OCD symptoms in children and teens: factor structure and genetic influences in twins

What is it about?

This study tested whether a widely used questionnaire for measuring obsessive-compulsive symptoms in young people, the Short Leyton Obsessional Inventory, Children's Version (Short LOI-CV), captures one broad dimension of OCD or several distinct ones. Using a general population sample of 517 adolescent twins aged 11 to 16, the researchers compared three competing structural models: a single overall OCD factor, a two-factor obsessions and compulsions model, and a three-factor model covering Obsessions and Incompleteness, Numbers and Luck, and Cleanliness. The three-factor model best explained the data. Twin analyses then examined genetic contributions to each dimension and found significant sex differences, with the Obsessions and Incompleteness and Numbers and Luck dimensions substantially heritable in boys (around 60% and 65% respectively) but not in girls.

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Why is it important?

OCD is typically classified as a single diagnostic category, yet evidence increasingly points to meaningful subtypes with different causes and treatment responses. This study challenges the single-factor assumption embedded in standard diagnostic classifications and demonstrates that OCD symptoms in young people are multidimensional with distinct genetic profiles. The finding that heritability differs by sex and by symptom dimension has direct implications for genetic research, early identification, and targeted intervention. Using a community twin sample adds population-level validity, making this study an important contribution to developmental psychopathology, OCD genetics, and the psychometric assessment of obsessive-compulsive symptoms in children and adolescents.