Elevated BMI impacts brain‐state dynamics within the sensorimotor‐to‐transmodal hierarchy

Abstract Objective Overweight and obesity, as commonly indicated by a higher BMI, are associated with functional alterations in the brain, which may potentially result in cognitive decline and emotional illness. However, the manner in which these detrimental impacts manifest in the brain's dynamic characteristics remains largely unknown. Methods Based on two independent resting‐state functional magnetic resonance imaging data sets (Behavioral‐Brain Research Project of Chinese Personality, n = 1923; Human Connectome Project, n = 998), the current study employed a Hidden Markov model to identify the spatiotemporal features of brain activity states. Subsequently, the study examined the changes in brain‐state dynamics and the corresponding functional outcomes that arise with an increase in BMI. Results Elevated BMI tends to shift the brain's activity states toward a greater emphasis on a specific set of states, i.e., the metastate, that are relevant to the joint activities of sensorimotor systems, making it harder to transfer to the metastate of transmodal systems. These findings were reconfirmed in a longitudinal sample (Behavioral‐Brain Research Project of Chinese Personality, n = 34) that exhibited a significant increase in BMI at follow‐up. Importantly, the alternation of brain‐state dynamics specifically mediated the relationships between BMI and adverse functional outcomes, including cognitive decline and symptoms of mental illness. Conclusions The altered brain‐state dynamics within the sensorimotor‐to‐transmodal hierarchy provide new insights into obesity‐related brain dysfunctions and mental health issues.