These findings have several implications for prevention science. First, they suggest that family based prevention programs like SAAF may have links to beneficial changes in the biological underpinnings of attachment, indicating that beneficial effects of some prevention programs may become biologically embedded and exert effects that will not be apparent until later in life. Supporting this view, supplemental analyses indicated that methylation of OXTR predicted subsequent change in risky behavior (See supplemental table S4) even after controlling for SAAF, substance use, and other control variables, encouraging further investigation of OXTR methylation as a factor in future resilience. Second, the results suggest that lower OXTR methylation may depend on successful delay of substance use initiation, particularly among those who are more vulnerable. Future research will be necessary to replicate this effect and to examine the time course of the changes in methylation to see if they may be useful as rapid indicators of program success. To the extent that other biomarkers of resilience can be identified, it will also be useful to investigate the role of SAAF in calibration of other
