Twin study: Adverse childhood experiences linked to poor adult mental health outcomes

Adverse childhood experiences (ACEs) are associated with depression, anxiety, substance use disorder, and stress-related disorders in adulthood, a twin cohort study has shown.

“Exposure to ACEs has consistently been associated with multiple negative mental health outcomes extending into adulthood,” wrote the researchers. “However, given that ACEs and psychiatric disorders cluster within families, the extent of contribution of familial [ie, genetic and environmental risk factors] confounding to associations between ACEs and clinically confirmed adult psychiatric disorders remains to be comprehensively assessed.”

“The discordant twin pair design [based on monozygotic and dizygotic twins] provides a unique opportunity to adjust for unmeasured genetic and early environmental confounders,” pointed out the researchers. Therefore, they collected data from the Swedish Twin Registry involving 25,252 adult twins born in 1959─1998 (mean age at ACE assessment, 29.9 years; female, 59.6 percent), who were followed up from age 19 years until 2016, with a maximum follow-up period of 39 years. [JAMA Psychiatry 2024;doi:10.1001/jamapsychiatry.2024.0039]

The assessed ACEs included family violence, emotional abuse or neglect, physical neglect, physical abuse, sexual abuse, rape, and hate crime. A total of 9,751 individuals (38.6 percent) reported exposure to ≥1 ACE and 2,379 individuals (9.4 percent) received a clinical diagnosis of psychiatric disorder.

In the full cohort, individuals who experienced ≥1 ACE had a significantly greater risk of developing any adult psychiatric disorder (odds ratio [OR], 2.39; 95 percent confidence interval [CI], 2.19─2.60) vs those without ACE exposure. Results were consistent in all psychiatric disorder subtypes, including anxiety (OR, 1.54; 95 percent CI, 1.48─1.60), depression (OR, 1.56; 95 percent CI, 1.50─1.62), stress-related disorders (OR, 1.56; 95 percent CI, 1.49─1.63), and substance use disorder (OR, 1.60; 95 percent CI, 1.52─1.69).

“Notably, exposure to multiple ACEs sharply increased the odds of any psychiatric disorder in a dose-dependent manner [OR for each additional ACE, 1.52; 95 percent CI, 1.48─1.57],” noted the researchers.

However, discordant twin-pair analyses revealed 57.5 percent and 39.1 percent attenuated ORs in monozygotic and dizygotic twins, respectively. “The attenuation of effect sizes from the full cohort to monozygotic and dizygotic twins indicated that environmental [eg, parental style, socioeconomic disadvantage] and genetic factors may have contributed to the association between ACEs and adult mental health outcomes,” explained the researchers.

“Of note, the associations remained evident after adjustment for shared genetic and environmental factors, with particularly large increases in odds after exposure to multiple ACEs or sexual abuse,” highlighted the researchers.

Additionally, a recent cohort study in 1,024 young adults (mean age, 22.4 years; female, 51.1 percent) revealed that positive nonparental adult support and parent-child relationships during childhood were associated with lower odds of depression (adjusted OR, 0.84; 95 percent CI, 0.73─0.97) and generalized anxiety disorder (adjusted OR, 0.81; 95 percent CI, 0.69─0.95) in young adulthood. [JAMA Psychiatry 2023;doi:10.1001/jamapsychiatry.2023.4900]

“In addition to promoting positive relationships with adults during childhood, other interventions targeting ACEs, including primary prevention and enhanced access to evidence-based trauma therapies, may be associated with reduced risk of poor future mental outcomes in adulthood,” suggested the researchers.