๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
EPIDEMIOLOGY
Acne vulgaris affects ~40โ50 million individuals each year in the US alone, leading to an estimated annual cost in the US of at least $2.5 billion. Globally, acne accounts for ~0.3% of the total and ~15% of the dermatologic disease burden. With a peak incidence during adolescence, acne affects ~85% of young people between 12 and 24 years of age and is therefore a physiologic occurrence in this group. With the general trend over the past few decades for an earlier onset of puberty, preadolescent acne affecting children 7 to 11 years of age has also become more common. While typically thought of as a disease of youth, acne often continues to be problematic well into adulthood. In a survey-based study in the US, 35% of women and 20% of men reported having acne in their 30โs, while 26% of women and 12% of men were still affected in their 40s7. White boys and men have a tendency to have more severe nodulocystic disease than other groups.
Individuals at increased risk for the development of acne include those with an XYY karyotype or endocrine disorders such as polycystic ovarian syndrome, hyperandrogenism, hypercortisolism, and precocious puberty. Patients with these conditions tend to have more severe acne that is less responsive to standard therapy.
Genetic Factors
The precise role of genetic predisposition in the multifactorial pathogenesis of acne remains to be determined. The number, size, and activity of sebaceous glands is inherited. In addition, the concordance rate for the prevalence and severity of acne among identical twins is extremely high. It is widely believed that the tendency to have substantial acne (including the nodulocystic variant) runs in families, and an association between moderate-to-severe acne and a family history of acne has been observed in several studies. Genes found to have a possible link to acne via genome-wide association studies (GWAS) and other methods include those encoding components of the tumor transforming growth factor-ฮฒ (TGF-ฮฒ) pathway, other inflammatory mediators, and regulators of androgen metabolism.
Dietary Factors
The relationship between diet and acne remains controversial. Several observational studies in different ethnic groups have found that the intake of milk, especially skim milk, is positively associated with acne prevalence and severity. Exacerbation of acne with the use of whey protein supplements for bodybuilding has also been reported. Vitamin B supplementation can potentially trigger the development of acne or an acneiform eruption by altering the transcriptome of skin microbiota, leading to increased production of proinflammatory porphyrins by Cutibacterium acnes.