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Child Psychiatrist /Adult Psychiatrist

Childhood Adversity Robustly Linked to Adult Mental Illness

Adverse childhood experiences (ACEs) are associated with a significantly increased risk for adult depressive, anxiety, and stress-related disorders, new data from a large registry study of twins showed.

Adult Mental Illness

Researchers found that each additional adverse event placed children at a 52% greater risk for a psychiatric disorder as an adult, with sexual abuse associated with the greatest risk.

The findings showed that the association held even after controlling for shared genetic and environmental factors.

The results suggested that "interventions targeting ACEs, including primary prevention and enhanced access to evidence-based trauma therapies to individuals who experienced ACEs, may be associated with reduced risk of future psychopathology," the investigators, with first author Hilda Björk Daníelsdóttir, MSc, of the University of Iceland, Reykjavik, Iceland, wrote.

The findings were published online on March 6 in JAMA Psychiatry.

Dose-Dependent Effect

Previous research has shown a robust link between childhood abuse and an increased risk for psychiatric disorders in adulthood, but evidence of this association in studies that adjust for familial confounding is "completely lacking," the investigators wrote.

To learn more about how genetic factors may affect the relationship between ACEs and later psychiatric diagnoses, the investigators used data from the nationwide Swedish Twin Registry, which includes data on more than 25,000 identical and nonidentical twins.

The twin registry is linked to the Swedish National Patient Registry, which includes information on inpatient or outpatient psychiatric diagnoses after age 19.

The twins responded to a large web-based questionnaire about past-week depressive symptoms as a measure of current mental health and distinct types of ACEs including family violence, emotional abuse or neglect, physical neglect, physical abuse, sexual abuse, rape, and hate crime.

Three birth cohorts from the twin registry were surveyed between 2005 and 2016 and followed up in the national registry from age 19 until the end of 2016.

Among the sample of 25,000 twin pairs (15,000 female; mean age at assessment, 29 years), 9750 (39%) participants reported exposure to at least one ACE, while 2000 (8%) reported exposure to three or more ACEs. Most respondents — 61% — reported no ACE exposure.

More than 2300 participants received a psychiatric diagnosis as an adult. The incidence of any psychiatric disorder increased from 503 individuals (6.4%) among participants without any ACEs to 993 individuals (24.6%) among those reporting three or more.

At the cohort level, a greater number of ACEs was associated with increased odds of any psychiatric disorder in a dose-dependent manner, the investigators noted (odds ratio [OR], 1.52; 95% CI, 1.48-1.57).

Untangling Genes and Environment

To determine how much of the increased risk for adult mental illness is due to ACEs and how much can be attributed to genetics and environment, the researchers focused on twin pairs where one had exposure to one type of ACEs and the other did not. This analysis revealed that the association remained but was attenuated. In identical twins, the effect of each ACE raised the odds of having a psychiatric condition by 20% (1.20; 95% CI, 1.02-1.40), and for nonidentical twins, the odds increased by 29% (1.29; 95% CI, 1.14-1.47).

The weakening of the risk "suggests that familial confounding contributed to the association between ACEs and adult mental health outcomes," the authors wrote.

Of all the ACEs, sexual abuse carried the highest risk for adult psychiatric disorders. Children who were exposed to sexual abuse, compared with those who were not, had up to a 200% higher risk for any psychiatric disorder in the following comparisons: Full cohort (OR, 3.09; 95% CI, 2.68-3.56), dizygotic twin pairs (OR, 2.10; 95% CI, 1.33-3.32), and monozygotic twin pairs (1.80; 95% CI, 1.04-3.11).

"Our results demonstrated that familial factors contributed to a lesser extent to the association between sexual abuse and adult psychiatric disorders," the authors wrote.

One major limitation of the study was that ACEs were based on retrospective report and thus may be subject to recall bias. Also, the findings cannot be generalized to other countries or cultures.

The study was funded by the European Research Council, the Icelandic Center for Research, and the European Union Horizon 2020. Disclosures are noted in the original article.

Note: This article originally appeared on Medscape

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