Association of Long‐Term Trajectories in Obesity Indices With Neuroimaging Metrics and Cognition: A Population‐Based Study

Objective Accurate assessment of gradual age‐related weight gain, a common phenomenon, is crucial for identifying brain health risks. This study investigated the associations between long‐term trajectories in obesity indices and brain structure and cognition. Methods This study included 1114 participants from the Kailuan cohort with ≥ 3 follow‐up visits during 2006–2018. The trajectories of body mass index (BMI), waist circumference (WC), and waist‐to‐hip ratio (WHR) were identified using group‐based trajectory modelling. Cognition was assessed using the Montreal Cognitive Assessment. Associations of trajectories in obesity indices with neuroimaging metrics and cognition were examined using generalized linear models. Mediation analyses were performed to assess the associations between trajectories in obesity indices, neuroimaging metrics and cognition. Results Participants with high‐stable WC trajectory were associated with lower grey matter volume (GMV) ( β = −0.331; 95% CI: −0.522 to −0.139) and higher white‐matter hyperintensity (WMH) ( β = 0.423; 95% CI: 0.166 to 0.680). The high‐stable BMI trajectory showed similar associations. The high‐stable WC and WHR trajectories were associated with lower cognition ( β = −0.909; 95% CI: −1.701 to −0.116; β = −0.543; 95% CI: −1.034 to −0.052). GMV atrophy and high WMH statistically partially explained the association between high‐stable WC and WHR trajectories and cognitive decline. Conclusions Persistent central obesity is associated with adverse brain structural changes, and WC and WHR trajectories are associated with cognitive decline. Preventing persistent central obesity may help preserve brain health and cognition.