The goals of these analyses were to identify trajectories of internalizing symptoms from early childhood to early adolescence and to determine whether internalizing trajectories are associated with differential risk of four alcohol-related outcomes in early adolescence. We focused on this period because alcohol experimentation typically begins in early adolescence. While nearly 75% of the sample had stably low levels of internalizing symptoms, the remainder fell into four qualitatively different internalizing symptom trajectories. In general, individuals with elevated symptoms were less likely to engage in at least one of the four alcohol-related outcomes at age 13.8 relative to individuals in the stable low class. This could be due to a causal relationship, where internalizing symptoms protect against alcohol use. A non-causal explanation is also possible, wherein an unobserved shared factor (e.g., genetics or environmental confounders) influences both internalizing symptoms and liability to alcohol use. These mechanisms are not mutually exclusive.
