Acne is a disorder of the sebaceous glands that usually presents during the teenage years. Onset at this time is due to hormonal changes that occur during puberty--specifically elevations in the androgenic hormone testosterone.
Puberty and Hormones
The two major sex hormones are estrogen and testosterone. Changes in the relative levels of these hormones during puberty cause acne. Usually, the higher the adolescent's testosterone levels in relation to estrogen levels, the more likely she'll develop acne. Estrogen is classified as an estrogenic hormone and causes feminization; conversely, testosterone is an androgenic hormone and causes masculinization. Manifestations of masculinization are development of facial, pubic and axillary (armpit) hair, deepening of the voice, muscle thickening, enlargement of the testicles and penis, weight gain, body growth and possible acne. Because pubescent males experience greater increases in testosterone than females of the same age, they are more likely to suffer from acne and their acne is usually more severe.
The Pilosebaceous Unit and Acne
The pilosebaceous unit is made up of the hair follicle and the sebaceous gland. The sebaceous gland is located at the base of the pilosebaceous unit (PSU) and produces an oily substance called sebum that provides skin lubrication. Sebum travels up the length of the PSU and is released through the unit's opening onto the skin.
The Acne Cascade
Acne lesions develop because of the following testosterone-induced, three-step cascade of events: First, the PSU becomes inflamed due to an inflammatory response. This inflammation leads to gland swelling and increased production of skin cells called keratinocytes. Second, the swelling of the gland results in a reduction of the diameter of the gland. This, combined with the increased number of keratinocytes and other debris, results in the gland becoming plugged and accordingly unable to release the sebum produced by the gland. Third, the blocked gland becomes infected by a type of bacteria named Propionobacterium acne. The resultant blocked, inflamed and infected glands reveal themselves as the red, irritated lesions of acne. The lesions known as whiteheads or blackheads are due to the combination of debris, inflammation and infection.
What Does and Does Not Cause Acne
Factors that contribute to the development of acne include activities that can block skin glands such as thick makeup, oily lotions and creams, and applying hands to the face. Another known major factor is emotional stress, a common adolescent concern. Contrary to popular mythology, there are no foods that are known to contribute to the development of acne.
Time Course of Acne
Because acne is a hormonally mediated medical condition, it tends to resolve when the causative hormone imbalance resolves. Whereas the onset of puberty is caused by testosterone increase, resolution of puberty is caused by the return of testosterone to normal levels. As a general rule, the end of puberty brings with it the much-awaited end of acne as well.
References
- "Color Atlas and Synopsis of Clinical Dermatology;" Thomas B. Fitzpatrick, MD, PhD, DSc, Machiel K. Polano, MD, Dick Suurmond, MD, Richard Allen Johnson, MDCM; 1989
- "Harrison's Principles of Internal Medicine;" Jean D. Wilson, MD, Eugene Braunwald, AB, MD, Kurt J Isselbacher, AB, MD, Robert G Petersdorf, AB, MD, Joseph B Martin, MD, PhD, Authony S Fauci, MD, Richard K. Root, MD; 1991
