Subsequent to 1986, all family studies collected direct interview from at least some of the relatives in the family. With the exception of one study,52 all available relatives were directly interviewed. In the study by McKeon and Murray52 all family members of adult probands with OCD were given the Leyton Obsessional Inventory (LOI), and only those relatives who scored high on the LOI were directly interviewed. Only one of the interviewed relatives met criteria for OC neurosis, suggesting that the disorder is not familial.
