Potentially traumatic events and substance use independently but not interactively predict changes in resting state functional connectivity in early adolescence

Potentially traumatic events (PTEs) and substance use (SU) are commonly endorsed in early adolescence, a crucial period for neurodevelopment. Separately, they have been shown to alter within- and between-network connectivity in the three brain networks posited by Menon’s Theory of Psychopathology: the default mode network (DMN), fronto-parietal network (FPN), and salience network (SN). While co-occurring posttraumatic stress disorder (PTSD) and substance use disorder (SUD) in adults show shared neural underpinnings, how co-occurring PTEs and SU in adolescents impact these three functional networks has yet to be examined. We analyzed the effects of PTEs and SU on resting state functional connectivity (rsFC) in 9-15 year old youth from the Adolescent Brain Cognitive Development (ABCD) Study. Fixed effects panel models were fit to assess the effects of PTEs and SU on between-network (FPN-SN rsFC, DMN-SN rsFC, and FPN-DMN rsFC) and within-network (FPN rsFC, SN rsFC, and DMN rsFC) connectivity measured two years apart, across three timepoints. PTEs independently predicted increased FPN-SN and DMN-SN rsFC, as well as increased FPN. Other associations between PTEs and rsFC were explained entirely by age. A significant main effect of SU was found for SN rsFC. Sex*SU negatively and Sex*PTEs*SU positively predicted FPN rsFC. We failed to find evidence for PTEs and SU interactively predicting rsFC, indicating that rsFC changes observed in older adolescents and adults with comorbid PTSD+SUD do not developmentally translate to early adolescents endorsing PTEs+SU. However, we observed independent impacts of PTEs on youth rsFC during early adolescence.