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Causes of Acne

70% to 80% of young adults are affected by acne, a common skin disorder affecting the face, neck, chest, and back. Though not physically disabling, this skin disease can cause severe emotional stress due to permanent facial scarring and due to its persistence. It usually occurs during difficult period of growing up and development of a young adult. Appropriate treatment is needed to dramatically improve the lives of the affected individuals.

Plugged sebum and keratin lodged in the follicular ducts called comedones are the primary lesions of acne. These are usually non-inflammatory. However, if these comedones rupture the follicular wall, an inflammatory reaction to the sebum produces papules, pustules, and cysts. Propionibacteria, anaerobic bacterium that lives in the microenvironment of hair follicles, also promotes inflammatory lesions. If the immune system detects bacteria in the ruptured hair follicles, it responds and tries to kill them, resulting to inflammatory lesions. These lesions may produce scars if the inflammation is intense enough.

What causes the increased production of sebum and does this lead to acne? Several factors maybe involved in this process.

Androgens

Androgens have been shown in numerous studies to be a major contributory factor in the production of acne. The gonads and the adrenal glands produce most androgens. However, some androgens are also produced locally by the sebaceous glands from the adrenal precursor hormone DHEA.

The interaction of the major androgens like testosterone with the sebaceous glands through androgen receptors is well known. However, the cellular or molecular mechanism by which androgens stimulate sebum production is not yet fully understood. The cells of the basal layer of the sebaceous glands and the outer root sheath, keratinocytes of the hair follicle, contains the androgen receptors.

These five pieces of clinical evidence shows the important role of androgens in stimulating sebum production.

  • The higher serum levels of DHEAS (a precursor of testosterone) in pre-pubertal period causes the development of early acne.
  • The lack of functional androgen receptors in androgen-intensive subjects inhibits sebum production thus prevents acne development.
  • Tumors of the ovary of adrenal gland that produces androgen are also associated with acne.
  • Testosterone and DHEAS administration systematically also increases the size and secretion of sebaceous glands.
  • Higher serum androgen levels often cause severe acne.

Hormones, therefore, are clearly involved in acne development.

Acne Causing Stress

The onset of acne in women coincides with menarche, although its prevalence varies widely. It has also been interestingly identified that women over 25-years of age, some even in their forties, have low grade persistent acne. Stress induced secretion of adrenal androgens is believed to be the cause of this condition. Until recently, emotional stress has been anecdotally linked to acne because objective assessment has been lacking. Studies though, show that there is statistical correlation between stress and acne.

Role of Growth Hormones in Acne Development

Produced by the pituitary gland, growth hormone stimulates growth by acting on the liver and peripheral tissues to stimulate insulin growth factor production (IGF), also known as somatomedians. The more prevalent IGF-1 and also the IGF-2 are the two types of IGF, which is a known promoter of keratinocyte activity, and increased sebaceous gland oil production. Because of this sebaceous gland oil increasing production property, growth hormone may be involved in acne development. During adolescence, the growth hormone secretion and IGF-1 serum levels are at their highest, which explains why acne is also widespread at this age. Production of IGF-1 molecules can also happen locally in the skin where they can interact with the IGF receptors on the sebaceous glands, increasing sebum production. The development of acne in teens may also be contributed to the growth that occurs in them.

Diet Can Cause Acne

Development of acne due to diet has been traditionally dismissed as a myth. However, the observation that acne is almost absent in non-westernized cultures and the presence of acne in western or westernized cultures suggests that diet and the environment could be causes. The high glycemic diet of the West, as suggested by one study, could cause acne by producing hyperinsulinemic states.

Genetic Factors in Acne Development

Facial oiliness or seborrhea is another factor believed to be a pre-conditioned for acne. The genetic make up of a person partly affects the degree of oiliness that an individual experiences. As some genes code for a higher level of sebaceous gland activity and oil production, they may also play a role in the kind of sebum that is produced. Some genes also code for higher levels of the production of cholesterol, a relatively sticky substance. Cholesterol produced by the sebaceous glands serves as the binding agent of the oils and the dead cells in the hair follicle canal, which forms the nucleus of the sebum plug.