Neuropsychology of Bipolar Disorder; assessment techniques

Background. Bipolar Disorder (BD) is a severe mental illness with serious functional and social consequences for both patients and their families (Geddes and Miklowitz, 2013). In most BD patients mood dysregulation is accompanied by significant cognitive impairment that persists during the euthymic and acute phases (APA, 2002; MacQueen et al., 2001; Bora et al., 2009; Quraishi and Frangou, 2002). BD patients perform poorly on tests of visuomotor processing speed, verbal memory, sustained attention and executive functioning. (Bora et al., 2009; Quraishi and Frangou, 2002; Goldberg et al., 1993; Albus et al., 1996; Martínez- Aran et al., 2004a). Overall manic patients perform worse than depressed and remitted BD on verbal memory, verbal fluency, and cognitive estimation tasks (Dixon et al., 2004; Aminoff et al., 2013). Moreover, BD I patients display significant deficits in phonetic fluency, inhibition and set shifting and increased psychomotor speed during the performance of planning tasks, compared to BD II and healthy controls, without significant differences in cognitive performance between BD I and BD II patients (Pålsson et al., 2013). The persistence of verbal memory impairments across mood phases suggests that these deficit may be a stable marker for BD (Gualtieri and Johnson, 2006, Tuba et al., 2015). Although cognitive impairment is a core feature of bipolar disorder (BD), there is not any gold standard instrument for the assessment (Bauer et al., 2015). The Brief Assessment of Cognition in Affective Disorders (BAC-A) is a newly developed cognitive instrument developed specifically for BD (Keefe et al., 2014). Aim. The aim of this PhD Thesis is to assess cognitive performance in BD patients using the Brief Assessment of Cognition in Affective Disorder (BAC-A) and to compare the cognitive performance between patients with DSM-IV bipolar disorder type I and bipolar disorder type II and matched healthy controls and to test the role on cognition of mood state at the time of cognitive assessment.Methods. The BAC-A was administered to 47 patients with DSM-IV BD type I, 23 patients with DSM-IV BD type II disorder BD patients and 70 healthy controls. The scores of the BAC-A were combined in seven summary scores: visuo-motor, immediate affective and non-affective memory, verbal fluency, delayed affective memory, inhibition, and problem solving. Results. Compared to HC, BD patients showed a significant impairment in the short-term affective and non-affective memory, visual motor domain and verbal fluency. There were no statistically significant differences between BD I and BD II patients in cognitive domains assessed. According to the mood state, the sample of patients with BD differ with respect to scores at BRMRS (p<0.01) and relative to cognition: BD patients in euthymic phase performed significantly better than BD patients in manic phase in short-term affective memory (p=0.02) and in in short-term non-affective memory (p= 0.01); while, BD patients in depressive phase performed significantly better than BD patients in manic phase in short-term affective memory (p=0.02).There is also a significant difference between BD patients in euthymic a and BD patients in depressive phase for the age of disease onset (p=0.03).Conclusions. The present study suggests that cognitive dysfunction is similar in both BD I and II; indeed, BD I and BD II patients did not present significant differences on BAC-A subdomains. On the the role of the phase of illness, the results suggest that manic phase is associated with a worse performance in short-term affective memory and short-term non affective memory compared to euthymic and depressive phase.