Opel Nils, Redlich Ronny, Grotegerd Dominik, Dohm Katharina, Haupenthal Cordula, Heindel Walter, Kugel Harald, Arolt Volker, Dannlowski Udo
Department of Psychiatry, University of Münster, Münster, Germany.
Hum Brain Mapp. 2015 Jun;36(6):2330-7. doi: 10.1002/hbm.22773. Epub 2015 Feb 20.
Obesity has been characterized by alterations in brain structure and function associated with emotion processing and regulation. Particularly, aberrations in food-related reward processing have been frequently demonstrated in obese subjects. However, it remains unclear whether reward-associated functional aberrations in obesity are specific for food-related stimuli or represent a general deficit in reward processing, extending to other stimulus domains. Given the crucial role of rewarding effects in the development of obesity and the ongoing discussion on overlapping neurobiological traits of obesity and psychiatric disorders such as depression and substance-related disorders, this study aimed to investigate the possibility of altered reward processing in obese subjects to occur in the absence of food-related stimuli during a monetary reward condition.
Twenty-nine healthy obese subjects (body mass index >30) and 29 healthy, age-, and sex-matched control subjects of normal weight underwent functional MRI during a frequently used card guessing paradigm. A Group × Condition (win vs. loss) ANOVA was conducted to investigate differences between obese and normal-weight subjects.
We found significant Group × Condition interaction effects in brain areas involved in emotion regulation and reward processing including the insula, the striatum, and the orbitofrontal cortex (OFC). This interaction was predominantly driven by a significant increase in blood oxygenation level dependent (BOLD) response in obese individuals while experiencing reward.
Enhanced neural activation in obesity during reward processing seems to be apparent even in the absence of food-related stimuli and, thus, might point to generalized dysfunctions in reward-related brain circuits in obese individuals.
肥胖的特征是与情绪处理和调节相关的大脑结构和功能发生改变。特别是，肥胖受试者中经常出现与食物相关的奖赏处理异常。然而，肥胖中与奖赏相关的功能异常是特定于食物相关刺激，还是代表奖赏处理的一般缺陷并扩展到其他刺激领域，仍不清楚。鉴于奖赏效应在肥胖发展中的关键作用，以及关于肥胖与精神疾病（如抑郁症和物质相关障碍）重叠神经生物学特征的持续讨论，本研究旨在调查肥胖受试者在金钱奖赏条件下，在没有食物相关刺激的情况下发生奖赏处理改变的可能性。
29名健康肥胖受试者（体重指数>30）和29名年龄、性别匹配的正常体重健康对照受试者，在常用的猜牌范式中接受功能磁共振成像。进行组×条件（赢与输）方差分析，以研究肥胖受试者和正常体重受试者之间的差异。
我们在涉及情绪调节和奖赏处理的脑区，包括岛叶、纹状体和眶额皮质（OFC）中发现了显著的组×条件交互作用效应。这种交互作用主要是由肥胖个体在体验奖赏时，血氧水平依赖（BOLD）反应的显著增加所驱动。
即使在没有食物相关刺激的情况下，肥胖受试者在奖赏处理过程中增强的神经激活似乎也很明显，因此，这可能表明肥胖个体奖赏相关脑回路存在普遍功能障碍。
