Linking Childhood Adversity to Adult Mental Health

Summary: Researchers delved into how adverse childhood experiences contribute to the risk of psychiatric illness in adulthood, leveraging data from over 25,000 twins in the Swedish Twin Registry. The study uncovers a dose-response relationship between childhood adversity and later mental health problems, while also highlighting the significant role of genetic and environmental factors within families.

By analyzing twins with differing experiences of abuse but shared family backgrounds, the research provides nuanced insights into the interplay between direct abuse effects and inherited or environmental influences. This study underscores the importance of family-wide health interventions to mitigate the long-term mental health risks associated with childhood adversities.

Key Facts:

1. Twin Study Design Reveals Complexity: The use of a twin study allowed researchers to distinguish between the impacts of direct abuse and those attributable to genetic and environmental factors shared within families.
2. Dose-Response Relationship: The research confirmed a clear correlation where increasing levels of childhood adversity are linked to higher risks of developing psychiatric disorders in adulthood.
3. Significance of Sexual Abuse: Sexual abuse and rape in childhood, especially when combined with three or more types of adverse experiences, were found to be most strongly associated with future mental health issues.

Source: Karolinska Institute

A research team has examined the link between adverse childhood experiences and the risk of mental health problems later in life, according to a study in JAMA Psychiatry.

The researchers from Karolinska Institutet and University of Iceland have found that the risk of suffering from mental illness later in life among those experiencing significant adversity in childhood can be partly explained by factors shared by family members, such as genetics and environment.

Several previous studies have shown that people who have experienced various types of adverse childhood experiences have a higher risk of suffering from psychiatric illness later in life.

Now, a new study from Karolinska Institutet, using a special type of twin research design, can confirm the link, show a clear dose-response relationship and at the same time broaden the picture.

The researchers can now show that there are also significant genetic and environmental factors that play a role and contribute to mental illness.

The researchers used three different cohorts of the Swedish Twin Registry, comprising over 25,000 individuals. The twins’ responded to a large web-based questionnaire and answered questions about different types of adverse childhood experiences including family violence, emotional abuse or neglect, physical neglect, physical abuse, sexual abuse, rape and hate crime. In addition, information about adult psychiatric disorders was obtained from the Swedish Patient Registry.  

“These are of course very difficult questions to answer, but this is the best data source we have access to,” says Hilda Björk Daníelsdóttir, a doctoral student at the University of Iceland and visiting doctoral student at the Institute of Environmental Medicine at Karolinska Institutet and the study’s first author.

By identifying twin pairs who reported different experiences of abuse while growing up in the same family and then following those who later received a psychiatric diagnosis, the researchers have been able to sort out how much of the increased risk is due to the abuse itself and how much is due to genetics and environment.

“Most previous studies on the mental health effects of childhood adversity have not been able to take these things into account. Now we can show that the increased risk of mental health problems after adverse childhood experiences can be partly explained by factors shared by family members, such as genetic factors or factors in the childhood environment,” says Hilda Björk Daníelsdóttir.

She argues that this finding should therefore lead to health care interventions addressing risk factors within the whole family, not just the affected child or children.

The more different types of childhood adversities individuals experienced, the higher the risk was of receiving a psychiatric diagnosis later in life. The researchers can also show that sexual abuse and rape in childhood as well as having experienced three or more types of adversities were the experiences most strongly linked to future mental health problems. This is something that is also important knowledge when treating vulnerable children and their families.

“I hope that our study can raise awareness of childhood circumstances as possible causes of psychiatric disorders in adulthood and how to best address them,’ says Hilda Björk Daníelsdóttir.

Funding: The research was funded by the European Research Council, the Icelandic Research Center and the EU’s Horizon 2020.

About this mental health and neurodevelopment research news

Author: Hilda Björk DaníelsdóttirSource: Karolinska InstituteContact: Hilda Björk Daníelsdóttir – Karolinska InstituteImage: The image is credited to Neuroscience News

Original Research: Open access.“Adverse Childhood Experience and Adult Mental Health Outcomes” by Hilda Björk Daníelsdóttir et al. JAMA Psychiatry

Abstract

Adverse Childhood Experience and Adult Mental Health Outcomes

Importance  

Exposure to adverse childhood experiences (ACEs) has consistently been associated with multiple negative mental health outcomes extending into adulthood. However, given that ACEs and psychiatric disorders cluster within families, it remains to be comprehensively assessed to what extent familial confounding contributes to associations between ACEs and clinically confirmed adult psychiatric disorders.

Objective  

To investigate whether associations between ACEs and adult mental health outcomes remain after adjusting for familial (genetic and environmental) confounding.

Design, Setting, and Participants  

This Swedish twin cohort study used a discordant twin pair design based on monozygotic (MZ) and dizygotic (DZ) twins. A total of 25 252 adult twins (aged 18-47 years) from the Swedish Twin Registry born between 1959 and 1998 were followed up from age 19 years until 2016, with a maximum follow-up time of 39 years. Data were analyzed from April 2022 to November 2023.

Exposures  

A total of 7 ACEs, including family violence, emotional abuse or neglect, physical neglect, physical abuse, sexual abuse, rape, and hate crime, were assessed with items from the Life Stressor Checklist-Revised in a web-based survey.

Main Outcomes and Measures  

Adult (ages >18 years) clinical diagnosis of psychiatric disorders (ie, depressive, anxiety, alcohol or drug misuse, or stress-related disorders) were obtained from the Swedish National Patient Register.

Results  

Of 25 252 twins included in the study (15 038 female [59.6%]; mean [SD] age at ACE assessment, 29.9 [8.7] years), 9751 individuals (38.6%) reported exposure to at least 1 ACE. A greater number of ACEs was associated with increased odds of any psychiatric disorder in the full cohort (odds ratio [OR] per additional ACE, 1.52; 95% CI, 1.48-1.57). The association remained but ORs per additional ACE were attenuated in DZ (1.29; 95% CI, 1.14-1.47) and MZ (1.20; 95% CI, 1.02-1.40) twin pairs. Individuals who were exposed to sexual abuse compared with those who were not exposed had increased odds of any clinically confirmed psychiatric disorder in all comparisons: full cohort (OR, 3.09; 95% CI, 2.68-3.56), DZ twin pairs (OR, 2.10; 95% CI, 1.33-3.32), and MZ twin pairs (1.80; 95% CI, 1.04-3.11).

Conclusions and relevance  

This study found that associations between ACEs and adult mental health outcomes remained after controlling for shared genetic and environmental factors, which was particularly evident after multiple ACEs or sexual abuse. These findings suggest that targeted interventions may be associated with reduced risks of future psychopathology.