One Twin Was Hurt, the Other Was Not. Their Adult Mental Health Diverged. - The New York Times
▻https://www.nytimes.com/2024/03/06/health/one-twin-was-hurt-the-other-was-not-their-adult-mental-health-diverged.html
Protégeons les enfants !!!
Why do twins, who share so many genetic and environmental inputs, diverge as adults in their experience of mental illness? On Wednesday, a team of researchers from the University of Iceland and Karolinska Institutet in Sweden reported new findings on the role played by childhood trauma.
Their study of 25,252 adult twins in Sweden, published in JAMA Psychiatry, found that those who reported one or more trauma in childhood — physical or emotional neglect or abuse, rape, sexual abuse, hate crimes or witnessing domestic violence — were 2.4 times as likely to be diagnosed with a psychiatric illness as those who did not.
If a person reported one or more of these experiences, the odds of being diagnosed with a mental illness climbed sharply, by 52 percent for each additional adverse experience. Among participants who reported three or more adverse experiences, nearly a quarter had a psychiatric diagnosis of depressive disorder, anxiety disorder, substance abuse disorder or stress disorder.
To disentangle the effects of these traumas from genetic or environmental factors, the researchers narrowed the pool to “discordant” pairs, in which only one twin reported maltreatment in childhood. An analysis of 6,852 twins from these discordant pairs found that childhood maltreatment was still linked with adult mental illness, though not as strongly as in the full cohort.
“These findings suggest greater influence than I expected — that is, even after very stringent control of shared genetic and environmental factors, we still observed an association between childhood adversity and poor adult mental health outcomes,” said Hilda Bjork Danielsdottir, a doctoral candidate at the University of Iceland and the study’s first author.
A twin who reported maltreatment was 1.2 times as likely to suffer from a mental illness as the unaffected twin in identical twin pairs, and 1.7 times as likely in fraternal twin pairs. This effect was especially pronounced among subjects who reported experiencing sexual abuse, rape and physical neglect.
For decades, researchers have been accumulating evidence that links child abuse and maltreatment to illnesses later in life. A landmark 1998 study of 9,508 adults found a direct correlation between childhood maltreatment and heart disease, cancer, lung disease and depression, often linked by behavior like smoking and alcohol use.
By ruling out the role of genetic factors, the new findings should help dispel any remaining doubt that childhood maltreatment leads to worse mental health in adulthood, said Mark Bellis, a professor of public health at Liverpool John Moores University in Britain, who was not involved in the study.
The findings add to “the increasingly irrefutable evidence that it is going to cost us all a lot less if we invest in tackling” abuse and neglect of children now, he added, rather than “continuing to pay for the epidemic levels of harm” they cause downstream.