Common scalp conditions

Male pattern baldness results from sensitivity to the effects of dihydrotestosterone (DHT) in some areas of the scalp. It is an inherited, genetically determined problem in which the DHT shortens the anagen (growth) phase of the hair cycle, reducing the normal cycle of three to six years to a few weeks or months. At any one time, 90 per cent of the scalp hairs are in the anagen phase; the hair follicles produce fewer and finer such hairs, resulting in thinning of the hair and alopecia.

Up to 50 per cent of men are affected, and the numbers increase with age. A receding hairline first occurs before extending to the top and front of the head. It does occur in women, particularly after the menopause but it is less common and tends to cause a gradual thinning of the hair rather than actual baldness.