New evidence on the association between endometriosis and traumatic and stressful experiences

The University of Barcelona has participated in an international study that has found new evidence linking traumatic experiences and stressful events with endometriosis, a chronic systemic inflammatory disease characterized by the presence of endometrial-like tissue outside the uterus. They show that the condition appears to be closely linked to trauma involving contact, i.e., those cases where there is direct physical interaction between the victim and the abuser, such as in physical abuse or sexual assault. Through genetic analysis, they have found that this relationship seems to be independent of genetic predisposition to endometriosis. These results, published in the journal JAMA Psychiatry, could be helpful to take into account when diagnosing endometriosis, which affects 190 million women of reproductive age worldwide.

Dora Koller, first author of the article and researcher at the Department of Genetics, Microbiology and Statistics of the UB’s Faculty of Biology, notes that “while psychological trauma has been associated with endometriosis, to date, there has been little information on the role of the type of trauma and genetic predisposition”. “These results challenge established paradigms by uncovering shared genetic mechanisms linking endometriosis with post-traumatic stress disorder and other types of trauma, while providing new insights into how different types of traumatic events are associated with the disease”, says Koller, also researcher at the Department of Psychiatry of Yale School of Medicine.
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The study included the participation of Marina Mitjans, researcher at the same UB department and at the UB Institute of Biomedicine (IBUB), at Sant Joan de Déu Research Institute (IRSJD) and at the Mental Health Networking Biomedical Research Centre (CIBERSAM). Other authors from the University of Bergen (Norway), the Karolinska Institute (Sweden), the University of Oxford (United Kingdom), Harvard T. H Chan School of Public Health, and the Massachusetts General Hospital (United States) also participated in the study.

A study conducted on more than 240,000 women

The study was based on observational and genetic data analyses from 8,276 women with endometriosis and 240,117 controls in the UK Biobank, a biomedical database containing anonymized genetic, lifestyle and health information, as well as biological samples from people in the United Kingdom. “Our study shows that people with endometriosis were more likely to report having experienced certain traumatic events compared to healthy people”, notes the expert. For example, people with endometriosis were 17% more likely to have witnessed a sudden death, 16% more likely to have experienced sexual assault in adulthood and 36% more likely to have received a life-threatening diagnosis.

To explore the connection between different types of trauma, the researchers conducted a latent class analysis, a research tool that unravels hidden clusters in a dataset. “More cases of endometriosis could be linked to emotional, physical and sexual trauma”, the author notes.

Post-traumatic stress disorder and child abuse

The genetic analyses in the study consisted mainly of a genome-wide association study (GWAS) of endometriosis and also an analysis of the interaction between traumatic events and the polygenic risk of endometriosis, an approach that assesses the combined impact of multiple genetic variants on the development of a disease, rather than focusing on a single gene. The results of these analyses have revealed that the disease correlates genetically with several trauma-related conditions, with the strongest evidence being linked to post-traumatic stress disorder and child abuse. Koller notes that “childhood trauma, for example, feeling hated by a family member as a child and being physically abused by the family, was also linked to endometriosis, highlighting the potential role of early adverse experiences in shaping the risk and progression of endometriosis”.

Other genetically inferred relationships included situations related to having someone who could take study participants to the doctor during childhood.  According to the researcher, this would be “especially important” in the case of endometriosis, since having caregivers who ensure access to medical care during this stage of life may influence stress resilience and care-seeking behaviour, reducing the likelihood of under-diagnosis and under-treatment. “People who lack caregiver support may be less likely to defend their health”, she notes.

Mechanisms which do not depend on the genetic predisposition
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The results also show that the relationship between the genetic risk of endometriosis and trauma does not seem to be due to a direct interaction between genes and environment, but would be explained by correlations between genes and environment. That is, for example, people with a certain genetic predisposition may be more likely to experience or remember certain traumatic events, which could influence their risk of developing endometriosis. “Based on the reclassification proposed by Hugh Taylor —co-author of the current study — of endometriosis as a chronic systemic disease with manifestations outside the reproductive tract, our findings highlight how childhood and adult trauma may contribute to the pathogenesis of endometriosis with
mechanisms that appear independent of the genetic predisposition”, she says.

An early diagnosis strategy

The associations identified between endometriosis and traumatic events are consistent with a previous study by the same research team that linked the disease to depression, anxiety and eating disorders. These combined findings highlight the importance of assessing the physical and mental health of patients with endometriosis. “Although the results need to be confirmed in other cohorts, they suggest that we may be able to design early endometriosis screening programmes that consider not only genetic factors, but also a history of physical trauma or other risk factors. This would help to identify and treat the disease more comprehensively and effectively”, the researcher concludes.