Prospective association of adverse childhood experiences and social support with all-cause mortality among young adults in the USA.

Background: This study examined the independent effects of adverse childhood experiences (ACEs) and social support on all-cause mortality among US young adults and assessed whether social support modified the ACEs-mortality association.

Methods: We used data from the National Longitudinal Study of Adolescent to Adult Health, a population-based prospective US cohort. Our study sample included 12 421 children and adolescents aged 11-17 years at baseline (1994-1995) and followed up until 2016-2018. ACEs were assessed from youth and parent responses at baseline. Social support was assessed using a subjective measure of nine items and categorised into high, moderate and low. Weighted multivariable Cox proportional hazards models and Aalen's additive hazards models estimated HRs and hazard differences (HDs) per 10 000 individuals per year.

Results: At baseline, participants' mean age was 15.4 years (SD=1.5), 49% were females and 46% had ≥1 ACEs. 327 deaths (2.6%) occurred during 301 416 person-years of follow-up. High social support was associated with decreased risk of all-cause mortality independent of ACEs after controlling for sociodemographic factors (HR_adjusted: 0.63 (0.42 to 0.93); HD_adjusted: -5.00 (-9.33 to -0.67)). Compared with those without ACEs and high social support, those with ≥1 ACEs and low social support had over two times greater hazards of premature mortality (HR_adjusted: 2.03 (1.45 to 3.49))-equivalent to approximately 9.4 additional deaths per 10 000 people per year (HD_adjusted: 9.41 (2.08 to 16.74)), after adjusting for baseline sociodemographic factors. Stratified analyses showed that ACEs were associated with increased risk of mortality in the low social support group only.

Conclusions: Complementing ACEs prevention efforts with social support interventions could be effective strategies to reduce premature deaths among US young adults.