Much of the confusion in the professional and lay literature regarding the differences between OCD and other conditions stems from the many different uses of the words obsession and compulsion. To be true symptoms of OCD, obsessions and compulsions are strictly defined as described earlier in this article. A key point to remember is that the compulsions of OCD are not considered inherently pleasurable: at best, they relieve anxiety.

As a contrasting clinical example, although patients seeking treatment for “compulsive” eating, gambling or masturbating may feel unable to control behaviors they acknowledge as deleterious, at some time in the past, these acts were experienced as gratifying. By the same token, sexual “obsessions” are relabeled as preoccupations when it is evident that the person either derives some sexual satisfaction from these thoughts or the object of these thoughts is coveted. A woman who says she’s “obsessed” with an ex-boyfriend even though she knows she should let him alone is probably not suffering from OCD. Here the diagnostic possibilities would include erotomania (as depicted in the movie “Fatal Attraction”), pathological jealousy and unrequited love.

The presence of insight distinguishes OCD from a psychotic illness, such as schizophrenia (although some people with schizophrenia also have obsessive-compulsive symptoms). Patients with psychosis actually lose touch with reality and their perceptions may become distorted. Obsessions may involve unrealistic fears, but unlike delusions, they are not fixed, unshakeable false beliefs. The symptoms of OCD may be bizarre, but the patient recognizes their absurdity. A 38-year-old computer specialist told me that his worst fear was losing or inadvertently throwing out his five-year-old daughter. He would check inside envelopes before mailing them to ensure she was not inside. While freely acknowledging this impossibility, he was so tormented by pathological doubt that his anxiety would escalate uncontrollably unless he checked. Occasionally, an obsession can be misdiagnosed as an auditory hallucination when the patient, especially a child, refers to it as “the voice in my head” even though itÆs recognized as his/her own thoughts.

Distinguishing between certain complex motor tics and certain compulsions (e.g., repetitive touching) can be a problem. By convention, tics are distinguished from “tic-like” compulsions (e.g., compulsive touching or blinking) based on whether the patient attaches a purpose or meaning to the behavior. For example, if a patient feels an urge to repeatedly touch an object, this would be classified as a compulsion only if it was preceded by a need to neutralize an unwanted thought or image; otherwise it would be labeled a complex motor tic. Tics are often identified by “the company that they keep”: if a complex motor act is accompanied by clear-cut tics (e.g., head jerks), it is most likely a tic itself.