Androgenetic alopecia
Androgenetic alopecia is a common form of hair loss in both men and women, characterized by distinct patterns of thinning and receding hairlines.
Overview
Androgenetic alopecia is a common form of hair loss. In men, it is also known as male pattern baldness, and in women, it is also known as female pattern hair loss.
Symptoms
In Men
- Hair loss begins above both temples.
- The hairline recedes over time to form a characteristic "M" shape.
- Hair thins at the top of the head (vertex or crown).
- Often progresses to partial or complete baldness.
In Women
- Hair becomes thinner at the top of the head.
- The middle part widens.
- The hairline does not typically recede.
- Rarely leads to total baldness.
Causes & Risk Factors
A variety of genetic and environmental factors play a role in androgenetic alopecia. Research indicates that this form of hair loss, particularly in men, is related to hormones called androgens, specifically dihydrotestosterone (DHT).
Androgens regulate the hair growth cycle. Too much stimulation of hair follicles by androgens can lead to a shorter growth period, resulting in shorter and thinner strands of hair. The growth of new hair to replace shed strands is also delayed.
Genetic variations in the AR gene are involved in this condition. This gene provides instructions for making the androgen receptor, which allows the body to respond to DHT and other androgens. Variations in the AR gene may result in receptors that are more easily stimulated, leading to increased activity in hair follicles.
Associated Conditions
- In Men: Coronary heart disease, prostate enlargement, prostate cancer, insulin resistance disorders (diabetes and obesity), and high blood pressure (hypertension).
- In Women: Increased risk of polycystic ovary syndrome (PCOS), which can lead to irregular menstruation, acne, hirsutism (excess body hair), and weight gain.
Frequency
Androgenetic alopecia affects an estimated 50 million men and 30 million women in the United States. While it can start as early as the teens, the risk increases with age; more than 50 percent of men over age 50 have some degree of hair loss. In women, hair loss is most likely after menopause.