Obsessive compulsive disorder (OCD) was very rare up until about the same time anorexia nervosa starting being diagnosed in large numbers. OCD is a disorder where worries, doubts, or superstitious beliefs become so excessive that they severely impact a person's ability to function normally in society. Compulsions such as hours of hand washing or driving around and around the block to check that an accident didn't occur are typical of the disorder. In OCD, it is as though the brain gets stuck on a particular thought or urge and just can't let go.
Typical obsessions are often accompanied with compulsions and may include fear of contamination (compulsion- hand washing), religious or moral doubt (compulsion - counting), fear of losing control of agressive urges (compulsion - checking), excessive guilt (compulsion - praying), etc. Now worries, doubts and superstitious beliefs are all common in everyday life. However, with OCD these thoughts become excessive.
Much of the literature on anorexia nervosa sites obsessive compulsive disorder as being a precipitating factor in developing an eating disorder. Many therapists interpret excessive exercise as a compulsion induced by the obsession with body image or weight loss. Some of the strange eating habits (like eating one pea at a time, or pushing food around on the plate) are also interpreted as rituals or compulsions.
The diagnosing of this disorder seems to be exploding in western countries. Again, public awareness has played a key role in this. This is a familiar pattern with modern psychology. What were essentially rare and unheard-of disorders reach almost epidemic proportions in just a few years after some best-selling book, documentary, or talk show focuses on the subject. Because of the explosion in the number of cases, it is generally assumed that these disorders were kept secret before, and went mainly undiagnosed.
Typically, researchers try to determine the prevalence of these disorders by exptrapolating surveys done on a small sample population. From these surveys, estimates are made of the number of people afflicted with the disorder nationwide. In one study, over 5,000 students in high schools filled out a questionaire about disturbing habits or thoughts, and from this number approximately 20 severe cases of OCD were discovered. The rate of 1 in 250 was exptrapolated to one million adolescents nationwide, and since there are three adults for every child who has the disease, it was estimated that 4 million people have the disorder in the United States alone.
It should be made clear that determining the prevalence of OCD or any other psychiatric disorder using surveys or questionnaires is simply bad science. Correctly diagnosing psychiatric disorders requires an experienced psychiatrist to perform a detailed investigation of the patient's history, hours of interviewing both patient and intimate friends, and of course diagnostic testing to rule out medical illness. Even then the possibilty of misdiagnosis is significant, since the diagnostic criteria for most psychiatric disorders are fairly subjective. Being human, therapists can also be quite fallible, and may have difficulty recognizing their own biases and how theses biases affect their interpretation of behavior and phenomenon.
Take for example our daughter's case. Originally diagnosed with AN, an abdominal ultrasound reveals the true source of the eating difficulties, being gallstones. She has many of the classic symptoms of gallbladder disease. A team of eaitng disorder experts from one of Canada's top pediatric hospitals cannot arrive at a firm diagnosis despite hours of interviews. So don't ever think that the prevalence of Anorexia Nervosa, Obsessive Compulsive Disorder, or any other psychiatric disorder can be determined by exptrapolating survey or questionnaire results. The interpretation of these survey results is far too subjective to be of any scientific significance.