There are a number of causes of hair loss. Among these are:
Traction alopecia is the loss of hair caused by physically stressing and putting tension on the hair. Certain hairstyling including hair weaving and corn rows that were done too tightly can cause this type of hair loss.
Alopecia areata, a disease of the body that causes hair loss, affects approximately two million Americans. Alopecia areata causes patchy hair loss. Two other forms of this disease are Alopecia totalis and alopecia universalis. Alopecia totalis is the condition that causes the loss of hair over the entire scalp; Alopecia universalis is when the condition of hair loss spreads over the entire body, even including eyebrows and eyelashes.
Although the causes of Alopecia areata are unknown, there is evidence that it could be a breakdown of the immune system resulting in what is called an autoimmune disorder. This is when the immune system thinks that the hair follicle is a foreign body, and attacks it. There is also the possibility that heredity plays a factor, because studies have shown that for one out of five people with alopecia areata, someone else in the family also had it. Ongoing research will help to discover the causes of alopecia areata, so that better treatments can be used.
Androgenetic Alopecia is the modern medical term for either male or female pattern baldness. Androgenetic Alopecia represents close to 95% of all hair loss. This type of hair loss can be defined in two parts. First, andro- means to consist of androgens which are various hormones that control the appearance and development of masculine characteristics such as testosterone. Second is genetics, or the inheritance of genes from either the mother or father. Age added to genetics creates a time clock that signals the hair follicle to produce an enzyme named 5-alpha reductase. When testosterone is present in the follicle and it combines with the enzyme 5-alpha reductase, it produces DHT. DHT attacks the hair follicle, causing it to shrink, finally causing the hair to fall out and not grow back.
Anagen effluvium is the condition where hair loss is caused by internally taking certain medicines that can poison the hair follicle, keeping it from growing. One of the most common medicines that cause this type of hair loss is chemotherapy agents.