Psychosis has long resisted simple explanations. Its emergence is shaped by a shifting combination of inherited biology, developmental experience and environmental stress, yet many studies have examined these forces separately. A new analysis from the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions, or EU-GEI, brings two major lines of evidence together: polygenic scores that capture biological pathways and exposure to traumatic experiences. Published in Translational Psychiatry, the study by Giulia Trotta, Ines Austin-Zimmerman, Elena Spinazzola and colleagues explores how genetic vulnerability and trauma may be interpreted within the same framework.
The work addresses a central problem in psychiatric genetics. Psychosis is not caused by a single gene, and no individual genetic variant can reliably predict who will develop a psychotic disorder. Instead, risk is distributed across thousands of DNA variants, each typically exerting a very small influence. A polygenic score adds these effects into a single statistical measure, estimating a person’s inherited liability for a trait. In conventional analyses, the variants may be combined into a broad score for schizophrenia or psychosis. The EU-GEI study takes a more biologically focused approach by grouping variants according to the pathways in which they participate.
Biological pathway polygenic scores are designed to ask a more precise question: which cellular systems may be contributing to vulnerability? Pathways can involve processes such as immune signaling, synaptic communication, neuronal development or regulation of gene activity. By aggregating genetic signals within these functional networks, researchers can examine whether particular biological mechanisms are more strongly related to psychosis than an undifferentiated genome-wide score would suggest. This does not mean that a pathway score identifies a single cause. Rather, it provides a way to connect statistical genetic associations with plausible biological processes.
The second component of the analysis is trauma. Experiences such as childhood adversity, abuse, neglect or other severe stressors have repeatedly been associated with an increased probability of psychotic experiences and psychotic disorders. Trauma, however, is not a deterministic trigger. Many people exposed to adversity do not develop psychosis, while some people who experience psychosis report little or no trauma. This variation is precisely why researchers are investigating whether environmental exposures operate differently depending on a person’s underlying biological susceptibility.
The EU-GEI project provides a valuable setting for this investigation because it was created to study how genetic and environmental factors combine across different populations. Rather than treating psychosis as the result of either nature or nurture, the research framework considers their possible interaction. In statistical terms, an interaction occurs when the relationship between one factor and an outcome changes according to the level of another factor. In this context, the analysis examines whether trauma-related associations with psychosis vary across levels of pathway-based genetic liability, and whether genetic associations are altered by trauma exposure.
This approach is technically important because the relationship between genes and environment is rarely linear or uniform. A genetic predisposition may increase sensitivity to stress, influence how the brain responds to adversity or affect developmental processes that shape later vulnerability. At the same time, trauma can alter biological systems involved in inflammation, hormone regulation, neural connectivity and learning. These changes may overlap with the same pathways implicated by genetic studies. Integrating the two sources of information therefore offers a more realistic model of psychosis than analyzing genetic risk and life experience in isolation.
The study’s findings contribute to an expanding movement toward mechanistic psychiatry, in which researchers seek to identify measurable biological systems beneath broad diagnostic categories. Psychosis includes a wide range of symptoms and trajectories, from hallucinations and delusions to cognitive and motivational changes. Two people with the same diagnosis may have very different combinations of risk factors. Pathway-level analysis may eventually help explain some of this heterogeneity by identifying biologically distinct profiles, although the current evidence remains a population-level research tool rather than a clinical diagnostic test.
The researchers’ work also highlights the limits that must accompany enthusiasm about genetic prediction. Polygenic scores are statistical estimates developed from reference populations, and their accuracy can vary across ancestries and datasets. They do not determine an individual’s future, and they cannot capture the full complexity of development, social context, protective relationships or access to care. Trauma measurements can also be affected by recall, timing and differences in how experiences are defined. These factors make replication essential before pathway scores or combined genetic-environmental models could be considered for routine clinical use.
For now, the EU-GEI analysis offers a scientifically significant shift in perspective: psychosis risk is best understood as a dynamic system in which biological pathways and lived experience may converge. The findings do not reduce mental illness to genes, nor do they frame trauma as an unavoidable cause. Instead, they support a model in which vulnerability emerges through multiple interacting processes. As larger and more diverse studies build on this work, integrating pathway-based genetics with environmental data could help researchers identify mechanisms for prevention and develop treatments that are better matched to the biology and life histories of individual patients.
Subject of Research: The interaction between biological pathway polygenic scores, trauma exposure and psychosis risk.
Article Title: Integrating biological pathway polygenic scores and trauma in psychosis: findings from the EU-GEI study.
Article References: Trotta, G., Austin-Zimmerman, I., Spinazzola, E. et al. “Integrating biological pathway polygenic scores and trauma in psychosis: findings from the EU-GEI study.” Translational Psychiatry (2026). https://doi.org/10.1038/s41398-026-04317-7
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41398-026-04317-7
Keywords: psychosis, trauma, polygenic scores, biological pathways, psychiatric genetics, gene-environment interaction, EU-GEI, schizophrenia research, mental health, precision psychiatry
