Alcohol use disorder (AUD) presents a perfect theoretical example to illustrate this. AUD is a developmentally dynamic disorder, because initiation of alcohol use and increasing patterns of consumption are necessary precursors to developing symptoms. Initiation happens, for most individuals, in adolescence, while age of onset for AUD diagnosis peaks later in young adulthood (Kessler et al., 2005; Substance Abuse and Mental Health Services Administration, 2014). Twin studies indicate that genetic influences on alcohol use behavior also vary both quantitatively and qualitatively across development (Dick et al., 2007a, Edwards & Kendler, 2013, Kendler et al., 2008, Meyers et al., 2014), with genetic influences being less important in adolescence and increasing in adulthood. It will therefore be beneficial to follow-up genetic association studies in younger, longitudinal cohorts to determine when and through what pathways specific genes are associated with behaviors that move individuals towards or away from developing problems. Mapping these risk pathways could provide information about the most effective developmental stages to implement prevention and intervention efforts. For example, Olfson et al. found that the ADH1B variant associated with adult alcohol
