Types and causes of hair loss

The most common types of hair loss are:

  1. Hereditary hormonal hair loss or androgenic alopecia
  2. Spot baldness or alopecia areata
  3. Diffuse hair loss or diffuse alopecia

1. Androgenic hair loss

Androgenic hair loss is often described as hereditary hair loss. It is caused by the hormone DHT (dihydrotestosterone). Hair loss brought about by this is most commonly thought to be genetic. If there is a lot of DHT in the scalp and a hereditary sensitivity to it, the hair's growth phase is shortened. A bald person does not therefore have fewer hair follicles than someone with a full head of hair, but the hair’s growth phase is so short that it is almost invisible on the outside. The result is that the hair follicles wither away gradually, which is down to the sensitivity to DHT. The growth phase (called the anagen phase) lasts from 2-5 years under normal conditions. With hereditary hair loss, the hair can no longer develop fully and falls out, sometimes as hardly visible fluff. Interestingly, hair on the nape of the neck is resistant to DHT, and it is often used in hair transplants on the top of the head!

Androgenic hair loss often begins with the formation of a receding hairline or a tonsure and at the advanced stages, it results in baldness. But a bald person has just as many hair roots as someone with a full head of hair. The hair is just so short that it is almost completely invisible.

In principle therefore, there is the hope that even hair roots in bald people can be reactivated. This process is however very slow and requires a great deal of patience. Hair cannot grow back within 4 weeks – if at all – as the resting phase (called the telogen phase) of the hair lasts up to 4 months.

The success of hair growth preparations or those against hair loss can therefore only be realistically assessed after 4-6 months.

How is DHT produced?

Dihydrotestosterone (DHT) is produced from the metabolism of testosterone. DHT is very important in the development of male embryos and in puberty in the development from boys to men. The exact functions and the importance of DHT after puberty have not yet been researched. Unfortunately, it does have the negative capacity to attack the hair follicles on the top of the head, which leads to hair loss.

2. Spot baldness

Alopecia areata is best known as spot baldness. This means a round localised bald patch.

Spot baldness is the most common hair loss pathology (approx. 1.5 million people in the UK suffer from it) and can occur at any age, but most commonly in the twenties or thirties. Usually, there is at least one bald spot on the hair-bearing area, which is why it is called spot baldness. There are often short broken hairs on the edge of the patch which are narrower along the edge of the strand. The bald spots are smooth, but the hair follicles remain. There may also be noticeable changes to the finger nails such as pits or ridges.

Causes of spot baldness

Until now, science has not entirely succeeded in establishing the causes of spot baldness. It is thought however that immune cells that should be taking care of fighting viruses and bacteria actually attack the cells in the hair follicles. This is therefore an autoimmune disorder. The hair is seen as a foreign body by the immune system and is subsequently attacked. This happens following an inflammation which interrupts hair growth and finally leads to hair falling out. In some people, these bald patches grow back without treatment and are therefore temporary. Hair loss can also continue, which can then lead to the loss of all hair (called alopecia totalis).

Studies have so far been unable to provide evidence for psychological causes. Therefore doubt regarding the connection between spot baldness and stress still remains. There may also be a hereditary factor as there is familial clustering in 10-25% of cases.

Treatment of spot baldness:

As described above, spot baldness is an autoimmune disorder. The body’s defence turns against its own hair follicles thus making hair fall out. Spot baldness is treated with what is called topical immunotherapy. This works as follows: a chemical (DCP) is administered to cause an allergic reaction, this then distracts the immune system and consequently hair loss stops.

Everyone has allergic reactions to diphencyclopropenone (DCP). DCP is not authorised as medication so can usually only be obtained from clinics. During the treatment, there may be different reactions (swelling of the lymph nodes, pigmentation changes). DCP is not a dangerous substance, but the therapy costs patients a lot of time and patience. Treatment is repeated weekly. Unpleasant aftertaste. My scalp becomes itchy, red and scaly. Success is not guaranteed with this form of therapy.

Another possible treatment is PUVA therapy. How it works: ultraviolet rays in combination with a drug which makes the skin more sensitive to light. Expert opinion on this method varies, as long term use is thought to increase the risk of contracting skin cancer. This method is therefore rarely used.

3. Diffuse hair loss

Diffuse hair loss (diffuse alopecia) is when hair density declines evenly over the whole head. A lot of hair stays in between fingers when running them through the hair. If more than 80-100 hairs fall out every day for several weeks, then this is can be classed as a pathological increase in hair loss. This type of hair loss is very common and occurs more frequently amongst women than men. Diffuse hair loss can occur following acute or chronic infections or stress. It is well known that some drugs can also lead to diffuse hair loss. Such hair loss can also be caused by disorders in the metabolism such as protein malnutrition (or a deficiency in amino acids), vitamin deficiency, hyperthyroidism or hypothyroidism, diabetes and other metabolic disorders. No single method of diagnosis is possible as many different factors could be responsible for diffuse hair loss.

The most effective treatment consists of finding the underlying disorder and remedying it permanently. The hair loss can stop within months.


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