Introduction:

It is helpful to understand the hair growth and loss cycle before venturing into its causes. This cycle is one of the most fascinating aspects of the human body. The normal hair growth cycle lasts for nearly 2 to 3 years.

Each hair grows a centimeter per month in this phase. Ninety percent of hair on your scalp is growing at any point in time.

How do we account for the rest?

1. Nearly ten percent of hair on your scalp, at any one time, is in a resting phase. After 3 to 4 months, hair falls out and new hair will grow in its place.
2. Some hair is shed normally each day as part of this cycle. However, as extensive research tells us, some people experience excessive (more than normal) hair loss. Most hair loss of this type affects men, women and also children.

• The Growth of Hair:

Let us understand the hair growth cycle more comprehensively. In a circulatory system fluids pass through the dermal papilla for two purposes:

1. supplying hair structure with nourishment; and
2. removing cellular wastes and other unwanted products.

Usually a strong circulatory system is important since temporal and posterior branches of the carotid artery bring nutrients and amino acids to hair follicles. A build-up of cellular waste will adversely impact work of the dermal papilla. Most other contributing factors for normal hair growth are proper care of hair and scalp as well as a balanced and nutritional diet.

What is the core biological process in the cycle?

Hair growth is achieved through cell division (mitosis) of matrix cells of the hair bulb in an anagen growing cycle of follicular development. Cell mass increases usually and forces hair cells to move into the upper bulb. They harden or cornify to join other similar cells. The mitotic activity of the cells and synthesis of protein in the matrix goes on as long as hair grows. However, growth stops every one to six years and brings the onset of the catagen transition cycle.

The bulb begins to degenerate and all mitotic activity stops. Cells then go into a telogen resting cycle for about three months. Fortunately, for the dormant follicle, unless problems are present, will burst into anagen growing activity once again and overall production of hair starts again.

• Hormonal Imbalances

Hormonal problems can cause hair loss. How exactly does this happen? If the thyroid gland is overactive or under active, your hair may start falling out.

How can this be countered?

You need to treat thyroid disease. Let us give you a primer. Hair loss may occur if male or female hormones, known as androgens and estrogens, are out of balance. Correcting hormone imbalances may just stop your hair loss.

Most modern medical research also leans towards the theory that one of the primary instigators of hair loss is a hormone called dihydrotestosterone (DHT) and binds to sites on hair follicles. They appear to make the follicles go into their resting phase faster that causes hairs produced by these follicles to become progressively thinner after all successive growth cycles.

• Flip to the fairer sex

Many women notice hair loss nearly 3 months after having a baby. This is also related to hormones. At the most, during pregnancy, certain hormones with excessive levels cause the body to keep hair that normally falls out.

When hormones return to pre-pregnancy levels, the hair falls out and a normal cycle of growth and loss starts once again.

There are many medicines that cause hair loss. Hair loss also improves when medicine you are taking is stopped. Medicines that actually cause hair loss include blood thinners (also called anticoagulants), medicines used for gout, high blood pressure or heart problems, vitamin A (excessively taken), birth control pills and brain chemistry altering antidepressants.

There are certain infections that can cause hair loss. Fungal infections of the scalp can cause hair loss in children.

• Bad Hair Habits

The other reasons for hair loss are mentioned here. If pulling is stopped before scarring of scalp develops, your hair will grow back normally.

Scarring can eventually cause permanent hair loss. We can enumerate other ways in which this can happen.

• We list all of the treatments here

Hot oil hair treatments or chemicals used in permanents (also called “perms”) can eventually cause inflammation (swelling) of the hair follicle, that results in scarring and hair loss.

Many hair loss conditions are described as “effluviums”. Notably, they affect different parts of the hair growth cycle.

• Causes of Telogen Effluvium

It is interesting to understand how telogen effluvium, one of the most common forms of hair loss occurs.

There are different variations

1. Classic short-term TE happens to women soon after giving birth.
2. Called postpartum alopecia, a sudden change in hormone levels at birth is such a shock to the hair follicles that they shut down for a while. There can be some significant hair shedding, but a large majority of women regrow their hair quickly.
3. Also, vaccinations, crash dieting, physical trauma like being in a car crash, and having surgery can prove to be a shock to the system and a large proportion of scalp hair follicles also go into hibernation. Mostly, as environmental insult passes and the body recovers, TE subsides accompanied by new hair growth.

There are some drugs that can also induce TE, notably antidepressants. Mostly a switch to a different drug can effectively resolve the issue.

1. A chronic illness may also lead to TE. Among the two most common problems leading to TE are stress and diet deficiency. Dermatologists often believe chronic stress can eventually exert a negative effect on hair growth and lead to persistent TE.
2. Animal model research has provided evidence to back this claim up. There is indeed a definite link between stress, stark changes in hair follicle biochemistry, and more hair follicles entering a telogen resting state.
3. Diet deficiencies can also cause TE. Essentially, lack of minerals, vitamin, or essential amino acids can effectively cause TE, like people in third world countries where diets can be wholly deficient in one or more nutrients. Also, animal experiments provide supporting evidence.

• Alopecia Areata

This is the third most common form of hair loss. There are many reasons why AA occurs. But generally, AA has been regarded as a stress-induced disease.

This view is extremely common today, even among dermatologists, even though there is very little scientific evidence to support the view.

The whole phenomenon of AA is extremely complicated. How does this occur? Extreme stress can trigger AA in some people, but research indicates that genes can also be involved. There are probably several genes to make an individual a lot more susceptible to develop AA. The more genes a person has, the more likely AA is.

Researchers generally believe a wide range of contributing factors make someone even more susceptible to develop AA. Most hormones, allergies, viruses, and even toxins can contribute. There are probably several factors involved in AA activation in any one individual.

• Scarring alopecia (Cicatricial alopecia)

Hair loss condition known as scarring or cicatricial alopecia can be due to a number of causes; to enumerate a few:-

1. Developmental or hereditary.

2. Hair follicle infection (bacterial, fungal etc.).

3. Traumas like burns, radiation, chemical injury or mechanical injury.

4. There are neoplastic (cancer) conditions like squamous cell carcinoma, basal cell carcinoma, lymphomas or secondary metastases.

5. The dermis could be inflamed resulting in diseases like syphilis, tuberculosis, herpes zoster, sarcoidosis, pyoderma gangrenosum, cicatrical pemphigoid and morphea.

• Congenital Hypotrichosis

Hypertrichosis is usually categorized as either generalized or localized but age of onset and the site of growth can also be a basis of classification. Each of the generalized and localized types is further sub-divided into congenital and acquired sub-types. Hypertrichosis involves lanugo, vellus and terminal hairs.

Generalized acquired hypertrichosis (GAH) conditions are caused by drug intake and by underlying abnormalities. GAH induced by drugs is more common and needs to be separated from other forms of generalized hypertrichosis.

• Drug induced GAH

Among other medications, phenytoin, cyclosporine and minoxidil are better known among several drugs to cause significant generalized hypertrichosis.

How does phenytoin work? It induces hypertrichosis three months or so after its intake. Induced by phenytoin it affects more women than men and is more prominent on extensor aspects of limbs and less on the face and trunk.

Nearly 60% of patients treated with cyclosporine develop hypertrichosis within six months. It is generally thick pigmented hairs that appear on face, trunk and limbs.

There are some medications that are related to this ailment. Oral minoxidil and, to a lesser extent, topical minoxidil cause hypertrichosis after a few weeks of therapy. Face and extremities are the affected areas on the body.

Hair growth disappears within a year when these drugs are discontinued. To resolve this condition depends on hair cycling characteristics of the affected area.

• GAH due to underlying abnormalities

Exposure to chemicals, such as hexachlorobenzene induces hepatic porphyria and associated hypertrichosis.

There are head injuries that often result in hypertrichosis. Earlier this was attributed to phenytoin drug intake by the patient but later hypertrichosis was even in those with head injuries but people not on the drug. This explains why there are some who lose their hair and some do not after discontinuation of this drug.

Malnutrition and anorexia nervosa also cause hypertrichosis on limbs and trunks of some people. Hypertrichosis also occur in children with celiac disease and in dieting women when carbohydrates are omitted for a longer period of time.

Generally, AIDS infection also causes localized hypertrichosis, but a generalized form has also been observed. The mechanism for hypertrichosis development is unknown, but probably there are several contributing factors with a relation to malnutrition, metabolic changes, immunological deregulation and drug intake.

• Congenital Aplasia Causes

This is a birth defect. Aplasia cutis congenita, or congenital aplasia, is a developmental defect where, for reasons not understood, the skin does not fully form as an embryo develops.

Aplasia happens either in the womb or the baby is born with congenital aplasia.

• Triangular Alopecia

The cause is unknown, but believed to be genetic.

• Congenital Atrichia

While congenital atrichia is genetic and runs in families, it is also a gene defect that spontaneously develops in the embryo during pregnancy though the parents may not have the condition.

• Infectious Agents

Ringworm: Listed below are the causes of ringworm. The fungus Microsporum audouini is a very common cause of ringworm worldwide, but increasingly Trichophyton tonsurans can also cause tinea capitis, particularly in South American countries.

There are other fungi causing tinea capitis including Trichophyton schoenleinii, Trichophyton megninii in Southern Europe and Africa, and Trichophyton violaceum in the Middle East. Usually, the fungus Microsporum gypseum can generally cause tinea capitis.

Folliculitis:There are forms of folliculitis that are non-infectious like those caused by oils and greases applied to the skin that clog up the hair follicles, but folliculitis is generally due to a bacterial infection.

Extremely common is an infection of hair follicles by Staphylococcus aureus. “Hot tub folliculitis” is generally caused by Pseudomonas aeruginosa growing in inadequately chlorinated water. You can also have viral, fungal, or yeast induced folliculitis involving Herpes simplex, Herpes zoster, Pityrosporum ovale, Trichophyton rubrum and other causative agents.

Piedra:Black Piedra is due to the fungus Piedra iahortae and is mostly found in tropical countries while white piedra is due to Trichosporon beigelii and is found mostly in Europe and Southern parts of the USA.

Demodex folliculorum:This is caused by Demodex, a little worm-like creature that likes to live on skin and in hair follicles.

Seborrheic dermatitis:What are the cause of seborrheic dermatitis? The excess, rich sebum production in seborrheic dermatitis can trigger proliferation of skin flora.

The Yeast Pityrosporon ovale (also called Malassezia furfur) has increased in numbers with consequent increase in intensity of seborrheic dermatitis.

Excessive yeast proliferation causes irritation and inflammation. Although this inflammation is not specifically directed at a hair follicle, if hair follicles are in the vicinity of the inflammatory cells then they will still be adversely affected.

The hair follicles find inflamed skin as an unhealthy environment in which to grow. Seborrheic dermatitis may non-specifically cause diffuse hair loss.

This hair loss is reversible with reduction of inflammation intensity. Since seborrheic dermatitis can involve a proliferation over the course of years it is important to point out that seborrheic dermatitis is not infectious, you cannot catch seborrheic dermatitis.

When yeast is involved in seborrheic dermatitis it is from the skin of the affected individual. We all have yeasts of various types on our skin, the problem in seborrheic dermatitis is that yeasts grow to far greater numbers than normal.

• Hair Shaft Defects

Loose Anagen syndrome:

Why your hair is loose is definitely not known for sure, but root sheaths that normally surround and protect hair shaft in the skin are not produced appropriately in people with loose anagen syndrome.

What are the possible causes? It seems that because root sheaths are not fully formed there is a definite lack of adhesion between the hair shaft and root sheath and the hair fiber is poorly anchored in the hair follicle.

There could be a genetic problem behind loose anagen syndrome and the condition can definitely run in families, but there are also many isolated case reports with absolutely no family history.

Traction alopecia and trichotillomania:

How does this happen? The reason for the increase is Traction Alopecia, a hair loss condition caused by damage to the dermal papilla and hair follicle by repeated pulling or tension over a long period. It usually occurs in persons wearing tight braids, especially “cornrows” leading to high tension, pulling and breakage of hair.

Traction Alopecia also occurs due to the overprocessing of hair. Chemical treatment of hair with dyes, bleaches, or straighteners disrupts keratin structure in a manner that reduces tensile strength.

Additionally, the use of thermal or chemical hair straightening, and hair braiding or weaving are examples of styling techniques that place certain women at high risk for various “traumatic” alopecias.

Trichotillomania:

As in other diseases, the precise cause of trichotillomania is not known yet, but it is a mix of both biological and behavioral factors.

Intensive research has found a potential link between impulse control disorders, like trichotillomania, and brain chemicals that are called neurotransmitters.

How do these work?

They help most nerve cells in the brain to send messages to each other. Mostly an imbalance of chemicals can affect the way the brain controls impulses.

How does stress impact this syndrome?

It is also believed that stress can trigger the impulsive behavior, and that some people continue the behavior out of habit.

Mostly in some cases, people with trichotillomania suffer from mental disorders like depression or anxiety. This in turn suggests that a link exists between disorders and the development of trichotillomania.

Also the risk of developing trichotillomania is slightly higher in people who have relatives with the disorder, suggesting that a tendency for the disorder can be genetic.

Monilethrix

The precise etiology (cause) of monilethrix remains unclear. Researchers have not determined whether monilethrix is a disorder of the function or structure of the hair .

Genetic studies suggest that monilethrix is caused by a mutation (change in a gene) in keratin (hair protein). Essentially mutations in human hair basic keratins (hHb) genes hHb1, hHb3, and hHb6 were described with this disorder.

Research has mapped these genes to chromosome 12q13.

• Cuticle Stripping and Bubble hair:

Introduction:

The hair cuticle is a strong outer sleeve of dead and highly keratinized cells that overlap each other like fish scales along the length of the hair fiber. This protects the softer inner cortex structure of hair fiber from damage.

What impact does this have? Cuticle scales may become damaged and “flake up” if too much processing happens.

How do these additives work? For perms, straighteners, bleaches, and dyes to work the cuticle has to be opened up so that most chemicals can get to the hair cortex and rearrange chemical bonds in the hair structure, as with straighteners and perms, or to remove or add hair pigment, like with bleaching and dyeing. What happens then? The result is a diffuse “alopecia”.

If chemical induced damage is strenuous, physical processes can essentially alter the hair. Aggressive brushing, back combing, and grooming techniques putting a lot of physical stress on the hair fiber can cause the cuticle to flake and strip away. Long-term casual use of the hair dryer can damage the hair excessively.

When your hair is washed, some of it gets under the cuticle and into your cortex. If you dry your hair with more heat you warm the water up.

This makes water expand inside the hair and this pushes it outwards to leave spaces in the hair fiber.

In exteme cases the hair develops little bubbles inside, a condition termed “bubble hair”. These bubbles result in making the hair much weaker and likely to break off. If harmful physical processes are combined with harm chemical processes then you are in for double jeopardy – the problem is compounded.

Trichorrhexis nodosa

Causes of trichorrhexis nodosa may be congenital or acquired. Congenital trichorrhexis nodosa is very rare, but some people have naturally weak hair where the cuticle is not properly produced.

It is usually hereditary, runs in families, and it first develops at a very young age. It is only abnormal production of hair fiber that is irregular and brittle and can also occur in metabolic disorders such as those that involve abnormal urea synthesis, abnormal copper or zinc metabolism, or defective cysteine or sulfur incorporation into hair fiber (trichothiodystrophy).

Moreover, acquired trichorrhexis nodosa is quite common and develops further as a result of excessive hair manipulation and over-processing.

Excessive brushing, hairstyles putting constant stress on the hair, excessive washing, dying, and perming will disrupt the cuticle in focal areas along a hair shaft.

Usually, trichorrhexis nodosa is seen in people to overuse hot combs or permanent waves for effectively styling their hair. Only when the cuticle is removed from hair fiber only then does the hair cortex swiftly breaks down.

The causes of most known forms of hair loss have been covered in this article. To sum up, the major causes of hair loss are due to circulation, hormonal influences, genetics, and nutrition. Due to the extensive nature of this subject, research is ongoing and more intensive causes will be found at a latter date.

People who read above article also read the following...