Alopecia

There are three types of excessive hair loss, clinically known as alopecia. They are discussed in detail below.

1. Auto-immune Conditions

Alopecia Areata

Alopecia areata is an autoimmune disease in which hair falls out from areas of the body, usually from the scalp, due to the body’s failure to recognize its own cells. The immune system subsequently destroys the hair follicles as though they were invaders.

The hair typically falls out in small, round patches about the size of a quarter. In many cases, the disease does not extend beyond a few bare patches. Often it causes bald spots on the scalp, especially in the early stages. In 1%–2% of cases, the condition can spread to the entire scalp (alopecia totalis) or to the entire epidermis (alopecia universalis).

Conditions resembling alopecia areata, and having a similar cause, occur also in other species.

There are two types: Scarring alopecia, where there is fibrosis, inflammation and loss of hair follicles, and Nonscarring alopecia, where the hair shafts are gone but the hair follicles are preserved, making this type of alopecia reversible.

No matter how widespread the hair loss, most hair follicles remain alive and are ready to resume normal hair production whenever they receive the appropriate signal. In all cases, hair regrowth may occur even without treatment and even after many years. It does not reduce life expectancy and it should not interfere with going to school, playing sports and exercising, pursuing any career, working, marrying and raising a family.

Causes

Alopecia areata is thought to be a systemic autoimmune disorder in which the body attacks its own anagen hair follicles and suppresses or stops hair growth. For example, T cell lymphocytes (white blood cells) cluster around affected follicles, causing inflammation and subsequent hair loss.

A few cases of babies being born with congenital alopecia areata have been reported, but these are not cases of autoimmune disease because infants are born without fully developed immune systems.

Alopecia areata is not contagious but it occurs more frequently in people who have affected family members, suggesting heredity may be a factor. Strong evidence of genetic association with increased risk for alopecia areata was found by studying families with two or more affected members. This study identified at least four regions in the genome that are likely to contain these genes. In addition, it is slightly more likely to occur in people who have relatives with autoimmune diseases.

Endogenous retinoids metabolic defect is a key part of the pathogenesis of alopecia areata. In 2010, a genome-wide association study was conducted that identified 129 single-nucleotide polymorphisms that were associated with alopecia areata. The genes that were identified include those involved in controlling the activation and proliferation of regulatory T cells, cytotoxic T lymphocyte-associated antigen 4, interleukin-2, interleukin-2 receptor A and Eos (also known as Ikaros family zinc finger 4) as well as the human leukocyte antigen. The study also identified two genes — PRDX5 and STX17 — that are expressed in the hair follicle.

Classification

Alopecia areata commonly involves hair loss in one or more round spots on the scalp.

Hair may also be lost more diffusely over the whole scalp, in which case the condition is called diffuse alopecia areata.

Alopecia areata monolocularis describes baldness in only one spot. It may occur anywhere on the head.

Alopecia areata multilocularis refers to multiple areas of hair loss.

Ophiasis refers to hair loss in the shape of a wave at the circumference of the head.

The disease may be limited only to the beard, in which case it is called alopecia areata barbae.

If the patient loses all the hair on the scalp, the disease is then called alopecia totalis.

If all body hair, including pubic hair, is lost, the diagnosis then becomes alopecia universalis.

Alopecia areata totalis and universalis are rare.

Alopecia Totalis

Alopecia totalis is the loss of all head hair. Its causes are unclear, but believed to be autoimmune. Usually appears in two types, either being a fairly sudden and complete loss of all head hair or being a slower form that originates as alopecia areata (patchy loss) and advances to complete scalp hair loss. In this sense it is sometimes associated with alopecia areata.

Causes

In most cases of alopecia totalis there is a small chance of hair recovery, however there have been cases of complete restoration. It is considered a genetic autoimmune condition that has an unknown trigger and can sometimes be “untriggered” for unknown reasons.


Alopecia Universalis

Alopecia universalis, or alopecia areata universalis, is a medical condition involving rapid loss of all hair, including eyebrows and eyelashes. It is an advanced form of alopecia areata.

Normally, sufferers are otherwise healthy, but are more likely than the general population to experience thyroid disease and vitiligo (patchy loss of skin color). Those with vitiligo may eventually develop AU over time. Many individuals with Alopecia Universalis are born with some hair but begin losing it very quickly.

Causes

Alopecia universalis can occur at any age and is believed to be an autoimmune disorder in which a person's immune system attacks the hair follicles.

Genetic factors may contribute to alopecia universalis as approximately 20% of those affected have a family member with alopecia. The disorder is inherited as an autosomal recessive trait. It is caused by a mutation in a gene dubbed HR in chromosome band 8p21.2 — the human version of the gene that is responsible for hairlessness in mice.

2. Adrogyn
genetic-mediated conditions

2. Adrogyn genetic-mediated conditions

Approximately 1.7% of the population will experience episodes of alopecia areata during their lifetime

Female-Pattern Baldness

Female-pattern hair loss, also known as androgenetic alopecia, is the most common type of hair loss in women. There is no known prevention for it.

In FPHL there is diffuse thinning of hair on the scalp due to increased hair shedding, a reduction in hair volume, or both.

Another condition, chronic telogen effluvium, also presents with increased hair shedding and is often mistaken for FPHL. It is important to differentiate between these conditions as management for both conditions differ.

FPHL presents quite differently from the more easily recognizable male-pattern baldness, which usually begins with a receding frontal hairline that progresses to a bald patch on top of the head. It is very uncommon for women to bald following the male pattern unless there is excessive production of androgens in the body.

Causes

In general, baldness occurs when the hair follicle shrinks over time, resulting in shorter and finer hair. Eventually the follicle does not grow new hair. The follicles remain alive, which suggests that it is still possible to grow new hair.

The reason for female-pattern baldness is not well understood but may be related to the following:

Aging

Changes in the levels of androgens (male hormones). For example, after reaching menopause, many women find that the hair on their head is thinner, while the hair on their face is coarser.

Family history of male- or female-pattern baldness.

3. Environmental Causes

Stress & Anxiety

Sometimes emotional or physical stress can lead to hair loss, which is a serious concern for most people and something they wish to reverse.

However, due to the length of the hair-growth cycle, people often only begin losing their hair weeks or months after the stressful event has occurred, and the hair loss can continue for several months afterwards. Luckily, hair will usually grow back on its own once the source of stress has been removed.

The good news for anxiety sufferers is that not all anxiety-related hair loss is permanent. If stress and anxiety are what caused your hair loss, then reducing that anxiety can help your hair regrow. Not all hair comes back after it is lost regardless of the cause, and your hair loss may be natural and not caused by anxiety. No matter what, you need to make sure that you are addressing your anxiety directly in order to both reduce the likelihood of anxiety-related hair loss as well as the anxiety you experience due to your hair loss.