Male-pattern baldness (MPB) or its medical reference – androgenetic alopecia, is the most common type of hair loss, affecting around half of all men by fifty years of age. It usually starts around the late twenties or early thirties and most men have some degree of hair loss by their late thirties.
It generally follows a pattern of a receding hairline, followed by thinning of the hair on the crown and temples, leaving a horseshoe shape around the back and sides of the head. There are various degrees of MPB that are measured using the Norwood Hamilton Scale. These range from a Norwood 1 (NW1) where no hair loss is experienced, through to Norwood 7 (NW7) which means total loss of all hair on top of the head, with or without the ‘horseshoe’ ring of hair at the back and sides.
A number of factors, both psychological and physical, can also lead to hair loss. Stress, depression and anxiety can all cause you to lose your hair prematurely, while physical factors, such as illness or hormonal imbalance can also contribute.
The other common causes of hair loss include:
- Nervous disorders
- Over-styling (women) or tight styles
- Toxic substances
- Injury and impairment
As well as affecting men, baldness can also affect women (female-pattern hair loss). Similar to male-pattern hair loss, both heredity factors and hormones seem to play major roles in female pattern hair loss. However, patterns of hair loss appear differently in women than in men. Women with androgenetic alopecia more often have diffuse thinning on all areas of the scalp.
For women the extent of hair loss is shown on the Savin Scale, which measures overall thinning as well as the density of the hair, as illustrated in the diagram below. In addition, as a result of styling methods and fashionable extensions, hair loss is becoming an increasing problem for women.