Abstract: The latest data from the World Health Organization shows that there are more than 1 billion obese people in the world, of which 340 million are teenagers and 39 million are children. In China, the overweight and obesity rate among children and adolescents aged 6 to 17 years is as high as 19 percent, and the overweight and obesity rate among children under 6 years of age is more than 10 percent. Childhood obesity is associated with serious physical, psychological and cognitive problems, including cardiovascular disease, sleep disorders, diabetes, increased risk of suicide, and impaired attention, social skills and executive function, and requires urgent attention from society as a whole.
Obesity is a chronic metabolic disease that is harmful to health because energy intake exceeds energy expenditure, leading to excessive accumulation of body fat. The onset and development of childhood obesity is influenced by a combination of genetics, environment, eating behaviors, and motion, and human brain plays an important role in the process of overeating that leads to obesity. The brain's control of eating involves several brain systems, including the homeostatic system, the attention system, the emotion and memory systems, and the cognitive control and reward systems. These neural circuits interact to control energy intake and expenditure. In the study of obesity-brain association, researchers have focused more on the role of the reward system and the inhibitory control system (cognitive control) and referred to these two systems as the dual brain systems. Previous studies have focused on the association between single brain system (reward sensitivity or inhibitory control) and childhood obesity, while there is a lack of systematic exploration of the interactions of dual brain systems. Examining the interactions of multiple brain regions can help to identify susceptible populations at risk for obesity more accurately. Taken together, the available evidence suggests that children with overweight or obese (OW/OB) show extensive structural differences in the brain reward and inhibitory control systems compared with normal ones, such as larger volume of the nucleus accumbens and amygdala, thinner orbitofrontal cortex, and reduced gray matter volume and cortical thickness in the prefrontal cortex and anterior cingulate gyrus. They also have lower functional connectivity in reward networks (e.g., the striatum-orbitofrontal cortex) and control networks compared to typically developing children. In addition, altered functional connectivity between reward and control-related networks was observed in children with a higher BMI. However, no associations between childhood obesity and their brain activity have been found in reward and inhibitory control-related tasks. Future studies may consider exploring the neural mechanisms of childhood obesity in depth in the following aspects. (1) Researchers could focus on the unique role of causal interactions between the brain's reward and inhibition control systems in childhood obesity, and further reveal whether and how the basis/mechanisms of these neural interactions are involved in the onset and maintenance of childhood obesity. (2) A dynamic developmental perspective is needed to explore the bidirectional relationship between changes in children's BMI and changes in brain structure and function. (3) Applying machine learning modeling in a large sample of children to explore robust predictors of childhood obesity to identify individuals at high risk for increased risk of overweight and obesity. (4) Considering the important role of genetic variation in morphological differences in the cerebral cortex and eating behavior. In general, more large-scale longitudinal studies are needed in the future, beginning in early childhood, with multiple repeated measures of obesity, brain function and structure, and cognition, combining resting-state and task-state designs, and adequately modelled over time, to gain insight into the potential differences in neural and behavioral processes across developmental stages.

Key words: children, overweight/obesity, reward, inhibitory control, dual system

摘要： 肥胖已成为严重的全球健康问题。目前我国6至17岁儿童青少年超重肥胖率高达19%。大脑奖赏系统和抑制控制系统（双系统）对儿童肥胖的重要作用已经得到了实证研究的支持。超重/肥胖儿童在双系统结构和功能上表现出异常,尤其是伏隔核体积增大、眶额叶皮层变薄,前额叶灰质体积减小,在奖赏网络、控制网络中的功能连通性较低。可见,超重/肥胖儿童表现出奖赏加工和抑制控制的功能异常,这与不健康进食行为有关,进而加剧了肥胖风险。当前研究多聚焦于大脑单系统在儿童肥胖发生发展过程中的作用,缺少对双系统相互作用的系统探究,而考察多个关键脑区/系统间的交互关系有助于更准确地识别出高风险儿童。未来需要更多大型纵向研究,结合认知行为测量,全面多维地探明儿童肥胖与大脑发育的动态发展机制,以期为儿童肥胖的早期预防和干预提供依据和支持。

关键词: 儿童, 超重/肥胖, 奖赏, 抑制控制, 双系统