in their study [28]. In our sample, when conducting this check, there was no statistically significant correlation between mFD and functional connectivity in any of the 4 networks analyzed. Education and NU were also not statistically significantly related to the functional connectivity of any of the 4 networks analyzed. Another limitation is that 16 of the OUD subjects were tobacco users while none of our HC subjects were tobacco users. Tobacco-using OUD subjects did not statistically significantly differ from non-tobacco-using OUD subjects in functional connectivity of any of the 4 networks analyzed, although this analysis was underpowered. Future studies comparing OUD to HC should aim to balance subject groups for years of education attained, NU, and tobacco use. Due to the small sample size, difference in baseline demographic variables between OUD and HC subjects, and heterogeneity in drug use and treatment status in the OUD subjects, our results should be interpreted with caution and treated as preliminary. Furthermore, our results do not provide evidence regarding any specific behavioral correlates of the weaker LECN resting state fMRI functional connectivity in OUD relative to HC. Future studies should examine the addiction-related behavioral associations of LECN functional connectivity differences between OUD and HC.
