Acne vulgaris is an inflammatory disease of the skin, caused by changes in the pilosebaceous units (skin structures consisting of a hair follicle and its associated sebaceous gland). Acne lesions are commonly referred to as pimples, spots or zits.
The condition is common in puberty, especially among Western societies most likely due to a higher genetic predisposition. It is considered an abnormal response to normal levels of the male hormone testosterone. The response for most people diminishes over time and acne thus tends to disappear, or at least decrease, after one reaches their early twenties. There is, however, no way to predict how long it will take for it to disappear entirely, and some individuals will continue to suffer from acne decades later, into their thirties and forties and even beyond. Acne affects a large percentage of humans at some stage in life.
The most common form of acne is known as "acne vulgaris", meaning "common acne." Excessive secretion of oils from the sebaceous glands combines with naturally occurring dead skin cells to block the hair follicles. There also appeares to be in some instances a faulty keritinization process in the skin leading to abnormal shedding of skin lining the pores. Oil secretions build up beneath the blocked pore, providing a perfect environment for the skin bacteria Propionibacterium acnes to multiply uncontrolled. In response, the skin inflames, producing the visible lesion. The face, chest, back, shoulders and upper arms are especially affected.
The typical acne lesions are: comedones, papules, pustules, nodules and inflammatory cysts. These are the more inflamed form of pus-filled or reddish bumps, even boil-like tender swellings. Non-inflamed 'sebaceous cysts', more properly called epidermoid cysts, occur either in association with acne or alone but are not a constant feature. After resolution of acne lesions, prominent unsightly scars may remain.
Aside from scarring, its main effects are psychological, such as reduced self-esteem and depression. Acne usually appears during adolescence, when people already tend to be most socially insecure.
Causes of acne
Exactly why some people get acne and some do not is not fully known. It is known to be partly hereditary. Several factors are known to be linked to acne:
Hormonal activity, such as menstrual cycles and puberty
Stress, through increased output of hormones from the adrenal (stress) glands.
Hyperactive sebaceous glands, secondary to the three hormone sources above.
Accumulation of dead skin cells.
Bacteria in the pores, to which the body becomes 'allergic'.
Skin irritation or scratching of any sort will activate inflammation.
Use of anabolic steroids.
Any medication containing halogens (iodides, chlorides, bromides), lithium, barbiturates, or androgens.
Exposure to high levels of chlorine compounds, particularly chlorinated dioxins, can cause severe, long-lasting acne, known as Chloracne.
Traditionally, attention has focused mostly on hormone-driven over-production of sebum as the main contributing factor of acne. More recently, more attention has been given to narrowing of the follicle channel as a second main contributing factor. Abnormal shedding of the cells lining the follicle, abnormal cell binding ("hyperkeratinization") within the follicle, and water retention in the skin (swelling the skin and so pressing the follicles shut) have all been put forward as important mechanisms. Several hormones have been linked to acne: the male hormones testosterone, dihydrotestosterone (DHT) and dehydroepiandrosterone sulfate (DHEAS), as well as insulin-like growth factor 1 (IGF-I). In addition, acne-prone skin has been shown to be insulin resistant.
Development of acne vulgaris in latter years is uncommon, although this is the age group for Rosacea which may have similar appearances. True acne vulgaris in older adults may be a feature of an underlying condition such as pregnancy and disorders such as polycystic ovary syndrome or the rare Cushing's syndrome.
Misconceptions about causes
There are many misconceptions and rumors about what does and does not cause the condition:
Diet. One flawed study purported that chocolate, french fries, potato chips and sugar, among others, affect acne.A recent review of scientific literature cannot affirm either way.The consensus among health professionals is that acne sufferers should experiment with their diets, and refrain from consuming such fare if they find such food affects the severity of their acne.A recent study, based on a survey of 47,335 women, did find a positive epidemiological association between milk consumption and acne, particularly skimmed.The researchers hypothesize that the association may be caused by hormones (such as bovine IGF-I) present in cow milk; but this has not been definitively shown. Seafood, on the other hand, may contain relatively high levels of iodine, but probably not enough to cause an acne outbreak. Still, people who are prone to acne may want to avoid excessive consumption of foods high in iodine. It has also been suggested that there is a link between a diet high in refined sugars and acne. According to this hypothesis, the startling absence of acne in non-westernized societies could be explained by the low glycemic index of these tribes' diets.Further research is necessary to establish whether a reduced consumption of high-glycemic foods (such as soft drinks, sweets, white bread) can significantly alleviate acne, though consumption of high-glycemic foods should in any case be kept to a minimum, for general health reasons.
Deficient personal hygiene. Acne is not caused by dirt. This misconception probably comes from the fact that acne involves skin infections. In fact, the blockages that cause acne occur deep within the narrow follicle channel, where it is impossible to wash them away. These plugs are formed by the cells and sebum created there by the body. The bacteria involved are the same bacteria that are always present on the skin. Regular cleansing of the skin can reduce, but not prevent, acne for a particular individual and very little variation among individuals is due to hygiene. Anything beyond very gentle cleansing can actually worsen existing lesions and even encourage new ones by damaging or overdrying skin.
Sex. Common myths state that either celibacy or masturbation cause acne and, conversely, that sexual intercourse can cure it. There is absolutely no scientific evidence suggesting that any of these are factual. It is true, though, that anger and stress affect hormone levels and thus bodily oil production. Whether or not any increases in oil production due to stress are enough to cause acne is currently being researched.