Multiple risk behaviour in adolescence is associated with substantial adverse health and social outcomes in early adulthood: Findings from a prospective birth cohort study.

Adolescents' engage in new behaviours such as substance use and change others, such as reducing physical activity. Risks to health from these tend to be considered separately. We examined the association between multiple risk behaviours at age 16 years and outcomes in early adulthood. 5591 young people enrolled in the Avon Longitudinal Study of Parents and Children provided data on at least one of seven adverse outcomes at age ~18 years. We used logistic regression to examine associations between total number of risk behaviours and rates of depression, anxiety, problem gambling, getting into trouble with the police, harmful drinking, obesity and not in education, employment or training (NEET) at age 18 years. We found strong associations between multiple risk behaviours and all seven adverse outcomes. For each additional risk behaviour engaged in the odds of harmful drinking increased by OR = 1.58[95%CI:1.48,1.69], getting into trouble with the police OR = 1.49[95%CI:1.42,1.57], having depression OR = 1.24[95%CI:1.17,1.31], problem gambling OR = 1.20[95%CI:1.13,1.27], NEET OR = 1.19[95%CI:1.11,1.29], anxiety OR = 1.18[95%CI:1.12,1.24] and obesity OR = 1.09[95%CI:1.03,1.15]. Neither adjustment for sex, parental socio-economic position and maternal risk behaviours, nor confining analyses to adolescents with no previous presentation of these adverse outcomes, resulted in any notable reductions in the odds ratios. Investment in interventions and environments that effectively prevent multiple risk behaviour is likely to improve a range of health outcomes in young adults.