Symptom dimensions in obsessive-compulsive disorder: from normal cognitive intrusions to clinical obsessions.

Cognitive behavioral models of obsessive-compulsive disorder (OCD) assume continuity between normal obsessional intrusive thoughts (OITs) and obsessions. However, this assumption has recently been criticized. This article examines this issue using a new instrument (the Obsessional Intrusive Thoughts Inventory, INPIOS) specifically designed to assess the frequency and content of 48 OITs, which was completed by 734 community subjects and 55 OCD patients. Confirmatory factor analysis suggests six first-order factors included in two second-order factors, one containing aggressive, sexual, religious, immoral and repugnant OITs, and the other containing contamination, doubts and checking, symmetry and order, and superstition OITs. This structure integrates the research on OC symptoms and OITs. The INPIOS showed excellent known-groups validity, and it adequately represented obsessions as well as OITs. OCD and community subjects experience OITs representative of all types of obsessional contents. The dimensional structure is discussed in terms of OIT/obsessive-compulsive symptom structures currently proposed.