Brain structural and functional changes in childhood and adolescent obesity: a systematic review of MRI studies.

BACKGROUND: Adolescent obesity has emerged as a global public health crisis, with accumulating evidence suggesting that it involves not only peripheral metabolic dysfunction but also significant central nervous system remodeling. Given that childhood and adolescence represent a critical window for neurodevelopment, understanding these alterations is vital for effective intervention. This review aimed to systematically synthesize multimodal magnetic resonance imaging (MRI) findings regarding brain structural and functional changes in children and adolescents with obesity, and its underlying neurobiological mechanisms. METHODS: Following PRISMA guidelines, there were in total 41 high-quality studies encompassing functional MRI, structural MRI, and diffusion tensor imaging modalities involved in this review. RESULTS: Synthesis of the literature reveals a consistent "reward-control" imbalance. Functionally, adolescents with obesity exhibited hyper-responsivity in reward-related regions (e.g., striatum, insula) to food cues, coupled with diminished recruitment of executive control areas (e.g., prefrontal cortex). Structurally, obesity was associated with gray matter atrophy in the prefrontal and cingulate cortices, and lower white matter integrity in tracts connecting these regions (e.g., corpus callosum, uncinate fasciculus). These changes may be associated with a synergy of chronic neuroinflammation, insulin resistance, and dopamine pathway dysregulation, although the cross-sectional nature of most evidence precludes definitive causal inferences. CONCLUSION: Obesity-related brain remodeling constitutes a pathological basis that reinforces maladaptive eating behaviors. Future research should prioritize longitudinal designs and targeted neuro-interventions to mitigate long-term cognitive and metabolic consequences in children and adolescent with obesity.