Demographic and clinical characteristics of the study sample
| Group; no. (%) or mean ± SD | ||||
|---|---|---|---|---|
| Characteristic | BD, n = 172 | Control, n = 146 | Statistic | p value |
| Women | 95 (55.2) | 74 (50.7) | χ21,318 = 0.656 | 0.67 |
| Right-handed | 161 (93.6) | 139 (95.2) | χ22,318 = 0.382 | 0.87 |
| Site | χ23,318 = 6.621 | 0.27 | ||
| 1) France | 23 (13.4) | 22 (15.1) | ||
| 2) United States | 52 (30.2) | 26 (17.8) | ||
| 3) Germany | 37 (21.5) | 38 (26.0) | ||
| 4) Ireland | 60 (34.9) | 60 (41.1) | ||
| History of psychotic features* | 113 (65.7) | — | — | — |
| Positive history of alcohol abuse or dependence | 35 (20.3) | — | — | — |
| Age at MRI, yr | 37.9 ± 10.41 | 39.2 ± 10.8 | t316 = 1.016 | 0.67 |
| Age at onset, yr | 23.4 ± 8.8 | — | — | — |
| Duration of illness, yr | 14.54 ± 9.1 | — | — | — |
| MADRS score (2 sites) | 3.2 ± 4.8 | — | — | — |
| HAMD-19 score (1 site) | 4.96 ± 7.1 | — | — | — |
| HAMD-25 score (1site) | 12.58 ± 10.24 | — | — | — |
| YMRS score (4 sites) | 1.8 ± 3.2 | — | — | — |
| Brain volume, cm3 | 1429.2 ± 153.5 | 1437.9 ± 145.7 | t316 = 0.521 | 0.72 |
BD = bipolar disorder; HAMD = Hamilton Rating Scale for Depression; MADRS = Montgomery–Åsberg Depression Rating Scale; SD = standard deviation; YMRS = Young Mania Rating Scale.
↵* Data on psychotic features missing for 1 participant.