LAUSR

Background Bipolar Disorder is characterised by opposite fluctuations of mood and goal-directed behaviours (i.e. manic and depressive episodes) interspersed with period of stability (i.e. euthymia). Deficit in executive control have been observed both in the prodromal phases of the disorder and in euthymia, suggesting a trait feature. Recent models of Bipolar Disorder postulate that an imbalance between an increased bottom-up reward sensitivity and a reduced top-down prefrontal control [1] might be responsible of the phenomenology of the disorder. Aims First, evaluate whether a sample of subjects with Bipolar Disorder, compared with healthy controls, show an impairment in the attentional networks and an increased behavioural activation. Secondly explore possible interactions of these characteristics with symptoms domains. Methods Thirty-five subjects with Bipolar Disorder and 35 matched healthy controls completed an attentional task (Attentional Network Task Revised, ANT-R) [2]. Participants were assessed on temperament (ATQ), behavioural activation/inhibition (BIS-BAS), disorder of thinking (STOQ) and manic/depressive symptoms (HDRS and YMRS). Groups were compared in the task outputs on the three attentional networks (alerting, orienting and executive attention). Differences were first controlled for confounding variables (e.g. age) and then added in a GLM aimed at evaluate the best predictor of the measured clinical dimensions. Significant interactions were further explored through mediation and moderation analyses. Results Compared to healthy controls, subjects with Bipolar Disorder scored significantly higher (i.e. worse performance) only in the reaction time at the Flanker effect (t=-3.560; p Discussion Our results, even though limited by the small sample size, suggest that subjects with Bipolar Disorder show an impairment in attention and specifically in the executive control. This prefrontal impairment might be responsible for the thoughts over-activation observed in euthymic subjects, as a dimension that goes from depressive rumination to acceleration of ideas. This relationship, however, depends on the subject levels of behavioural activation; in fact at high level of reward responsiveness, the prefrontal control might lose its top-down effect on symptoms phenomenology. Conclusions Treatments aimed at targeting both reward and attention circuits [3] might improve the course of the disorder. Further studies, including a computational approach to information integration in attentional tasks [4] should confirm our preliminary results and test the hypothesis of a learning impairment in the genesis and maintenance of Bipolar Disorder [5].