Acne epidemiology and pathophysiology.

The demographic profile of facial acne vulgaris has changed during the past several decades; 12 years of age is no longer the low end of the "normal" range for onset of acne. The available epidemiologic evidence raises more questions than it answers regarding the etiology of this downward shift. More study is needed to clarify whether the trend toward an earlier onset of puberty in the United States has influenced the clinical picture of acne. Additional research will help advance understanding of the spectrum of pathophysiologic changes in acne in younger pediatric patients and whether it varies from that found in individuals in whom the onset of acne occurs at approximately 12 years of age or later.