Obsessional slowness in obsessive-compulsive disorder: identifying characteristics and comorbidities in a clinical sample.

This is the largest-scale descriptive study of OS, which also provides preliminary evidence that OS may be a more severe form of OCD. Further empirical validation of these findings is required, and future research should focus on developing OS assessment.Key PointsThis was the first large-scale descriptive study of obsessional slowness (OS), that provided preliminary evidence for an OS phenotype within obsessive-compulsive disorderOS is associated with increased severity of aggression, contamination, symmetry and hoarding obsessive-compulsive symptomsIndividuals with OS are more likely to have comorbid tics, suggesting that there may be underlying motor factors contributing to this conditionFuture research would benefit from collecting both qualitative and quantitative data when assessing OS.