Summary: New research indicates that congenital or very early cortical blindness—blindness from birth or shortly thereafter—appears to protect against the development of schizophrenia. Investigators suggest that compensatory cortical reorganization and brain plasticity may underlie this protective effect.
Source: University of Western Australia.
A recent whole-population study by The University of Western Australia provides strong evidence that congenital or early cortical blindness is associated with a markedly reduced risk of schizophrenia.
The finding is notable because schizophrenia is a complex psychiatric disorder whose precise causes remain unclear despite decades of research. Typical symptoms include a loss of contact with reality, auditory hallucinations, and, in some cases, visual hallucinations. Discovering factors that reduce risk could shed light on the brain mechanisms involved and open new paths for prevention or early intervention.
The research team analyzed health register data collected in Western Australia for births between 1980 and 2001, covering nearly half a million people. Among the cohort, none of the individuals identified with congenital or early cortical blindness went on to develop schizophrenia. The study also found that these individuals did not develop other psychotic illnesses included in the analysis.
Lead author Professor Vera Morgan of the UWA Neuropsychiatric Epidemiology Research Unit noted the striking absence of schizophrenia and related psychotic disorders among people with congenital or early cortical blindness, and emphasized that the result warrants further investigation.
Professor Morgan and colleagues propose that brain plasticity—the capacity of the developing brain to reorganize and form new neural connections—may account for the protective effect. In cases of congenital or very early cortical blindness, regions of the visual cortex and related networks appear to reorganize to support other functions. This compensatory cortical reorganisation may strengthen certain cognitive or perceptual processes that are typically impaired in schizophrenia.
“It’s difficult to specify the exact mechanism,” Professor Morgan said, “but we think the protective effect for schizophrenia is related to compensatory cortical reorganisation in response to congenital or early cortical blindness. As a result, some functions that are impaired in schizophrenia may actually be enhanced in people with congenital or early cortical blindness.”
The investigators deliberately focused on blindness present at birth or emerging in early childhood because the brain shows greater plasticity at that stage. The increased potential for adaptive neural rewiring early in life is a plausible basis for durable protective changes in brain organization.
Beyond the academic interest, the authors suggest practical implications: if researchers can identify the specific neural changes that confer protection, it may be possible in the future to mimic those effects artificially. Such insight could inform early interventions aimed at reducing the risk or severity of schizophrenia in vulnerable individuals.
The study’s design—a whole-population cohort—adds weight to the results. In the cohort of 467,945 children born in Western Australia between 1980 and 2001, 1,870 (about 0.4%) developed schizophrenia and 9,120 (about 1.9%) developed a psychotic illness. Importantly, none of the 66 children identified with cortical blindness developed schizophrenia or other psychotic illnesses tracked in the study. A small number of children with peripheral blindness developed psychotic illness, but the protective association was specific to congenital or early cortical blindness rather than peripheral visual impairment.
These observations align with earlier smaller case reports and case series that hinted at a similar pattern. The current study strengthens that evidence by using comprehensive population data and formal diagnostic outcomes, reducing the risk that previous observations were due to chance or selective reporting.
Source: Jess Reid – University of Western Australia
Publisher: NeuroscienceNews.com (organized by NeuroscienceNews)
Image Source: Image adapted from the University of Western Australia news release.
Original Research: The study is titled “Congenital blindness is protective for schizophrenia and other psychotic illness. A whole-population study” by Vera A. Morgan, Melanie Clark, Julie Crewe, Giulietta Valuri, David A. Mackey, Johanna C. Badcock, and Assen Jablensky, published in Schizophrenia Research (December 2018).
DOI: 10.1016/j.schres.2018.06.061
Congenital blindness is protective for schizophrenia and other psychotic illness. A whole-population study
Using a population cohort of 467,945 children born in Western Australia from 1980 to 2001, researchers examined the prevalence of schizophrenia and broader psychotic illness in individuals with congenital or early blindness. Overall, 1,870 children (0.4%) developed schizophrenia and 9,120 (1.9%) developed a psychotic illness. None of the 66 children with cortical blindness developed schizophrenia or a psychotic illness. Among 613 children with peripheral blindness, a small number developed psychotic illness other than schizophrenia, and fewer developed schizophrenia. These results support earlier smaller reports suggesting that congenital or early cortical blindness, but not peripheral blindness, is associated with protection against schizophrenia.
The findings highlight a potentially important neurodevelopmental link between early sensory experience, cortical reorganisation and vulnerability to psychiatric disorders. Further research is needed to identify the precise neural adaptations involved and to explore whether those mechanisms can inform future preventive or therapeutic strategies for schizophrenia.