Table 1 Participant characteristics at baseline

Sample size

39

34

Study site

Χ² = 0.170, df = 2, p = 0.919

 Berlin

20 (51.3)

19 (55.9)

 Chemnitz

8 (20.5)

6 (17.6)

 Dresden

11 (28.2)

9 (26.5)

Demographics

 Sex

Χ² = 0.088, df = 1, p = 0.766

  Females

17 (43.6)

16 (47.1)

  Males

22 (56.4)

18 (52.9)

 Age [years]

44.32 ± 11.63

42.69 ± 12.34

t = 0.581, df = 71, p = 0.563

Clinical data

 Bipolar subtype

Χ² = 3.840, df = 1, p = 0.050

  Type I

24 (61.5)

28 (82.4)

  Type II

15 (38.5)

6 (17.6)

 Age at disease onset [years]

28.87 ± 11.72

26.68 ± 9.87

U = 383.0, z = − 0.775, p = 0.438

 Previous episodes

14.83 ± 23.35

15.47 ± 17.45

U = 566.5, z = 0.342, p = 0.732

 Hospitalizations

3.18 ± 4.59

3.21 ± 2.77

U = 823.0, z = 1.792, p = 0.073

 History of rapid cycling

4 (10.3)

8 (23.5)

Χ² = 2.330, df = 1, p = 0.127

 History of suicide attempts

16 (41.0)

11 (32.4)

Χ² = 0.718, df = 1, p = 0.397

 Psychotropic drugs

1.82 ± 0.89

2.09 ± 1.08

U = 746.5, z = 0.975, p = 0.329

 Individual psychotherapy ever received

25 (64.1)

29 (85.3)

Χ² = 4.237, df = 1, p = 0.040*

 Group psychotherapy ever received

17 (43.6)

12 (35.3)

Χ² = 0.522, df = 1, p = 0.470