Differences in sample characteristics between study groups
| Ashkenazi (n = 132) | Costa Rican (n = 119) | Sibling pairs (n = 46) | Total (n = 297) | F statistic (2 df) or χ2 | p value | |
|---|---|---|---|---|---|---|
| Socioeconomic status (SES) is measured using the Hollingshead rating scale.27 | ||||||
| Mean motor and phonic tic severity was measured using the YGTSS. | ||||||
| *Fisher p value. | ||||||
| Male, % | 73.7 | 80.8 | 78.3 | 77.3 | 1.87 | 0.39 |
| Mean (SD) age at interview, years | 22.5 (15.0) | 15.8 (11.9) | 20.4 (14.7) | 19.5 (14.1) | 7.47 | 0.0007 |
| SES | 2.6 (1.1) | 3.1 (0.9) | 2.7 (1.3) | 2.8 (1.1) | 3.47 | 0.03 |
| Mean (SD) tic severity | ||||||
| Motor | 13.0 (2.3) | 10.3 (1.9) | 11.5 (2.8) | 11.7 (2.6) | 48.7 | <0.0001 |
| Phonic | 11.7 (3.2) | 8.1 (2.4) | 10.1 (2.4) | 10.0 (3.4) | 47.0 | <0.0001 |
| Psychiatric comorbidities, % | ||||||
| OCD | 61.4 | 4.3 | 71.1 | 40.1 | 105.35 | <0.0001 |
| ADHD | 43.9 | 23.5 | 69.6 | 39.7 | 31.1 | <0.0001 |
| OCD+ADHD | 34.6 | 3.3 | 58.7 | 25.8 | 63.1 | <0.0001 |
| SIB | 43 | 14 | 28 | 29 | 25.3 | <0.0001 |
| Severe SIB | 5 | 1 | 7 | 4 | 4.7 | 0.055* |