Types of hair loss

Alopecia areata (AA)

This type of alopecia is an autoimmune condition that causes patchy hair loss i.e. a single bald patch or extensive hair loss in patches. 

An autoimmune disease occurs when your immune system mistakenly attacks parts of the body that it confuses for something foreign.

Alopecia areata often starts suddenly, recurs frequently and affects men, women and children.   

AA is linked to obvious skin disorders or systemic diseases like systemic lupus erythematosus (SLE), syphilis, Addison's disease, cancer and vitiligo (a disorder in which the immune system destroys the body’s pigment cells, causing white patches).

Alopecia areata usually starts as a single coin-sized smooth bald circle or some thinning that your hairdresser may incidentally notice when you go for a haircut.

These bald patches usually regrow in three to six months without treatment.

Androgenetic Alopecia (AGA)

Androgenetic Alopecia (male or female pattern baldness) is the most common type of progressive hair loss, which entails thinning hair to an almost transparent state. It is believed to be hereditary from either or both parents.

Did you know that AGA affects more than 50% of men over the age of 50 and around 50% of women over the age of 65, according to the US National Library of Medicine?

Several genetic and hormonal factors cause AGA.

Of these, the main hormone responsible for androgenetic alopecia in both men and women is dihydrotestosterone (DHT), which induces a change in the hair follicles, resulting in hair loss.

In men, the typical pattern of AGA hair loss entails a receding hair line with loss of hair from the top and front of the head in a characteristic "horse shoe" pattern.

Women with AGA usually have thinning hair at the crown of the head, but keep their frontal hairline.

Because androgenic alopecia permanently damages the hair follicles, the resulting hair loss is irreversible.

Less common or rare types of hair loss include:

• Alopecia universalis (hair loss on entire body including pubic hair), which affects less than 1% of cases;
• Alopecia totalis (AT), a more advanced form of alopecia areata that affects up to 5% of AA patients, resulting in total loss of all hair on the scalp;
• Alopecia barbae is a type of AA localised to the beard area, which can be a single bald patch or more extensive hair loss over the entire beard; 
• Traction alopecia (thinning from ponytails or tight hair braids). This occurs when hair is subjected to excessive pulling or tension on hair shafts. Prolonged traction alopecia can prevent new hair follicles from developing and cause permanent hair loss.
• Anagen effluvium Chemicals used in radiation or chemotherapy to treat cancer generally causes this type of hair loss, which may initially be patchy but progress to total alopecia.  It is fortunately usually temporary, as hair grows back within six months after stopping medication.
• Telogen effluvium This affects women more often, causing a general thinning and temporary loss of up to a third of a person’s hair. Many factors may trigger it such as exam stress, surgery, pregnancy, crash diets and divorce or loss of a loved one.  Telogen effluvium usually occurs a few months after an incident. It needs no treatment as hair growth starts normalising after three to six months.
•  Scarring alopecias (cicatricial alopecias), refers to a group of rare disorders which cause permanent hair loss.  

Central Centrifugal Cicatricial alopecia (CCCA)

A condition sometimes referred to as “follicular degeneration syndrome” and “hot comb alopecia” is most commonly seen in African America women and is sometimes confused with female pattern hair loss, especially at the onset.

The disorder progresses slowly, beginning at the crown and advancing to the surrounding areas. Researchers suspect the condition may be related to chemical processing, heat and the use of 'hot combs', relaxers, tight extensions, weaves, occlusive ointments or greases or chronic tension on the hair. Other proposed causative factors include fungal or bacterial infections, autoimmune disease, type 2 diabetes and genetics. 

Read more: 

Signs and symptoms of hair loss 

Alopecia from Natural Medicines  

Causes of hair loss 

Sources

1. American Academy of Dermatology, https://www.aad.org/public/diseases/hair-and-scalp-problems/alopecia-areata
2. Derm Net NZ http://www.dermnetnz.org/hair-nails-sweat/alopecia-areata.html
3. Healthline.com http://www.healthline.com/health/male-pattern-baldness#Overview1
4. Alopeciaonline http://www.alopeciaonline.org.uk/androgeneticalopecia.asp
5. Medicinenet.com http://www.medicinenet.com/hair_loss/article.htm#hair_loss_facts
6. US National Library of Medicine
7. North American Hair Research Society