Dissociative experiences differentiate bipolar-II from unipolar depressed patients: the mediating role of cyclothymia and the Type A behaviour speed and impatience subscale.

BACKGROUND

Dissociative symptoms are often seen in patients with mood disorders, but there is little information on possible association with subgroups and temperamental features of these disorders.

METHODS

The Dissociative Experience Scale was administered to 85 patients with a DSM-IV Major Depressive Disorder (MDD) or Bipolar-II Disorder (BP-II). Both broad-spectrum dissociation (DES total score) and clearly pathological forms of dissociation (DES-Taxon) were assessed. Temperament was assessed using Akiskal and Mallya;s criteria of Affective Temperaments and the Jenkins Activity Survey (JAS) for Type A Behaviour.

RESULTS

Sixty-five patients gave valid answers to DES. The mean DES and DES-T scores were higher in BP-II (16.8 and 12.7 respectively) compared to MDD (9.0 and 5.7); DES odds ratio (OR)=1.58 (95% CI 1.15-2.18) and DES-T OR=1.60 (95% CI 1.14-2.25) using univariate logistic regression analyses. There was no significant difference in DES score in patients with (n=30) and without an affective temperament (n=35): mean (95% CI), 13.5 vs. 10.5 (-7.8 to 1.9), p=0.224. However the subgroup with a cyclothymic temperament (n=18) had higher DES scores (mean (95% CI): 17.8 vs. 9.7 (2.9-13.3), p=0.003), compared to patients without such a temperament. There was no significant difference in DES scores for patients with (n=35) or without (n=28) a Type A behaviour pattern (JAS>0): mean (95% CI) 12. 7 vs. 10.9 (-6.8 to 3.3), p=0.491), but a positive JAS factor S score (speed and impatience subscale) was associated with significantly higher DES scores than a negative S-score: mean (95% CI) 14.9 vs. 9.0 (1.1-10.7), p=0.017), and this was still significant (p=0.005) using multiple linear regression of DES scores vs. the JAS subscale scores. DES-T scores were significantly higher in patients with OCD (n=9) (mean (95% CI) 18.4 vs. 6.6 (6.0-17.7), p<0.001); eating disorder (n=13) (14.0 vs. 6.8 (1.8-12.6), p=0.009), psychotic symptoms during depressions (n=9) (16.6 vs. 6.9 (3.7-15.8), p=0.002), and in those with a history of suicide attempt (n=28) (11.9 vs. 5.4 (2.2-10.8), p=0.003), but only OCD was an independent predictor after multiple linear regression of DES-T scores vs. all co-morbid disorders (p=0.043).

LIMITATIONS: The major limitation of the present study is a non-blind evaluation of affective diagnosis and temperaments, and assessment in a non-remission clinical status.

CONCLUSIONS

Dissociative symptoms measured with the Dissociative Experience Scale are associated with bipolar features, using formal DSM-IV criteria, cyclothymic temperament and the speed and impatience subscale of the JAS.