Aims:
Decision making, as well as working memory and executive functions are among the most significant cognitive processes, associated with prefrontal cortex function. Decision making is associated mostly with the orbitofrontal cortex function, however working memory and executive functions are dependent on the dorsolateral prefrontal cortex activity. Orbitofrontal, as well as dorsolateral prefrontal cortex dysfunction in bipolar disorder has been reported. The aim of the study was to assess decision making and executive functions in remitted bipolar patients.
Methods:
The study included 30 euthymic bipolar patients (16 female,14 male), aged 40±13 years and 30 age, sex and education years matched healthy controls.
Decision making was assessed with Iowa Gambling Task (IGT). Working memory and executive functions were assessed with Wisconsin Card Sorting Test (WCST) and Trail Making Test (TMT). Depressive and/ or manic symptoms were measured with Hamilton Depression Scale (HAM-D) and Young Mania Rating Scale (YMRS).
Results: No significant differences in performance on IGT between euthymic bipolar patients and healthy subjects were found. Bipolar patients made more perseverative(t=3,27;p= 0,00) and nonperseverative errors (t=4,09; p=0,00), gave less conceptual level responses (t=-4,73;p=0,00), completed less correct categories (t=-4,73;p=0,00) and used more cards to complete first category (t=2,47;p=0,017) in WCST. They also needed more time to complete part A (t=3,88;p=0,00) and B (t=3,81;p=0,00) of TMT. Conclusions:
Bipolar patients performed significantly worse on all measures of WCST as well as in TMT test. This suggests a deficit in executive functions but not in decision making in euthymic phase of bipolar disorder.