According to the National Institutes of Mental Health, major depression is one of the most common mental disorders in the United States, affecting over seventeen million Americans. This is a serious public health issue because depression can severely impair a person’s ability to carry out major life activities. The prevalence of depression is nearly twice as high in females as it is in males, and the rate of depression is highest among young people aged 18–25. An estimated 65 percent of people who have been diagnosed with depression are treated with a combination of psychotherapy and medication, with mixed success (www.nimh.nih.gov).

Dr. X has noticed that patients in his practice who are depressed also have lower levels of a certain chemical in their blood. He develops a product that raises the level of that chemical, and sure enough his patients claim they feel much better. On the basis of this, he writes a book touting the importance of boosting levels of that chemical, goes on talk shows, and launches a self-help website in which he offers his product for sale.