The Extent of Mental Illness

Since the 1920s, social scientists have tried to ascertain the extent of mental illness. These researchers essentially have adopted medical definitions of mental illness (which, as we will see later in this chapter, are problematic). However, whereas doctors and other clinicians have focused on how biological or psychological factors can foster mental illness, social scientists have focused on how social factors can do so.

Over the years, researchers using a variety of methods have reached two consistent conclusions regarding the extent of mental illness. First, all societies, from simple to complex, include individuals who behave in ways considered unacceptable and incomprehensible. Second, symptoms of mental disorder are fairly common. According to the National Comorbidity Survey Rep- lication, as of 2018 the largest national survey on the topic based on a random sample; during the course of one year, approximately 31% of working-age adults experience a diagnosable mental illness, with 20% expe- riencing a moderate or severe disorder. The most common illnesses are major depression and problems with alcohol use, which were reported by 17% and 13%, respectively. These estimates, however, are probably high because they are based on reports of symptoms taken out of context. When an individual reports that he is extremely sad, survey researchers can’t tell whether the sadness was caused by clinical depression or financial problems. Nor can re- searchers tell whether a woman who reports losing weight has done so because of depression or because she wanted to fit into her wedding dress.