Further development of YBOCS dimensions in the OCD Collaborative Genetics study: symptoms vs. categories

Area of Science:

• Psychiatry
• Genetics
• Behavioral Science

Background:

• Previous obsessive-compulsive disorder (OCD) research identified symptom subphenotypes using factor analysis of the Yale Brown Obsessive-Compulsive Scale Symptom Checklist (YBOCS-SC).
• Prior analyses relied on symptom categories, not individual symptoms, and rarely examined the familiality of OCD symptom dimensions.

Purpose of the Study:

• To conduct the first exploratory dichotomous factor analysis using individual OCD symptoms.
• To compare individual symptom results with a refined category-level solution.
• To test the familiality of the derived OCD symptom factors.

Main Methods:

• Factor analysis of YBOCS-SC data from 485 adults with lifetime OCD.
• Analysis conducted at both individual item and symptom category levels.
• Familiality assessed using intraclass correlations in 145 affected sibling pairs.

Main Results:

• Both item- and category-level factor analyses yielded highly similar five-factor solutions for OCD symptoms.
• Four of the five factors demonstrated significant sibling associations.
• Hoarding and Taboo Thoughts dimensions exhibited the most robust familiality (r ICC ≥ 0.2).

Conclusions:

• Converging evidence supports a five-factor structural model for OCD symptoms.
• The findings validate a multidimensional approach to understanding OCD.
• This model is suitable for future OCD genetic linkage studies.