Developmental Variation in the Association Between Substance Use and Firearm Aggression From Adolescence to Emerging Adulthood: A Time-Varying Effect Modeling Approach.

OBJECTIVE: Firearm assault injury is a leading cause of death among adolescents and emerging adults. Less is known about how firearm aggression (i.e., using a firearm to threaten or injure someone) varies developmentally during this life stage, and how demographic factors and substance use contribute to its trajectory. METHOD: Participants were 599 individuals aged 16 to 25 who sought emergency care in Flint, Michigan, and reported past-six-month drug use. An accelerated cohort design was used to organize the data by respondents' age in quarter-year increments at the time of measurement; each participant contributed up to five repeated assessments. Time-varying effect models (TVEM) were used to examine how sociodemographic characteristics and alcohol, cigarette, and cannabis use frequencies were associated with the likelihood of firearm aggression across age. RESULTS: The probability of firearm aggression peaked at the onset of emerging adulthood (ages 18-20). Being male was positively associated with firearm aggression during adolescence into emerging adulthood. Alcohol use frequency was also positively associated with firearm aggression in adolescence, with effects diminished by emerging adulthood. Cannabis and cigarette use frequencies, as well as race, parental education, and public assistance, were not associated with firearm aggression across age. CONCLUSIONS: Firearm aggression was most prevalent as youth transitioned into emerging adulthood from adolescence, particularly among males and youth who used alcohol more frequently. This may reflect a period of developmental vulnerability involving ongoing maturation in self-regulation and emerging norms around masculinity, particularly among youth in under-resourced communities where community violence is prevalent.