Exclusion criteria were as follows: (1) subjects with schizophrenia, severe intellectual disability, or another condition preventing evaluation; (2) Tourette disorder without OCD; (3) OCD-like symptoms occurring exclusively in the context of depression; and (4) previous diagnosis of brain pathology, including brain tumors, Huntington's disease, Parkinson's disease, or Alzheimer's disease. Final diagnostic status was assigned based on the consensus of two psychiatrists or psychologists reviewing the case independently followed by review by one of five consensus psychiatrists as described previously (Samuels et al. 2006). Probands with a diagnosis of “probable” or “definite” OCD were included.
