关键词: 儿童, 超重/肥胖, 奖赏, 抑制控制, 双系统

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