Towards a definitive symptom structure of obsessive-compulsive disorder: a factor and network analysis of 87 distinct symptoms in 1366 individuals.

Ygor A Ferrão,David Mataix-Cols,James F Leckman,Daniel A Geller,Sebla Gökçe,Maria Conceição Do Rosário,Ayşegül Selcen Güler,Yankı Yazgan,Matti Cervin,Ayşe Burcu Erdoğdu,Leonardo F Fontenelle,Şaziye Senem Başgül,Özlem Özcan,Euripedes C Miguel,Luisa Lazaro,Eric A Storch,Yasemin Yulaf,Koray Karabekiroğlu

doi:10.1017/s0033291720005437

Abstract

The symptoms of obsessive-compulsive disorder (OCD) are highly heterogeneous and it is unclear what is the optimal way to conceptualize this heterogeneity. This study aimed to establish a comprehensive symptom structure model of OCD across the lifespan using factor and network analytic techniques. A large multinational cohort of well-characterized children, adolescents, and adults diagnosed with OCD (N = 1366) participated in the study. All completed the Dimensional Yale-Brown Obsessive-Compulsive Scale, which contains an expanded checklist of 87 distinct OCD symptoms. Exploratory and confirmatory factor analysis were used to outline empirically supported symptom dimensions, and interconnections among the resulting dimensions were established using network analysis. Associations between dimensions and sociodemographic and clinical variables were explored using structural equation modeling (SEM). Thirteen first-order symptom dimensions emerged that could be parsimoniously reduced to eight broad dimensions, which were valid across the lifespan: Disturbing Thoughts, Incompleteness, Contamination, Hoarding, Transformation, Body Focus, Superstition, and Loss/Separation. A general OCD factor could be included in the final factor model without a significant decline in model fit according to most fit indices. Network analysis showed that Incompleteness and Disturbing Thoughts were most central (i.e. had most unique interconnections with other dimensions). SEM showed that the eight broad dimensions were differentially related to sociodemographic and clinical variables. Future research will need to establish if this expanded hierarchical and multidimensional model can help improve our understanding of the etiology, neurobiology and treatment of OCD.

Highlights

Phenotypic validity is crucial for identifying causal and maintaining mechanisms in mental disorders (Insel et al, 2010)
The theory-derived six-factor model of the Dimensional Y-BOCS (DY-BOCS) exhibited a poor fit in the full sample, as did the single-factor model
In line with our statistical plan, we randomly split the sample into two groups (40/60% of the total sample) and performed an exploratory factor analysis (EFA) based on the first 40% (n = 547) to derive an empirically supported factor structure

Summary

Introduction

Phenotypic validity is crucial for identifying causal and maintaining mechanisms in mental disorders (Insel et al, 2010). The only meta-analysis to date suggested four symptom dimensions: forbidden thoughts, hoarding, symmetry, and contamination/ cleaning (Bloch, Landeros-Weisenberger, Rosario, Pittenger, & Leckman, 2008). Other dimensional models have been suggested, with some evidence suggesting that the forbidden thoughts factor may best be split into two separate factors entailing symptoms of responsibility/harm and sexual/religious concerns, respectively (Miguel et al, 2008; Torres et al, 2016). It is currently unclear whether a similar symptom structure of OCD is present across the lifespan, which is important because childhood-onset OCD may constitute a somewhat different patient group (Leckman et al, 2010). Future research will need to establish if this expanded hierarchical and multidimensional model can help improve our understanding of the etiology, neurobiology and treatment of OCD

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Discussion

Conclusion