What is worse than pimples? Lots of things, I'm sure, but acne is so common and so unpleasant that it warrants its own article. Especially as spring and summer approach, we tend to want to wear less makeup and be outdoors more in the bright unforgiving sun, which can be embarrassing with a face full of blemishes.So here is a synopsis of what causes acne, to the extent that we currently understand it. Information has been compiled from a variety of sources, including journal articles, the American Academy of Dermatology website, and online articles written by dermatologists. There's so much information out there about acne, and so many products claiming to treat it, that sorting things out and choosing a course of treatment can be confusing and overwhelming. This is my effort to clarify and simplify the morass.
1. How Skin Works
The basic unit of skin, for our purposes, is made up of a sebaceous gland, a vellus hair, and a duct, or pore, leading from the deeper layer of skin to the surface. The sebaceous gland produces sebum (oil) and delivers it to the skin's surface, keeping skin moisturized and potentially providing protection against invaders. Skin cells continually die, slough off, and regenerate.
2. What is Different about Acne-Prone Skin?
In general, 3 things happen differently with acne-prone skin.
First, more sebum than usual is produced. People with acne often have oily skin, and I'll explain why this is problematic in a moment. There is also some evidence that the sebum produced by acneic skin is "stickier" than normal sebum and therefore more likely to trap dead skin cells. Which leads to...
Second, the dead skin cells of people with acne do not slough off neatly, but rather remain stuck in the excess sebum near the skin's surface or deeper inside the pore. This is called "retention hyperkeratosis." This skin cell buildup creates a blockage that traps sebum in the pore. As the sebum builds up, the pore becomes enlarged and/or inflamed, and...
Third, the skin's normal bacteria grow and replicate abnormally well in the trapped sebum. Propionibacterium acnes, or P. acnes, is the name of this bacteria, and it grows well in anaerobic conditions (environments with little oxygen). The inside of a clogged pore is the perfect breeding ground, so the P. acnes goes wild. Interestingly, P. acnes is not the cause of acne on it's own, but rather a normal bacterium that lives in/on everyone's skin. The overgrowth of this bacteria is the problem, not the presence of the bacteria itself.
This proliferation of bacteria incites an immune response, which leads to inflammation of the clogged pore as the immune cells try to kill the bacteria. This inflammation leads to the redness and swelling often associated with blemishes. Significant inflammation can also result in scar tissue, leaving a lasting mark after the blemish has healed.
3. What Causes the Differences in Acneic Skin's Behavior?
This part is not terribly well-understood. A variety of factors have been identified as contributing to the changes:
First is hormones. Sebum production seems to be influenced most heavily by androgen hormones such as testosterone. Both men and women produce testosterone, which is metabolized in the skin to a more active form of the hormone. This metabolite stimulates oil production and hair growth.
Among adult women with acne, testosterone can play a role if:
(a) Testosterone levels are abnormally high due to an adrenal tumor (rare!) or imbalances of the reproductive system such as polycystic ovarian syndrome (PCOS). These instances are pretty rare and are typically associated with additional symptoms besides acne;
(b) Testosterone levels are normal but a decrease in estrogen allows more expression of testosterone's effects. Estrogen levels decline as we age. This is most often mentioned in the context of menopause, but I believe that estrogen levels decrease gradually throughout adulthood, so it may be that you have more facial hair/acne at 30 than you did at 20. Every woman is different.
(c) Or finally, most commonly, testosterone levels are normal but your skin is very sensitive to the effects of testosterone.
Progesterone can also play a role in acne, especially premenstrual breakouts, by causing the skin to swell slightly and therefore making pores more susceptible to blockage.
There's probably much more to the hormonal aspect of adult acne than we currently know. It is possible that hormones also contribute to the skin's inflammatory response or other aspects of the acne process. Further research will be needed to clarify this area.
A second contributor may be diet, after all. For years, dermatologists vehemently debunked the idea, popular in the 1970's, that junk food promoted acne. Now a recent study from Colorado State University has brought us back around to considering the role of diet in acne. Study results suggested that some people eating a high-glycemic-index (GI) diet are more prone to suffer from acne than those eating a low-GI diet. Basically, glycemic index refers to how rapidly a food is converted into glucose ("blood sugar;" the cells' basic unit of energy) in the body.
Refined carbohydrates like sugar, corn syrup, most flours, chips, pretzels, and refined grains of all types tend to have high glycemic indices, and are converted very rapidly to glucose. This rapid surge of glucose in the blood prompts the release of insulin, responsible for storing away the extra glucose in muscle or fat tissue. Chronic or impaired insulin reactivity is associated with androgen (testosterone) activity in women, though the nature of the relationship is not completely understood. In any case, it appears that eating a diet high in refined carbohydrates may contribute to acne. This is highly plausible, when you consider that acne is very rare among people eating traditional diets, but very high among those of us in the West eating highly refined diets. Food for thought.
A third contributor may be genes. The amount of sebum your skin produces, your body's inflammatory response, and your hormonal levels may all be influenced by your genetic inheritance, though your immediate family may not actually suffer from acne. In my family, for example, many people have related skin ailments such as eczema or skin allergies, and these may be related to my acne by an underlying genetic predisposition. Who knows. Remember, though, genes are not destiny. How you care for yourself and your skin can make a big difference.
Next time: Addressing the Contributors to Acne
