Table 1.
Characteristics of the bipolar depression (BD), unipolar depression (UD), and healthy control (HC) groups
| BD | UD | HC | p value | Interpretation, post-hoc | |
|---|---|---|---|---|---|
| N (% female) | 21 (33.3%) | 27 (40.7%) | 31 (58.1%) | 0.176a | n.s |
| Age (years) | 43.5 ± 9.8 | 39.6 ± 15.3 | 41.7 ± 14.3 | 0.591b | n.s |
| Education in years | 16.8 ± 4.0 | 15.5 ± 3.1 | 16.5 ± 3.8 | 0.453c | n.s |
| N lefthanders (%) | 1 (4.8%) | 2 (7.4%) | 1 (3.2%) | –d | –d |
| Age of first episode | 24.7 ± 9.5 | 29.5 ± 15.2 | – | 0.182b | n.s |
| Years since first episode | 18.9 ± 13.5 | 10.1 ± 9.4 | – | 0.161b | n.s |
| Number of depressive episodes | 7.2 ± 6.1 | 4.8 ± 3.8 | – | 0.095c | n.s |
| Number of manic episodes | 2.9 ± 3.6 | – | – | – | – |
| Number of hypomanic episodes | 3.3 ± 5.0 | – | – | – | – |
| BDI-II visit 1 | 21.1 ± 16.7 | 29.5 ± 11.1 | 2.6 ± 3.7 | < 0.001b | Games-Howell post-hoc test: difference HC and UD: p < 0.001, HC and BD: p < 0.001, UD and BD: p = 0.128 |
| BDI-II visit 2 | 17.1 ± 13.1 | 20.2 ± 14.0 | 2.3 ± 4.2 | < 0.001b | Games-Howell-post-hoc-test: difference HC and UD: p < 0.001, HC and BD: p < 0.001, UD and BD: p = 0.714 |
| Delta BDI-II visit 2–visit 1 | − 3.9 ± 13.3 | − 9.3 ± 11.9 | -0.2 ± 2.6 | 0.009b | Games-Howell-post-hoc-test: difference HC and UD: p = 0.002, HC and BD: p = 0.437, UD and BD: p = 0.327 |
| MADRS visit 1 | 13.9 ± 10.6 | 24.2 ± 8.6 | – | 0.001c | Severity of depressive symptoms is higher in UD |
| MADRS visit 2 | 10.5 ± 8.3 | 14.3 ± 10.2 | – | 0.179c | n.s |
| Delta MADRS visit 2 – visit 1 | − 3.3 ± 9.3 | − 9.9 ± 10.3 | – | 0.028c | Reduction in the severity of depressive symptoms is higher in UD |
| YMRS visit 1 | 6.1 ± 6.9 | 1.7 ± 2.6 | – | 0.012b | Severity of manic symptoms (mixed episode) is higher in BD |
| YMRS visit 2 | 2.3 ± 3.5 | 1.4 ± 1.7 | – | 0.222b | n.s |
| Delta YMRS visit 2 – visit 1 | − 3.7 ± 6.2 | − 0.3 ± 2.1 | – | 0.025b | Reduction in the severity of manic symptoms (mixed episode) is higher in BD |
| Medication load visit 1 | 4.5 ± 2.4 | 4.3 ± 3 | 0 ± 0 | No p value because of a variance of 0 in controlsb | Games-Howell post-hoc test: difference HC and UD: p < 0.001, HC and BD: p < 0.001, UD and BD: p = 0.938 |
| Medication load visit 2 | 3.8 ± 2.3 | 4.1 ± 2.6 | 0 ± 0 | No p value because of a variance of 0 in controlsb | Games-Howell post-hoc test: difference HC and UD: p < 0.001, HC and BD: p < 0.001, UD and BD: p = 0.925 |
| Delta medication load visit 2–visit 1 | − 0.7 ± 2.5 | − 0.2 ± 1.9 | 0 ± 0 | No p value because of a variance of 0 in controlsb | Games-Howell post-hoc test: difference HC and UD: p = 0.867, HC and BD: p = 0.405, UD and BD: p = 0.700 |
p<0.05 are shown in bold
aChi-square test
bOne-way ANOVA with Brown-Forsythe correction for inhomogeneity of variance
cOne-way ANOVA with homogeneity of variance
dAnalysis repeated without lefthanders
BD bipolar depressed, BDI-II Beck depression inventory-second edition, HC healthy controls, MADRS montgomery–Åsberg depression rating scale, UD unipolar depressed, YMRS Young mania rating scale