What Causes Acne?
There is no single, identifiable cause of acne. Instead, there are a number of different causes of acne, each of which causes acne of a particular clinical type. The process by which acne develops is a bit like a chain reaction. At the end of the chain is the development of spots on the skin of the acne sufferer. An acne spot is the the result of body's inflammatory reaction to the presence of a comedo, a sticky mass of dead skin cells, bacteria and sebum which blocks a hair follicle. It is not known what triggers the body's inflammatory reaction to comedones, which may have lain dormant for months or even years, and causes acne spots to develop. What is known is that the development of comedones is the result of a combination of factors, which together produce conditions within the hair follicle which encourage comedones to form. The factors implicated in the development of comedones are:
- Seborrhoea, the excessive production by the sebaceous glands of sebum, a greasy substances which is discharged onto the skin's surface.
- The failure of dead skin cells shed by the lining of the hair follicles to be carried to the skins surface and disbursed. The dead skin cells accumulate, stick together to form clumps and cause a blockage within the hair follicle.
- The presence of large numbers of bacteria of the type Propionibacterium acne. This bacterium is part of the normal flora of skin, but is present in the hair follicles of acne sufferers in hugely increased numbers.
Causes of Acne
The factors which cause acne are one step further back in the chain from the factors which cause comedones to be produced. It is at this point of the chain that things diverge, so that, for example, the factors which cause acne of the adolescent type are quite different from the factors which cause occupational acne. The specific cause of a particular clinical type of acne is in each case triggering the same processes which encourage the development of comedones. It is just that there are different causes for acne in each of the different clinical acne types.
Causes of Adolescent Acne
The cause of the adolescent clinical type of acne, often referred to erroneously as teenage acne, is hormonal. The hormones which during puberty stimulate the development of secondary sexual characteristics - the adult body form, development of the sexual organs and growth of pubic hair, and in the male the breaking of the voice, - also stimulate the sebaceous glands to start producing sebum. Prepubescent boys and girls have completely inactive sebaceous glands and produce no sebum. During puberty, it is the action of sex hormones, and in particular the male sex hormones known as androgens, which cause the sebaceous glands to start producing sebum. It is the production of sebum, and particularly the excessive production of sebum (seborrhoea), which triggers the comedogenic process and so causes acne of the adolescent clinical type.
Causes of Other Types of Acne
Many of the rarer clinical types of acne - occupational acne, drug-induced acne, cosmetic-induced acne and occlusion acne, have an identifiable cause which is alluded to in the name. The cause of acne in each of these conditions is explained in the section on clinical types of acne. Occuring in neonates and young babies, infantile acne is the only clinical type of acne for which no definite cause has yet been identified.
Causes of Adult Acne
Acne causes refer to the factors which cause a particular clinical type of acne. The system breaks down if one tries to describe the causes of acne in terms not of clinical types, but of distribution types. Talking about the causes of adult acne, or the causes of back acne, is meaningless. Adult acne may be persistent acne of the adolescent type, but it could equally be a type of occupational acne, or drug induced-acne, or occlusion acne. In four different patients, the causes of adult acne and the distribution of the spots on the body might all be completely different. To labour the point somewhat, the cause of adult acne can only be elucidated from a correct clinical diagnosis of the type of acne from which an adult is suffering.
