Differentiating bipolar I disorder, bipolar II disorder and unipolar depression based on neurobiological alterations of Grays behavioral activation and inhibition system (BAS/BIS)

双相情感障碍是一种毁灭性的精神疾病，其特征是反复发作的抑郁和情绪升高。由于我们对双相情感障碍病因的了解相当有限，诊断是基于行为表现。其副作用是，在发病时双相情感障碍，特别是双相情感障碍II型，经常被误诊为单极抑郁症，从而对病程产生不利影响。有趣的是，双相情感障碍和单极情感障碍都可以被视为异常动机障碍，这里指的是启动、控制和维持行为的过程，目的是使愉快的结果最大化。抑郁症患者对几乎所有活动的兴趣都减少了，而躁狂患者则表现出对愉快活动的过度参与，这很可能导致长期的负面后果。人们认为，减少（抑郁）/增加（躁狂）对食欲刺激的接近动机以及增加（抑郁）/减少（躁狂）对厌恶刺激的处理与行为激活系统（BAS）的改变有关。此外，行为抑制系统（BIS）在接近-回避冲突中调节BAS的改变也可能与情绪障碍有关。第一个证据也表明，反刍指的是关于一个话题的反复的、通常是现实的想法，它介导了bas敏感性增加和躁狂症状之间的联系。然而，在情感性障碍患者中，BAS、BIS和反刍以及它们的神经生物学相关性尚未得到系统的研究。本研究拟调查三组患者：双相I型、双相II型和单相抑郁症的接近、回避行为和反刍行为。应用磁共振成像（MRI），我们希望识别功能性生物标志物，使这些疾病具有足够的敏感性和特异性。在核磁共振期间，参与者将接受广泛的临床诊断、神经心理学测试、避免接近任务和反刍任务。数据将在一般线性模型和机器学习算法的背景下进行分析。

Bipolar disorder is a devastating mental disease characterized by recurrent episodes of depressed and elevated mood. As our knowledge concerning the etiology of bipolar spectrum disorders is rather limited, diagnosis is based on behavioral manifestations. This has the side effect that at onset bipolar spectrum disorders and in particular bipolar II disorder are often misdiagnosed as unipolar depression leading to detrimental effects on the course of the disease. Interestingly, both bipolar and unipolar affective disorders might be seen as disorders of aberrant motivation herein referring to the process of initiating, controlling and maintaining behavior with the goal of maximizing pleasurable outcomes. During depression a diminished interest in almost all activities is observed, whereas during mania patients display excessive involvement in pleasurable activities with a high probability of negative long-term consequences. It is assumed that reduced (depression) / increased (mania) approach motivation towards appetitive stimuli as well as increased (depression) / reduced (mania) processing of aversive stimuli, is related to alterations in the behavioral activation system (BAS). Further, alterations in the behavioral inhibition system (BIS) that regulates the BAS in case of approach-avoidance conflicts might also be of relevance in mood disorders. First evidence also suggests that rumination referring to repeated, often realistic thoughts concerning one topic mediates the association between increased BAS-sensitivity and manic symptoms. However, BAS, BIS and rumination as well as their neurobiological correlates have not been systematically studied in patients with affective disorders. The proposed study likes to investigate three patient groups: bipolar I disorder, bipolar II disorder and unipolar depression with regard to approach and avoidance behavior and rumination. Applying magnetic resonance imaging (MRI), we like to identify functional biomarkers that allow differentiation of these disorders with sufficient sensitivity and specificity. Participants would undergo extensive clinical diagnostics, neuropsychological testing, an approach-avoidance task and a rumination task during MRI. Data will be analyzed in the context of the general linear model and with machine learning algorithms.