A New Approach to Emotional Dysregulation in Bipolar Disorder

Abstract

Bipolar disorder (BD) is a mental disorder characterized by periods of mania and depression that, even during asymptomatic states (i.e., euthymia), involves a mood dysregulation [1]. Mood dysregulation has been included as a new clinical entity for BD in the last publication of the Diagnostic and Statistical Manual of Mental Disorders [2]. However, the nosologic relationship between BD and mood dysregulation is still an unsolved issue [3].At the theoretical level, cognitive vulnerability models [4] assume that the dysfunction for inhibiting mood-congruent stimuli represent an important component of emotion dysregulation in BD. In particular, negative biases in depression or positive biases in mania may evoke extreme emotional responses that require more effortful inhibitory control [5]. However, this extrapolation to BD of Beck's Cognitive Theory of Depression (i.e., biases towards happy stimuli in mania and sad stimuli in depression; [6] has not always been supported at empirical level.To understand the emotion dysregulation entailed in these BD periods, it is fundamental to examine whether or not patients are voluntarily exercising control over the emotional information processing [5]. To our knowledge, only one eye-tracking study has examined the inhibitory attention control of emotional stimuli comparing BD patients in their manic, depressive, and euthymic periods [7]. Applied an emotional antisaccade experiment with "happy", "sad", and "neutral" faces to BD patients. In antisaccade blocks, participants were required to inhibit the automatic prosaccade and voluntarily generating an antisaccade to the mirror position. Results showed that while manic BD patients committed more antisaccade errors when the target face was a happy one, depressed BD patients committed more antisaccade errors when the target face was a sad one. No differences were found in euthymic BD patients or healthy individuals. Thus, [7] findings suggest that BD patients had more difficulties for voluntarily controlling their attention towards mood-congruent stimuli during symptomatic states.Alternatively, the attentional biases towards emotional information in BD have also been studied in more ecological scenarios, such as the free-viewing task without restricted instructions. In the [8] experiment, BD patients were simultaneously viewed with four complex scenes with different emotional valence (happy, neutral, sad, threatening) for 20s while their eye movements were registered. BD patients, regardless of their episode, showed greater attention to threatening pictures than healthy individuals. In addition, depressed BD patients showed less attention to happy images than healthy participants. These differences were observed in the overall allocation of attention (i.e., percent fixation time and percent fixations) but not in ealier attentional capture (i.e., first-pass duration and location of the initial fixation). While these data from [8] are relevant to determine the interplay of the attentional biases in the different episodes of BD, ther...