title: Behavioral measures and self-report of impulsivity in bipolar disorder: no association between Stroop test and Barratt Impulsiveness Scale.
abstract: BACKGROUND
  Impulsivity as a tendency to act quickly without considering future consequences has been proposed as a dimensional factor in bipolar disorder. It can be measured using behavioral tasks and self-report questionnaires. Previous findings revealed patients to show worse performance on at least one behavioral measure of impulsivity. Additionally, self-reported impulsivity seems to be higher among bipolar patients, both parameters being possibly associated with a more severe course of illness. In this study, our primary aim was to investigate the relationship between these two constructs of impulsivity among bipolar patients.
  
  
  METHODS
  A total of 40 euthymic patients with bipolar disorder (21 female, 22 Bipolar I) and 30 healthy controls were recruited for comprehensive neuropsychological assessment. To assess inhibition control as a behavioral measure of impulsivity, the Stroop Color and Word Test (Stroop) was used. Additionally, both groups completed the Barratt Impulsiveness Scale (BIS) as a self-report of impulsivity. To compare the groups' performance on the Stroop and ratings on the BIS, the non-parametric Mann-Whitney U test was used. Within the bipolar group, we additionally examined the possibility of an association between Stroop performance and BIS total scores using Pearson's Correlation r.
  
  
  RESULTS
  Patients and controls differed significantly on the Stroop and BIS, with patients performing worse on the Stroop and scoring higher on the BIS. However, there was no association between the Stroop and BIS within the bipolar group. As an exploratory analysis, a positive correlation between Stroop performance and number of episodes was found. Further, we detected a statistical trend in the direction of poorer Stroop performance among patients treated with polypharmacy.
  
  
  CONCLUSIONS
  Both difficulties with behavioral inhibition and self-reported impulsivity were observed to be higher in bipolar patients than controls in the current study. However, within the patient group we did not observe an association between patients' behavioral performance and self-report. This indicates that the parameters likely constitute distinct, dimensional factors of bipolar disorder. In future research, studies with larger samples should investigate which of the two markers constitutes the better marker for the illness and is more suitable to differentiate the most severe patients.
authors.affiliation: Dept. of Psychiatry and Psychotherapy, Charité Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany. elisa-sophie.strasser@charite.de.
authors.forename: Elisa Sophie
authors.initials: ES
authors.lastname: Strasser
authors.affiliation: Dept. of Psychiatry and Psychotherapy, Charité Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
authors.forename: Paula
authors.initials: P
authors.lastname: Haffner
authors.affiliation: Dept. of Psychiatry and Psychotherapy, Charité Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Fiebig
authors.affiliation: Dept. of Psychiatry and Psychotherapy, Charité Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
authors.forename: Esther
authors.initials: E
authors.lastname: Quinlivan
authors.affiliation: Dept. of Psychiatry and Psychotherapy, Charité Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.|Fliedner Klinik Berlin, Berlin, Germany.
authors.forename: Mazda
authors.initials: M
authors.lastname: Adli
authors.affiliation: Dept. of Psychiatry and Psychotherapy, Charité Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
authors.forename: Thomas Josef
authors.initials: TJ
authors.lastname: Stamm
keywords: Barratt Impulsiveness Scale; Bipolar disorder; Euthymic; Impulsivity; Inhibition; Stroop test