The Hair Growth Cycle

Hair is composed of proteins (keratins) that are anchored and grow out from a hair follicle. The hair on the scalp grows at a rate of about one-half inch a month, but growth slows with age. The average scalp contains about 100,000 hairs.

Hair goes through a natural growth cycle of three stages. The anagen phase is the period of active growth, lasting for two to eight years. At any time, about 90 percent of scalp hairs are in this growth phase. The next phase is the catagen phase, characterized by shrinking and degradation of the hair follicle. This lasts for about two to four weeks. The final phase in the telogen stage, a resting period lasting about three months. During the telogen phase, the follicle that anchors the hair is totally degraded and the strand of hair can easily fall out or be pulled out. Most hair is shed during the telogen phase.

Hair Loss in Women

An average person loses about 50 to 100 telogen hairs every day. But as men and women get older, they may experience a hereditary form of hair loss, called androgenetic alopecia, or pattern baldness. Researchers estimate 21 million women in the U.S. have some degree of female pattern baldness. The condition affects about 38 percent of women by 70.

In men, pattern baldness is characterized by a receding hairline and loss of hair on the top of the scalp. Women with pattern baldness are more likely to keep their hairline and have widespread thinning of the hair. In some women, the hair loss is more noticeable on the back of the scalp while in others it’s more visible in the front.

Getting to the “Root” of Hair Loss in Women

In men, pattern baldness is typically related to genetics and hormone changes. The cause in women is less clear. Researchers with the Sadick Dermatology Research Group in New York City recently performed skin biopsies from the scalps of women with pattern baldness. They found that many of the women had developed antibodies in the hair follicle. Dermatologist, Neil Sadick, M.D., says these findings suggest there is some type of inflammatory process causing the body’s immune system to attack the hair follicle, leading to premature destruction of the follicle and hair loss. He identifies the problem as a new subset of hair loss and calls it, low-grade autoimmune hair loss. Sadick adds that many women with pattern baldness report having a “burning” scalp sensation before the loss of their hair, which supports the theory of an autoimmune attack on the hair follicle.

Since inflammation may be a key factor in female pattern baldness, treatment with anti-inflammatory medications may slow or stop the process. One therapy he recommends is a topical steroid, called flucinonide. When applied to the skin, the lotion reduces itching, redness and other signs of inflammation. Other treatments that may be used include 2% topical minoxidil (Rogaine®) and an LED red light source that stimulates blood flow to the scalp and enhances hair growth.

Sadick will present his findings in the summer at the International Society of Hair Restoration Surgery held in Amsterdam on July 22-26.

For general information on hair loss: American Academy of DermatologyInternational Society of Hair Restoration Surgery