Clusters of obsessive-compulsive phenomena in obsessive-compulsive disorder.

Clusters of phenomena were obtained by two clustering techniques, using the form and content of obsessions and compulsions. Significant clusters which emerged involved washing, checking, thoughts of past, and embarrassing behaviour. Depression occurred as a discrete cluster. Eighty-nine per cent of subjects could be fitted into at least one cluster; over half could be fitted into only one cluster. Washers and checkers made up more than half of the sample studied.