The 12 types of alopecia (and their characteristics)

Hair is a biomaterial that develops in the skin of most mammals and, being a thin, plastic and elastic filament made up mainly of keratin fibers, it fulfills a key function at the biological level: protection. But obviously human beings, beyond this evolutionary importance, we have given it a very important aesthetic connotation.

Hence, everything associated with abnormal hair loss can cause concern in many people, who see baldness as one of the greatest aesthetic threats. And if we take into consideration that almost 50% of the population suffers from alopecia problems of greater or lesser severity, it is essential to talk about it and its nature.

Alopecia, considered a synonym for baldness, refers to the absence or abnormal loss of hair, affecting only the scalp or the entire body and occurring temporarily or permanently. Similarly, this abnormal hair loss can be triggered by many different causes and expressed differently as well.

Therefore, in today's article and in the hands of the most prestigious scientific publications, in addition to establishing the clinical bases of alopecia in terms of causes, symptoms and treatment, we are going to investigate the particularities of the different types of alopecia that exist. Let us begin.

What kinds of baldness are there?

Alopecia is a clinical term that refers to the absence or abnormal loss of hair. It is a concept considered synonymous with baldness which, in a country like Spain, the second with the highest incidence behind the Czech Republic, occurs in 42% of men. Thus, the scarcity of hair is a "problem" with a high prevalence, being more common in men than in women, although these, despite the myths that exist, can also present it.

Generally, we speak of alopecia when there is a noticeable absence of hair or when the hair loss exceeds 100 a day, since a loss of between 50 and 90 is what is considered normal. But beyond these oversimplified definitions, what is truly important is identifying the exact type of alopecia.

In this sense, a classification of the different forms of manifestation of baldness has been made, grouping them into two large groups, non-scarring and scarring, each of them having subtypes within. And without further ado, let's discuss them.

1. Non-scarring alopecia

Non-scarring alopecia is a group of forms of baldness that have the peculiarity that are not associated with a destruction of the hair follicle, better known as hair root. This hair follicle, located under the skin, in the dermis, is the place where the metabolic and mitotic activity is housed through which the constant growth of hair is made possible. When there is no destruction of this hair root, but there are functional changes, we will be facing one of the following types of baldness.

1.1. Male androgenetic alopecia

Androgenetic or androgenic alopecia is the most common form of baldness. In the case of the male, it is the one that affects 75% of men, generally beginning to show obvious signs from the age of 30-40, although the first signs begin in adolescence.

The main causes are the polygenetic inheritance of certain genes together with hormonal factors, specifically an action of male hormones on the hair follicles, which cause atrophy of the aforementioned until a notable loss of hair is observed.

1.2. Female androgenetic alopecia

Female androgenetic alopecia occurs in about 10% of women and its causes, like the male, respond to both genetic factors (inheritance of genes that increase predisposition) and hormonal, something that explains why it generally appears with the arrival of menopause and with the consequent decrease in female sex hormones. In this case, the hair loss is more diffuse (there is usually not a complete disappearance as in men) and the typical “recesses” are not observed, which are a characteristic feature of alopecia in men.

1.3. Alopecia areata

Alopecia areata is a type of baldness that, being the second most common form, is expressed by the appearance of rounded patches without hair in certain areas of both the scalp and other parts of the body due to an autoimmune disorder. It is a quite unpredictable form of alopecia, because although there are times when hair grows back in that area, there are other times when it does not. But in 8 out of 10 cases, after about a year, the hair grows back.

1.4. Diffuse alopecia

Diffuse alopecia is a type of baldness where, although there is a progressive and generalized loss of hair, this loss is not complete. That is to say, it is not a total baldness, but a shortage of hair that, although it is evident, it can be more or less intense. It is a form of hair loss, generally reversible, since diet and lifestyle play a very important role, as well as the taking or not of certain medications.

1.5. Traumatic alopecia

By traumatic alopecia we understand that type of baldness that responds solely and exclusively to controllable causes. And it is that hair loss that occurs due to bad styling habits or general hair care, nervous tics of pulling our hair (which, to eliminate, we should have the support of a psychologist) or by stress. Thus, it is a form of baldness that is not only reversible, but also preventable.

1.6. Universal alopecia

Universal alopecia is the most striking type of baldness, as it is based on a total loss of hair from the whole body, affecting not only the scalp, but the rest of body hair, eyelashes, eyebrows, etc. It has an autoimmune origin (such as areata), that is, hair loss occurs as a result of an attack by the immune cells of our own body on the hair follicles. But although this attack is aggressive, let us remember that being a non-scarring alopecia, the hair root is not destroyed, so it is a reversible situation.

1.7. Telogen effluvium

By telogen effluvium we understand abundant hair loss which, although reversible, occurs in a short period of time. Due to different causes (illnesses, stress, pregnancy, postpartum, side effects of medications, nutritional deficiencies ...), a group of hair follicles "skip" the hair growth phase, which is why this generalized hair loss occurs before weather. Even so, in most cases, the situation returns to normal in less than a year.

1.8. Fibrosing alopecia

Fibrosing alopecia is a type of baldness that, unlike the others, occurs more often in women. Also known as frontal alopecia since hair loss occurs in such a way that the hair grows more and more back (leaving more area in front), its causes remain unclear, but everything seems to indicate that it is related to menopause , so hormonal factors would be one of the keys.

1.9. Localized alopecia

Localized alopecia refers to that form of baldness where hair loss is concentrated in specific areas of the scalp. It is not a total baldness but there are the famous “bald spots, especially the crown.

2. Scarring alopecia

Scarring alopecia is a set of forms of baldness that have the peculiarity that yes they are associated with a destruction of the hair follicle previously mentioned. Due to an injury, the root of the hair has been destroyed, so that the hair, in that area where a scar has developed, will not be able to grow back. Depending on the origin of the wound that has led to this irreparable damage to the follicle, we find the following types of alopecia.

2.1. Primary alopecia

By primary alopecia we understand all that baldness that occurs with a destruction of the hair follicle as a consequence of illness own dermatological hair, with physiological and / or morphological alterations of the hair follicle that causes it to be damaged enough not to allow hair growth.

2.2. Acquired alopecia

By acquired alopecia we understand all that baldness that occurs with a destruction of the hair follicle as a result of an autoimmune disorder (or of unknown cause) in which the immune cells, due to a genetic error, attack the hair root so aggressively that the cells responsible for hair growth are destroyed.

23. Secondary alopecia

By secondary alopecia we understand all that baldness that occurs with a destruction of the hair follicle as a consequence of dermatological infections or physical-chemical damage. Thus, those alopecia that have their origin in bacterial infections (such as leprosy), viral infections (such as herpes), fungal infections (due to fungi, such as ringworm), protozoal infections (such as leishmaniasis), due to exposure are included. radiation or burns.