Schizophrenia – a serious mental illness often associated with psychosis – has long been a mystery. Over the past century, researchers have viewed it as a disease of the mind and sometimes even associated it with poor parenting. Although the symptoms have now been determined to be biological in origin and some of the risk factors have been identified, their exact causes remain unclear. Because of this, the diagnosis is complicated and can be subjective.
To improve diagnosis and treatment, researchers have sought biomarkers – measurable physiological signals that can indicate the onset and progression of disease. Over the past decade, research has begun to point to a promising source of such signals: the eye. For example, the thickness of the retina or the reaction to light stimuli can be the first signs that a person is affected or is at risk of developing the disease. "The retina is essentially an indicator of what's happening in the brain," says Steven Silverstein, a clinical psychiatrist at Rutgers University in Piscataway, New Jersey.
The connection between eye and brain health
Eye exams could allow doctors to detect neurological and neuropsychiatric deficits early. The potential for using the eye as a “window to the brain” goes beyond schizophrenia. Changes in the condition or function of the eye may indicate the presence and development of neurological diseases as well as brain injuries such as concussions. Based on these hypotheses, researchers are now using improved imaging technology to develop simple, minimally invasive eye and vision tools to screen, diagnose and monitor neurological and mental illnesses.
Electroretinography for diagnostics
The most promising diagnostic tool is now electroretinography (ERG), a simple and minimally invasive test that measures the electrical response of the retina to light stimuli.
A team of researchers led by clinical psychiatrist Michel Maziade from the University of Laval in the Canadian city of Quebec used electroretinography to determine how the response of light-sensitive cells in the retina changes in people at risk of neuropsychiatric disorders such as schizophrenia and major depressive disorders. In 2010, researchers found that the cells of young people with a high genetic risk of developing physical cancer respond weaker to light than those who are not at this risk.
The results are impressive, but further research is needed to determine the relationships between the retina and symptoms before ERG can be used for diagnosis in clinics and practices.
