problem. The medical community has established a series of definitions of depression, including the differences between major depressive disorder and other kinds of depression, such as bipolar disorder and the milder dysthymic disorder. However, a diagnosis of any of these disorders remains subject to subjective evaluation. Norman Rosenthal (1998) writes, "For better or for worse, in your recollections of how you have been feeling and your accurate take on your present mood, you hold the key to determining whether or not you are depressed" (p. 103). A trained clinician can fill in the DSM-IV checklist for a given patient, but the patient's own self-analysis provides the only completely reliable confirmation of the diagnosis.
Accordingly, experts disagree on the extent to which clinical depression affects the population. Russ Colchamiro (1998, January), writing in American Druggist, quotes the National Institute of Health as saying that depression affects 17 million adult Americans (p. 28). None of the other publications cite this figure; the closest agreement comes from Rosenthal (1998), who writes, "Depression . . . is estimated to affect 17.6 million people in the United States and to cost the country 43 billion dollars each year" (p. xiv). Klaus Linde and his colleagues (1996, August 3) contend that the estimated lifetime prevalence of depression in the United States is 17 percent (p. 253), while two years later John S. Markowitz (1998, September 7) puts the figure for all mood disorders at just 8.3 percent (p. 50), still a significant number but also a serious discrepancy. Christopher Hobbs (1997) writes, "Clinical depression affects over fifteen percent of the population. In the United States, this means that over 40 million people will experience clinical depression and associated symptoms such as anxiety and insomnia" (p. 13).
Researchers have attempted to focus on the causes of depression, and many clinicians b...