All but 2 of the OUD subjects in this study were current users according to their DSM-5 diagnosis, and therefore this study was unable to compare former opioid users with current opioid users. Future studies should include subjects with past OUD to compare the effects of former vs. current OUD on network connectivity. On the other hand, the time since last opioid use was analyzed in the present study and showed no significant effects on functional connectivity in the networks analyzed. We also compared OUD subjects who were UDS positive for buprenorphine or methadone with OUD subjects who were UDS positive for only illicit opioids and found no statistically significant differences between the two subgroups. However, this subgroup analysis was also underpowered because of small subgroup sample size.
