substance use over time. Alternatively, stronger associations in adolescence may reflect the imbalance in arousal and regulation that characterizes the developing adolescent brain: pubertal maturation increases emotional arousal, sensation-seeking, and reward orientation, yet adolescents do not have fully formed executive functioning to help regulate and inhibit behavior (Crews et al., 2007; Guerri and Pascual, 2010; Steinberg, 2005). In the absence of well-developed executive functioning, adolescents may have fewer cognitive and emotional resources to cope with life stressors, so they may be more likely than individuals at other ages to engage in substance use to relieve depressive symptoms (e.g., self-medicate). Furthermore, social acceptance and peer norms are extremely salient during adolescence (Christie and Viner 2005; Eisenberg et al., 2014); youth who use substances due to these external social motivations may experience greater cognitive dissonance and distress, potentially heightening their risk for depressive symptoms. Finally, neuroscience research has shown heavy substance use to be associated with decreased neural plasticity and structural abnormalities in the brain, which may result in both short- and long-term behavioral impairments. Specifically, youth with an alcohol use disorder show structural deficits in the hippocampus and prefrontal cortex compared to youth without an alcohol use disorder (De Bellis et
