Iozzo Patricia, Guiducci Letizia, Guzzardi Maria Angela, Pagotto Uberto
Institute of Clinical Physiology, National Research Council (CNR), Pisa, Italy.
Obes Facts. 2012;5(2):155-64. doi: 10.1159/000338328. Epub 2012 Apr 19.
The ongoing epidemics of obesity is one main health concern of the present time. Overeating in some obese individuals shares similarities with the loss of control and compulsive behavior observed in drug-addicted subjects, suggesting that obesity may involve food addiction. Here, we review the contributions provided by the use of positron emission tomography to the current understanding of the cerebral control of obesity and food intake in humans. The available studies have shown that multiple areas in the brain are involved with the reward properties of food, such as prefrontal, orbitofrontal, somatosensory cortices, insula, thalamus, hypothalamus, amygdala, and others. This review summarizes the current evidence, supporting the concepts that i) regions involved in the somatosensory response to food sight, taste, and smell are activated by palatable foods and may be hyperresponsive in obese individuals, ii) areas controlling executive drive seem to overreact to the anticipation of pleasure during cue exposure, and iii) those involved in cognitive control and inhibitory behavior may be resistant to the perception of reward after food exposure in obese subjects. All of these features may stimulate, for different reasons, ingestion of highly palatable and energy-rich foods. Though these same regions are similarly involved in drug abusers and game-addicted individuals, any direct resemblance may be an oversimplification, especially as the heterogeneities between studies and the prevalent exclusion of sensitive groups still limit a coherent interpretation of the findings. Further work is required to comprehensively tackle the multifaceted phenotype of obesity and identify the role of food dependency in its pathophysiology.
当前肥胖症的流行是当今主要的健康问题之一。一些肥胖个体的暴饮暴食与吸毒者所表现出的失控和强迫行为有相似之处，这表明肥胖可能涉及食物成瘾。在此，我们回顾正电子发射断层扫描技术在当前对人类肥胖及食物摄入的大脑控制理解方面所做出的贡献。现有研究表明，大脑中的多个区域与食物的奖赏特性有关，如前额叶、眶额叶、体感皮层、脑岛、丘脑、下丘脑、杏仁核等。本综述总结了当前的证据，支持以下观点：i）参与对食物视觉、味觉和嗅觉的体感反应的区域会被美味食物激活，且在肥胖个体中可能反应过度；ii）控制执行驱动力的区域在提示暴露期间对愉悦预期似乎反应过度；iii）参与认知控制和抑制行为的区域在肥胖个体接触食物后可能对奖赏感知具有抗性。所有这些特征可能因不同原因刺激人们摄入高度可口且能量丰富的食物。尽管这些相同区域在药物滥用者和游戏成瘾个体中也同样涉及，但任何直接的相似性可能都过于简单化，尤其是由于研究之间的异质性以及对敏感群体的普遍排除仍然限制了对研究结果的连贯解释。需要进一步开展工作以全面应对肥胖的多方面表型，并确定食物依赖在其病理生理学中的作用。
