Cognitive impairment in bipolar II disorder
¤ CARLA TORRENT, ANABEL MARTI¤NEZ-AR AN, CLAIRE DABAN, MARTINEZ-ARAN, ¤ ' ¤ JOSE SA NCHEZ-MORENO, MERCE COMES, JOSE MANUEL GOIKOLEA, SANCHEZ-MORENO, MANEL SALAMERO and EDUARD VIETA
Background Persistentimpairmentsin neurocognitive function have been described in bipolar disorder. Aims To compare the cognitive performance of patients with bipolar II disorder withthatof patients with bipolar I disorder and a healthy control group. Method The study included 71 euthymic patients with bipolar disorder (38 bipolar I, 33 bipolar II), who were compared on clinical and neuropsychological variables (e.g.executive function, attention, verbal and visual memory) and contrasted with 35 healthy controls on cognitive performance. Results Compared with controls, both bipolar groups showed significant deficits in most cognitive tasks including working memory (DigitSpan Backwards, P¼0.002) and attention (DigitSpan 0.002) Forwards, P¼0.005;Trail MakingTest, 0.005;Trail P¼0.001).Those with type II disordershad 0.001).Those an intermediate level of performance between the bipolar I group and the control group in verbal memory (P50.005) and executive functions (Stroop interference task, P¼0.020). 0.020). Conclusions Cognitive impairment exists in both subtypes of bipolar disorder, although more so in the bipolar I group. The best predictors of poor psychosocial functioning in bipolar II disorder weresubclinical depressive symptoms, early onsetof illness and poor performance on a measure related to executive function. Declaration of interest None. Funding detailed in Acknowledgements.
There is increasing evidence that several cognitive areas are impaired during the acute phases of bipolar illness and that this impairment persists even in the euthymic periods (van Gorp et al, 1998; Ferrieret al, al, 1999; Cavanagh et al, 2002; Clark et al, al, al, 2002; Altshuler et al, 2004; Martinezal, al, Aran et al, 2004a,b; Thompson et al, al, 2004a al, 2005). To date investigations on neurocognitive functioning have not distinguished between bipolar subtypes. The bipolar II population has not been assessed in this aspect, mainly because of the small number of patients with type II disorderincluded in these studies. Furthermore, in recently published studies only patients with bipolar I disorder were investigated (Donaldson et al, 2003; Altshuler et al, al, al, 2004; Dixon et al, 2004; Balanza-Martinez al, et al, 2005; Deckersbach et al, 2005; Fleck al, al, et al, 2005; Kravariti et al, 2005). Factors al, al, that have been reported to influence negatively cognitive functioning inbipolar disorder, with a negative impact on the performance of tasks on memory, attention and abstraction (McKay et al, 1995; al, Zubieta et al, 2001; Martinez-Aran et al, al, al, 2004a,b), are the number of episodes (espe2004a cially manic episodes), the number of hospitalisations, the occurrence of psychotic symptoms and chronicity defined as duration of the illness. These factors have not, however,been specifically investigated in bipolar II disorder. Cognitive impairment, particularly memory difficulties, may also have negative implications in the functional outcome of patients with bipolar disorder (Martinez-Aran et al, 2004a,b; al, 2004a 2006). Between 30% and 50% of patients with bipolar disorder experience significant social disability that may be related to persistent cognitiveimpairment (Zarate et al, al, 2000; Dickerson et al, 2004), but again al, these studies are not specifically focused on bipolar II disorder. Additionally, subsyndromal features may have a negative impact in neuropsychological impairment and psychosocial functioning (Cassano &
Savino, 1997; Fava, 1999; Benazzi, 2001; Clark et al, 2002; Martinez-Aran et al, al, al, 2002). The main aim of our study...