Intrusions and Inferences in Obsessive Compulsive Disorder

This article compares two models about the nature of obsessional intrusions: one, that they are just ‘normal thoughts’ whose obsessional significance derives from their appraisal; the other, that they are specific inferences about thoughts and things, which form conditional premises and are part of the obsessional reasoning. Support for the first model comes from questionnaire studies showing that the content of obsessional intrusions is similar or even identical to intrusions in non-obsessional people. Also there is growing clinical evidence that addressing the appraisals made about the intrusions rather than the content of the intrusions alleviates OCD symptoms. However, regarding the second model, intrusions tend to be thematic; they do explicitly take the form of an ‘inference’ (X may occur) whose development can be traced to inductive logic; ‘intrusions’ can be modified by changing inference processes, and such modification alone can reduce OCD-related anxiety. It is proposed that both primary inference and secondary appraisal may form two separate parts of the same evaluative sequence, and both should be targeted in treatment.P Copyright  2002 John Wiley & Sons, Ltd.