Research has shown that experiencing maltreatment in childhood — such as neglect, or physical, psychological, or sexual abuse — can impair healthy brain development. This helps explain why youth who have experienced maltreatment are about three times more likely to develop severe mental disorders in adulthood, such as bipolar disorder or schizophrenia1,2,3. To better understand this phenomenon, scientists are currently exploring a new way to observe the early effects of maltreatment on the brain: by looking through the eyes.
The first signs of the disorder detectable in childhood?
While maltreatment is a major risk factor for the development of mental disorders, other elements also play a role, notably genetic factors. Indeed, children of parents with mental disorders such as schizophrenia or bipolar disorder are 15 to 20 times more likely to develop a disorder similar to that of their parents, compared to children without a family history of mental illness4. Studies conducted in Quebec also show that these children are at risk of exhibiting, from childhood or adolescence, problems similar to those of their parents, although less severe. For example, certain cognitive difficulties observed in people with schizophrenia or bipolar disorder are also found in their children5,6. This suggests that, although these mental disorders usually manifest in early adulthood, their roots may already be visible earlier in development.
Observing the effects of maltreatment on the brain… through the eyes
This may seem surprising, but to better understand how maltreatment can affect the brain, scientists are turning to the retina, the thin membrane at the back of the eye. Why? Because the retina and the brain develop from the same tissue during pregnancy. In a sense, the retina offers a “window into the brain,” accessible in a non-invasive way.
Using a technology called electroretinography, which measures how the eye’s cells respond to flashes of light, scientists can detect signs of dysfunction. For example, studies have shown that adults with psychiatric disorders such as schizophrenia or bipolar disorder display unusual responses to these visual stimuli. The cells in their eyes that detect color (cones) respond more slowly when exposed to light stimuli, and the resulting reaction is weaker than in people without these disorders7. Even more surprising, studies from Quebec have found that the children of these individuals are also at risk of showing abnormal responses8. These results suggest that the retina could provide a way to identify at-risk youth very early, even before the onset of disorders.
Pioneer studies explore the link between maltreatment and retinal anomalies
A study conducted by researchers from Université Laval and Université du Québec à Trois-Rivières, published in 2024 in Biomarkers in Neuropsychiatry9, evaluated the link between different forms of maltreatment and anomalies in retinal responses to electroretinography in children and adolescents at familial risk of psychiatric disorders. The hypothesis was that the effects of maltreatment on brain development could be visible very early in the development of youth at risk of developing a severe mental disorder in adulthood. Moreover, since maltreatment does not affect boys’ and girls’ brains in the same way10,11, the effect was expected to vary by sex.
For this study, a sample of 134 children of a parent with schizophrenia, bipolar disorder or recurrent major depression was recruited. Various types of maltreatment were assessed through interviews with the participants and their parents, as well as through a thorough review of medical records: physical, sexual, and emotional maltreatment; emotional and physical neglect; and exposure to domestic violence between parents.
So, does maltreatment affect the retina?
The results show that maltreatment, in general, is not associated with retinal responses measured by electroretinography. However, in girls, a link was found between physical abuse and longer reaction times to light stimuli. It is currently difficult to understand why physical violence would be especially associated with anomalies in retinal responses. Nevertheless, these results are consistent with those of previous studies. Indeed, some studies show that maltreatment affects boys and girls who have a parent with a severe mental disorder differently12. Other research highlights specific effects of different forms of maltreatment on brain development1.
Another way of studying the eye
Since this first study, the team has employed another technology: optical coherence tomography (OCT). Unlike electroretinography, which measures retinal function, OCT allows visualization of retinal structure by measuring the thickness of its cellular layers. The new results, presented at the Schizophrenia International Research Society congress in April 202513, show that the more types of maltreatment a child has experienced, the thicker certain layers of neurons in the retina become. The researchers believe this is caused by an inflammatory response to stress, leading to swelling in certain neurons. They hypothesize that this swelling is an early sign of potential degeneration of nerve cells14,15.
Why is this important?
These findings are concerning but also full of potential: if confirmed, they could help identify children at higher risk as a result of maltreatment and provide them with sustained support. The goal would be to act quickly to ensure healthy brain development, limit the long-term consequences of maltreatment, and prevent the onset of mental disorders.
In conclusion
Today, the healthcare system often addresses mental disorders only after they have appeared. However, these studies from Quebec suggest new avenues for prevention in high-risk youth. Indeed, these studies are the first in the world to investigate the link between maltreatment and retinal anomalies in humans. Such advances could shed light on the still poorly understood causes of certain mental disorders, such as schizophrenia and bipolar disorder. Most importantly, this research could help identify youth at risk at an early stage, in order to provide better support and prevent the onset of severe mental disorders.
How to cite this article: Dupuis Azizah, M., Deschênes, K., & Berthelot, N. (2025, October 13). The eyes speak volumes: recognizing the impacts of maltreatment on the retina in youth at risk ? TRACE blog. https://natachagodbout.com/en/blog/eyes-speak-volumes-recognizing-impac…
The publication of this article was made possible thanks to our partner, the Interdisciplinary Research Centre on Intimate Relationship Problems and Sexual Abuse (CRIPCAS), and the Fonds de recherche du Québec.
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Ricard, J., Berthelot, N., Fortin-Fabbro, É., Boisvert, M-C., Garon-Bissonnette, J., Arseneault, E., Bureau, A., & Maziade, M. (2024). Childhood trauma and altered response of retinal neurons as an early risk endophenotype of schizophrenia and mood disorder. Biomarkers in Neuropsychiatry, 10. https://doi.org/10.1016/j.bionps.2024.100095
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Berthelot, N., Garon-Bissonnette, J., Jomphe, V., Doucet-Beaupré, H., Bureau, A., & Maziade, M. (2022). Childhood trauma may increase risk of psychosis and mood disorder in genetically high-risk children and adolescents by enhancing the accumulation of risk indicators. Schizophrenia Bulletin Open, 3(1). https://doi.org/10.1093/schizbullopen/sgac017
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Deschênes, K., Berthelot, N., Ricard, J., Arsenault, E., Boisvert, M.-C., Fortin-Fabbro, E., & Maziade, M. (2025, March). Cumulative exposure to childhood trauma would affect the thickness of retinal layers in children at familial risk of schizophrenia, bipolar disorder and major depressive disorder. Poster presentation during the 2025 Annual Congress of the Schizophrenia International Research Society. March 29th – April 2nd 2025, Chicago, USA.
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