Limited research has been conducted to investigate the underlying causal neural mechanisms of substance use disorder by integrating resting-state fMRI data with spectral DCM. Tang et al. [27], employed a limited sample of resting-state fMRI data, consisting of 15 cigarette smokers and 15 nonsmokers, to explore the impact of smoking addiction on the default mode network using spectral DCM. They unveiled the causal and distributed impacts of smoking addiction on four key brain regions (the medial prefrontal cortex, posterior cingulate cortex, left and right inferior parietal lobule) within the default mode network. In another study, a spectral DCM was employed to investigate resting-state causal brain connectivity in individuals with cocaine addiction, using a limited sample size of 15 non-treatment-seeking chronic cocaine smokers and 17 healthy control participants [26]. The findings revealed that the cocaine group exhibited higher EC from the ventral tegmental area to the NACC, hippocampus, and medial frontal cortex compared to the control group. Previous studies have initially explored the causal brain mechanism in the resting state of substance use disorder; however, due to limitations such as small
