Schizophrenia is a debilitating mental illness characterized by psychosis (i.e., hallucinations, delusions) and cognitive deficits. Despite more than a century of research, the causes of schizophrenia are unclear. Recently, however, researchers discovered something that they think will help them understand why some people develop schizophrenia. Researchers discovered that people with schizophrenia have abnormal retinal blood vessels, which are blood vessels found at the back of the eye.
Dr. Madeline Meier and a team of researchers from Duke University used retinal imaging to study blood vessel abnormalities in 1,000 people from Dunedin, New Zealand. About 3% of those people had been diagnosed with schizophrenia. The research team found that study members diagnosed with schizophrenia were distinguished from healthy individuals and individuals with other medical and mental illnesses by wider veins in the back of the eye. This could mean that not enough oxygen and nutrient-rich blood is getting to the eye, and by extension, to the brain in people with schizophrenia. “We weren’t interested in blood vessels in the eye per se,” said Meier, the study’s lead author. “We were interested in blood vessels in the brain, but brain blood vessels are really hard to visualize. So the retinal blood vessels were the next best option.” Because eyes are see-through, they offer a non-invasive “window” into the condition of the brain blood vessels. The researchers were able to snap pictures of participants’ eyes with a retinal camera, and they used those pictures to detect blood vessel abnormalities.
This discovery was the focus of a major journal editorial recommending that researchers should approach schizophrenia as a systemic disease, as retinal blood vessels are reflective of the condition of the vasculature in the brain and body. Meier says the results of the study are important because (i) they suggest that problems with blood vessels may contribute to risk for developing schizophrenia, and (ii) they highlight the value of retinal imaging as a tool for schizophrenia research.
Meier has continued to do research in this area, and recently completed a study of retinal vessel abnormalities in young-adult twins from Australia. That study found that twins with psychosis symptoms, and their co-twins with no psychosis symptoms, had wider retinal veins than healthy individuals. “This is similar to what we found in the earlier study, but the new study adds new information by suggesting that wider retinal veins reflect familial risk for psychosis and schizophrenia,” Meier said. In other words, the new study indicates that wider veins are more likely to be a cause, rather than an effect, of illness.
Madeline Meier, Ph.D.
Department of Psychology
Arizona State University