DMN functional connectivity did not differ between groups. The lack of a significant difference in DMN functional connectivity may be related to previous findings suggesting that DMN functional connectivity may be influenced by recent drug use, although recency of last opioid use was unrelated to DMN functional connectivity in our post-hoc analysis [5]. It is also possible that different sub-systems and sub-regions of the DMN may be differentially affected by chronic drug use [3]. Our findings also showed that SN and RECN functional connectivity did not differ between OUD and HC, and we were unable to find previous published studies using ICA that compared OUD and HC within these networks. Our results do not support any statistically significant differences in functional connectivity of any of the 4 networks examined between severe OUD and mild or moderate OUD subgroups, although this subgroup analysis was underpowered due to small subgroup sample size.
