Obsessional beliefs, compulsive behaviours and symptom severity: their evolution and interrelation over stages of treatment.

The current study reports a case series examining (1) the variation in strength of obsessional doubt and belief in consequences of the doubt; and (2) the interaction between these cognitive components and symptom measures of duration and severity of obsessive-compulsive disorder (OCD), over 24 weeks of cognitive behaviour therapy. Eight participants diagnosed with OCD, four with contamination-related rituals and four with checking behaviours, were selected on the basis of the Yale-Brown obsessive-compulsive scale (Y-BOCS) and Padua ratings. All participants completed daily diaries measuring strength of principal obsessional doubt (0-100), strength of belief in consequences of the doubt (0-100) and the duration of the compulsive rituals throughout the 24 weeks of therapy. Severity of symptomatology was measured pre- and post-treatment using the Y-BOCS. Change in all measures was analysed over time following the procedure outlined by Storchheim and O'Mahoney (2006). Results showed that decrease in belief in secondary consequences is always accompanied by a decrease in strength of obsessions, but the converse does not hold. Furthermore, change in OCD symptomatology may precede cognitive changes. Copyright (c) 2008 John Wiley & Sons, Ltd.