Hair Loss : Scientific Explanation

There have been a lot of research in the field of hair loss and I have tried to describe the current understanding in this field. Questions and comments are welcome.

On the basis of cause, hair loss or alopecia can be divided into three basic groups

1. Male Pattern or Androgenic alopecia, by far the common balding.

2. Diffuse pattern alopecia usually caused by disease

3. Scarring alopecia where injury to scalp causes hair loss.

   
   

   More than 95% of hair loss in men is due to androgenic alopecia. For androgenic alopecia to occur, three conditions must be met,

   
   

   1.Genetic predisposition to balding:

   This is not as simple as it sounds. You may have a father with full head and brothers with some baldness but you have a clean pate. The inheritance is usually polygenic, meaning multiple genes and their expressions play a role in development of baldness.

   However, if every man in your family loses hair by thirty, there is a stronger possibility that you will follow suit. Genetic factors are non modifiable. You must live with them.

2. Androgens or Male Hormones:

All men and all women (YES!) produce male hormones. These hormones are generated in different quantities in men and women and typically the levels are much higher in males. This is also the reason why patterned baldness is much much more common in males than in females.

 The male sex hormone, Testosterone is converted to another product called Di Hydro Testosterone (DHT) which is presently considered the main reason for hair fall. The conversion of Testosterone to DHT is mediated by an enzyme called 5 alpha reductase. DHT progressively destroys the hair root in genetically susceptible hair by a process called “miniaturisation” which leads to baldness. Since back and side scalp hairs are resistant to DHT, they can be used for transplantation.

3.Time

Time or ageing is the third factor that plays arole in balding process. Nobody loses hair before puberty (because DHT is not present in the body) but after that, everybody loses some hair. The pace of hair fall vary amongst individuals but it takes approximately 10 hair cycles for a strong anagen hair to become velus hair. This process does not affect universal safe hair zone and body hair which continue to flourish and can be used for transplant.

Although much less important, let me discuss other causes of baldness as well. Diffuse thinning of hair may be caused by anemia, thyroid or other hormonal disorder, severe physical stress etc. A rare type of diffuse thinning called diffuse unpatterned alopecia may even involve permanent hair zone. On the other hand scarring alopecia could be due to injury, burn or skin conditions. Alopecia areata is a rare autoimmune disease in which hair are lost in bunches and body hair may also be involved.

  I hope it is now clear that change of water, tension and helmets are not the cause of your hair loss. And repeated shaving or oiling is not going to save them either. It is the hair root which is being destroyed that needs to be saved. In my next blog I will discuss the rationale, benefits and drawbacks of medical therapies for hair fall.