Demographic information is shown in Table 1. A total of 1401 probands met inclusion criteria. Probands had an average age of 27.8 ± 14.1 years (median 25 years) with a history of symptom onset at 7.7 ± 3.5 years and diagnosis at 10.1 ± 3.7 years. One-third (33%) were age 18 or under at the time of assessment. Approximately half (56%) were female and 91% identified as Caucasian or White. At the time of assessment, females were on average older than males [mean age 29.7 ± 14.3 vs. 25.4 ± 13.4 years, t(1399) = −5.741, p < 0.001, n = 1401] and had experienced OCD symptom onset at a younger age [7.5 ± 3.3 vs. 8.1 ± 3.7 years, t(1239) = 3.369, p = 0.001, n = 1398].
