To that end, we recommend the following routes for future work. Carefully conducted, large-scale longitudinal studies that evaluate youth prior to drinking onset, are critical for deconstructing the ‘chicken or the egg’ issue (e.g., Jacobus & Tapert, 2013; Lisdahl et al., 2013a; Spear, 2014; Welch et al., 2013). In addition to longitudinal designs, future studies would benefit from including larger samples, other measures of substance use (e.g., biological markers of alcohol use along with self-report), a broader range of substance use, and longer follow-up periods. While it is not ethically possible to randomize youth to receive social disadvantage or maternal alcohol use, or even to use alcohol itself, it might be worthwhile to compare youth who only use alcohol versus those who are polysubstance using, to determine how different patterns of substance use impact the developing brain.
