Moreover, there was significant level of negative correlation between gray matter volume reduction and changes in the FC in the AUD group especially in the ACC/SMA/mPFC, hippocampus, and hippocampal gyrus (Table 4). It is noteworthy that all the negative correlations between gray matter volume and FC were found only in the ROIs showing loss of gray matter volume (Supplementary Tables 19–24). Jansen et al. (60) suggested that increased FC in areas showing structural impairment is related to compensatory mechanisms for disruption of functional networks. In other words, it utilizes additional activation in FC of the implicated neural areas damaged by alcohol consumption evidenced by volume reduction. Previous studies have reported the effect of long-term consumption of alcohol on GM and WM. In these studies, when alcohol was consumed for a long time, volume reduction was observed in the prefrontal lobe, insular lobe, and anterior cortex, and hyperactivation was observed in these regions (61–64). We found that FC acts in the compensatory mechanism for volume reduction in the core areas of SN and DMN.
