its treatment include the formation of pyogenic granulomas, osteoma cutis, and acne with facial edema. Early and aggressive treatment of acne is advocated by some in the medical community to reduce the chances of these poor outcomes. Mental health impact There is good evidence to support the idea that acne and associated scarring negatively affect a person's psychological state, worsen mood, lower self-esteem, and are associated with a higher risk of anxiety disorders, depression, and suicidal thoughts. Misperceptions about acne's causative and aggravating factors are common, and people with acne often blame themselves, and others often blame those with acne for their condition. Such blame can worsen the affected person's sense of self-esteem. Until the 20th century, even among dermatologists, the list of causes was believed to include excessive sexual thoughts and masturbation. Dermatology's association with sexually transmitted infections, especially syphilis, contributed to the stigma. Another psychological complication of acne vulgaris is acne excoriée, which occurs when a person persistently picks and scratches pimples, irrespective of the severity of their acne. This can lead to significant scarring, changes in the affected person's skin pigmentation, and a cyclic worsening of the affected person's anxiety about their appearance. Epidemiology Globally, acne affects approximately 650 million people, or about 9.4% of the population, as of 2010. It affects nearly 90% of people in Western societies during their teenage years, but can occur before adolescence and may persist into adulthood. While acne that first develops between the ages of 21 and 25 is uncommon, it affects 54% of women and 40% of men older than 25 years of age and has a lifetime prevalence of 85%. About 20% of those affected have moderate or severe cases. It is slightly more common in females than males (9.8% versus 9.0%). In those over 40 years old, 1% of males and 5% of females still have problems. Rates appear to be lower in rural societies. While some research has found it affects people of all ethnic groups, acne may not occur in the non-Westernized peoples of Papua New Guinea and Paraguay. Acne affects 40–50 million people in the United States (16%) and approximately 3–5 million in Australia (23%). Severe acne tends to be more common in people of Caucasian or Amerindian descent than in people of African descent. History Historical records indicate Pharaohs had acne, which may be the earliest known reference to the disease. Sulfur's usefulness