Increased brain structural–functional coupling in the frontoparietal control network of chronic tobacco smokers

Abstract

Previous studies on chronic smokers have shown altered structural and functional connectivity in large-scale networks; however, both domains have largely been studied in isolation. Here, we estimated structural–functional (SC-FC) coupling in chronic tobacco smokers (47) versus nonsmokers (46) using multimodal magnetic resonance imaging. Structural and functional connectomes were derived, with structural connectivity estimated using SIFT2-weighted tractography and inverse node-volume normalization. SC-FC coupling was computed as the Spearman correlation between SC and FC edge weights for the whole brain and seven Schaefer–Yeo canonical networks. Estimates accounted for interregional distance and were evaluated across densities of 10%–30%. Smokers showed higher coupling in the frontoparietal control network (FPCN) across network densities and Schaefter 246–446 parcellations, but this effect did not survive multiple-comparison correction. Dorsal attention and subcortical effects were also observed at some resolutions, but they were less consistent across parcellations. The FPCN pattern remained directionally consistent in sensitivity analyses including network-specific thresholding and adjustment for motion and global signal, although it did not survive omnibus correction across all tested networks. Within smokers, FPCN coupling was not associated with smoking exposure, nicotine dependence, or trait impulsivity. These results suggest a network-specific alteration in structure–function alignment that warrants further study.