Science of Hair Loss
Scalp hair is a complex topic full of cultural and psychosocial implications. Scalp hair is one of our most defining characteristics. Even a bad hair day can cause social and emotional trauma and negatively impact self-esteem and our perception of our beauty. Hair loss can have a significant impact on quality of life. Men and women alike can suffer embarrassment, depression, and altered self-image and affect social activities. About half of African-American women suffer from hair loss.
Science has revealed that we are born with all the hair follicles we will ever develop, about 5 million. Hair follicles continually interact biologically with the rest of the body. Biological signals tell the follicles when to cycle. Follicle activity and hair production depend in part on hormone control.
Hair grows from the root in the follicle. The root is made of live protein cells which are nourished by tiny blood vessels in the scalp, and create cells that grow hair. An outer sheath protects the growing hair. As the hair grows it passes the oil gland at the base of the hair shaft, which conditions the hair and skin. By the time the hair is visible, it has died.
Hair Growth Cycles:
Hair grows very fast and male hair grows faster than female hair. Hair cycles are continuous during the life of a hair follicle, and a complete cycle lasts over 2-8 years.
The 3 stages of growth and shedding.
- Anagen phase (growth) This is the active phase of scalp hair where cells in the root are creating new hair, which pushes the old hair out of the scalp. Science has shown that people who have trouble growing hair beyond a certain length have a shorter active growth phase, while people with long hair have a longer active growth phase. When we lose our hair in old age it is thought to be related to aging hair follicles.
- Catagen phase- (dormant) is when the hair is dormant and lasts about 2-3 weeks. About 3% of all hairs are in the catagen phase at any one time.
- Telogen phase (Rest)- is the resting phase of hair follicles. About 6-9% of all hairs are in this phase at any given time. It lasts about 100 days.
Scalp hair grows about 6 inches a year. Growth and shedding are random in humans, and the average healthy person will shed 50-100 dead hairs per day.
Studies show that multi-potent stem cells are present in the hair follicles, and remain in a quiet state until they receive signals from the environment that it is time to grow new hair. A gene is required to grow hair and when it is missing, hair grows in shorter intervals. Your genetic heritage will determine whether you suffer from male or female pattern baldness.
Hormones and hair growth
Androgens or male hormones are the key to hair growth in men and women. Combined with thyroid hormones and female hormones, they stimulate hair to grow. Scalp hair follicles are not dependent on male hormones for growth but testosterone plays a role in permanent scalp hair loss known as androgenic alopecia, also called male pattern baldness and female pattern baldness. Here scalp hair follicles metabolize testosterone which causes the follicles to stop hair growth.
Hyperandrogenism is a medical condition caused by excessive male hormones and is often caused by polycystic ovary syndrome.
Forms of Hair Loss
Hair loss is most commonly due to heredity. It can also result from immune system dysfunction, drugs and treatments like chemotherapy, and traction or pulling on the hair due to hair styles.
Androgenetic alopecia affects men and women and is based on your genetics. It is the most common cause of hair loss in men and women. Male pattern baldness takes a common pattern and onset often occurs in the 30s, while female pattern baldness is more diffuse- thinning hair all over the scalp and often occurs in the 40-50 age range. There are numerous successful treatments available.
Alopecia Areata is hair loss caused by immune system dysfunction. It may appear as patchy balding or total balding and may appear quickly, and requires medical treatment.
Telogen effluvium is another common form of hair loss. It results as a response to stress, surgery, childbirth, gastric bypass surgery, iron deficiency, and chronic thyroid disease. This is an increase in the amount of hair in the telogen phase, above the normal 6-9%.
Hair loss can also result from an underlying disease involving the endocrine system, the digestive system, urinary system and the skin.
Dr. M. David Cole, M.D. at Horizon Dermatology and Laser Institute in Newport Beach, Torrance, and Fullerton, California, is an expert in hair loss, and it treatments. He understands that hair loss is a frustrating condition and he specializes in hair restoration solutions for men and women. As a board-certified dermatologist, his goal is to help you look and feel your best. He knows that looking better will make you feel better. Let us help you achieve and maintain healthy, beautiful hair.
Dr. M. David Cole, MD is a fellow of the American Academy of Dermatology and previously trained hundreds of physicians in facial cosmetic procedures and aesthetic dermatology at UC Irvine School of Medicine. He is revered for this outstanding aesthetic results.