No evidence of differences in neurocognitive functioning among euthymic bipolar I and bipolar II disorders

MARTINO D.J, IGOA A., MARENGO E., FASSI G., STREJILEVICH S.A.

Amsterdam, Holanda

Congreso; 23rd Euroean College Neurpsychopharmacology Congress; 2010

Background: A growing body of evidence suggests that patients with BD have impairments in verbal memory, attention, and executive function even during euthymic periods [1]. Almost all of these studies were conducted with patients with bipolar I disorder (BDI) or mixed samples of BDI and bipolar II disorder (BDII). Studies focalized in neucognitive functioning of patients with bipolar II disorder (BDII) brought evidence about impairments in this population although some results were inconsitent [2, 3]. Moreover, just one study assessed the relationship between neurocognitive impairments and functional outcome [2]. Then, the aim of this study was to compare neurocognitive functioning between euthymic patients with BDI, BDII, and healthy controls. An additional aim was to estimate the relationship between neurocognitive impairments and psychosocial functioning. Methods: Eighty-seven euthymic patients with BDI (n=48) or BDII (n=39) and 39 healthy controls were included. All subjects completed tests to assess premorbid IQ, verbal memory, attention, psychomotor speed, and executive functions. The three groups (BDI, BDII, and healthy controls) were compared in clinical-demographical variables using analysis of variance (ANOVA) and chi squared tests as appropriate. One-way multivariate analyses of variance was conducted with all neurocognitive variables as dependent variables and group membership as factor. Difference between three groups were analyzed with one-way ANOVA, followed by Tukey post hoc comparison procedure when significant main effects were present. The effect sizes have been calculated to find the differences between the groups in terms of standard deviation. Pearson correlation coefficients were calculated to test for the associations between clinical and neurocognitive variables with psychosocial functioning as measured by the GAF. The neurocognitive variables with significant correlation with psychosocial functioning (GAF) were considered as possible explanatory variables in a multiple linear regression model. Results: No differences between groups were found on clinical-demographical variables such as age, gender, education, premorbid IQ, and scores in Young Mania Rating Scale and Hamilton Depression Rating Scale (all p >0.05). A significant overall difference in neurocognitive functioning between the groups was detected with multivariate analysis of variance (PillaiLs F=1.77; df=28, 216; P=0.013). For 8 of 14 comparisons the differences reached statistical significance (P<0.05); the group mean performance for each neurocognitive measure and the respective analysis of variance are presented in table 1. Both patients groups did not show differences in any of cognitive masures assessed. Performance in trail making test B was the only independent predictor of psychosocial functioning in both patients witn BDI (ƒÀ=-0.41; t=-2.82; P=0.006) and BDII(ƒÀ=-0.52; t=-3.18; P=0.003). Conclusions: Our results bring additional support to the notion that BDII disorder is not a  merely mild BDI. Regardless healthy controls, patients with BDII had impairments in verbal memory, psychomotor speed, and executive function, Additionally,  cognitive impairments and particularly executive dysfunction were related with poor psychosocial functioning in patients with BDII. Cognitive impairments would be a rational target of treatment in patients with BD.