There is no reliable diagnostic test for obsessive-compulsive disorder (OCD). The diagnosis is usually based on a thorough face-to-face interview conducted by an experienced mental health professional. Perhaps someday, as we learn more about the underlying biology of OCD, there will be genetic markers or characteristic patterns on brain scans that will confirm diagnosis. But we are not there yet. On the other hand, obtaining some medical tests may be appropriate to rule out neurological conditions that may produce obsessive-compulsive symptoms.

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For example, consider a person who shows symptoms of OCD for the first time after a head injury at the age of 45. It would be reasonable to explore the possibility that an acute injury to the brain might have caused the symptoms of OCD. Another example is a 10-year-old girl who suddenly develops concerns about germs and begins washing her hands incessantly. She also displays jerking movements of her arms. These symptoms appear one month after having had a suspected strep throat.

Although such onset is not typical of OCD, there is reason to believe that some cases may be precipitated by an abnormal reaction of the immune system to an untreated upper respiratory infection. Sue Swedo, MD, of the National Institute of Mental Health has coined the term PANDAS to refer to this variety of OCD. Most cases of OCD begin inconspicuously and gradually become more apparent over many months or years. It is only in retrospect that one looks back and recognizes some of the early signs of the illness.

Nevertheless, there are some things you can do to determine if you have OCD. In fact, the majority of individuals who are diagnosed as having OCD first make the diagnosis themselves. The process of discovering OCD often starts with watching a TV talk show or news segment, or reading a newspaper, magazine or internet article, like you are doing right now. Awareness about OCD grew following a 1987 segment on OCD broadcast by the ABC-TV network program “20/20.” That coverage triggered a cascade of media attention on OCD that stimulated clinical and research activity and galvanized an advocacy movement — culminating in the formation of the Obsessive Compulsive Foundation, Inc.

Many people with OCD felt alone until they witnessed the story of someone like themselves. They thought they were losing their mind until they realized they were suffering from a legitimate brain-based illness. They didn’t know how to describe their experience until they heard it described by someone else who gave it a name. They finally had hope because scientists were making progress in squelching this unwelcome ruler of their inner domain.

It often takes people a long time to seek out help for OCD, even after they learn it is a treatable illness. Individuals may call years after viewing an OCD story on Oprah or “20/20” to ask for a consultation. When asked why it took so long, the reason given is usually embarrassment. The symptoms of OCD can be so disagreeable and so private that they are very difficult to share with anyone, including loved ones and trained professionals. A simple device used to reduce the shame of sharing such sensitive material is a checklist featuring examples of obsessive-compulsive behavior. Although it is best to do this in person, some people prefer to fill out a questionnaire initially on their own.

Sometimes the examples seem absurd and one can’t imagine how anyone in her right mind could have such thoughts or engage in such ludicrous behaviors. Other times, the questions are right on target and it feels like the checklist was written just for the individual completing it.

To experienced clinicians, none of the thoughts or behaviors of OCD seem odd or outlandish. They are products of the disorder, the “hiccups of the brain” as Judith Rapoport, MD, once called them. The symptoms of OCD don’t influence a clinician’s perception of the person so afflicted any more than pus from an infected wound would make a physician feel that the patient is morally decayed.