lobes become thinner. In other cases, it is the upper part of the skull, called the top of the head, which at first and increasingly carries monastic vows. Before falling out, the hair had lost enough thickness and length to penetrate the surface of the scalp. He lost pigmentation, density, and after the fall, only a thin fluff remains – fluff, which in turn disappears. Dermatologists talk about the miniaturization of the hair follicle, which from cycle to cycle turns into fluff in areas affected by androgenetic alopecia.

Scales for measuring alopecia
For men, the Norwood-Hamilton scale. It was developed by Dr. B. Hamilton in the 1950s and later updated by dermatologist and micro-hair transplant surgeon A. T. Norwood. Norwood and Hamilton establish 7 stages of progression of male alopecia, during which hair density is measured in 3 areas of the skull: temporal, frontal lobes and crown (top of the skull).


© Keminists
Hamilton, a physician and anatomist by training, established the connection between the sex hormone, testosterone, and AAH. His observations in the 1940s focused on the inmates of an institution for the mentally handicapped in Kansas, USA. The use of castration to control these patients was common until the 1950s in several states in America.
For women, the Ludwig scale was developed in 1977 by Dr. Erich Ludwig, which classifies female androgenetic alopecia into 3 stages, which are fewer stages than the Norwood-Hamilton scale. The hair around the parting is gradually thinning. In stage 3, the top of the skull is completely exposed.

The Ludwig scale for measuring the progression of androgenetic alopecia in women is a simplified version. Photo: © Keministi.
© Keminists

Causes of androgenetic alopecia

Androgenetic alopecia occurs when two factors are combined:

– A genetic factor passed down to one or both parents and grandparents. Note that some of these genes are present on the X chromosome and are only passed down from the mother. Thus, baldness may be maternal heredity.

hormonal factor. The hair follicle is sensitive to androgen hormones that regulate its growth. It is these hormones that occur during puberty that affect our hair system: they modulate their thickness, their growth rate and their distribution in stereotyped areas. Among these androgens, dihydrotestosterone (DHT), a testosterone derivative, influences and speeds up the hair growth cycle. One of the drugs used to delay AGA, finasteride, attempts to reduce DHT by blocking the enzyme responsible for its production, 5-alpha reductase.

Less common scarring alopecia

In the case of scarring alopecia, the bare skin of the scalp is either the appearance of red spots or the appearance of smooth and shiny skin. The fall can be done along the outlined areas or even touch the entire hair. Hair follicles are destroyed. Re-growth can no longer occur.

These scarring alopecias are rare and are symptoms of autoimmune inflammatory or dermatological diseases such as lichen planus, lupus, folliculitis decalvans.

What is less known is that certain barbering gestures practiced daily can cause long-term scarring alopecia called traction alopecia. Therefore, it is necessary to be wary of too tight hairpieces or ponytails that injure the hairline, smoothing and combing.

Telogen effluvium, transient and reversible alopecia

This diffuse, sudden and profuse hair loss, but often less than 50% of the hair, is temporary. Re-growth is possible, this is non-scarring alopecia. It can fluctuate in cycles over several years. Telogenetic alopecia is more common than emblematic androgenetic alopecia. It would even make up a good share of consultations with a dermatologist. And why “telogen”? Because this hair loss occurs during the eponymous phase of the hair growth cycle.

Its etiology is highly variable. This frequent alopecia may result from pregnancy, certain medications, a vitamin-deficient diet, or psychological or physical stress (such as general anesthesia). Telogen effluvium can also be seasonal, with many of our hair cycles synchronizing in the spring and fall. The hair loss phenomenon can last up to three months and does not affect the overall hair volume. In the case of a longer period exceeding 6 months and a capillary mass that is thinning, a consultation should be made.

Whatever the type of alopecia, it is with the doctor and during the history taking, in other words, with an in-depth questioning and before any physical and biological examination, solutions will be found. Drug treatment, vitamin replacement therapy, possibly microsurgery, or perhaps from time to time.

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