How can gaze tests help assess possible schizophrenia? How and where do they take place? We take stock with Dr. Anne Giersch.
Could a simple test to detect eye movement abnormalities help diagnose a disease such as schizophrenia? These are the findings of researchers in a study called “Simple Viewing Tests Can Detect Eye Movement Abnormalities That Distinguish Schizophrenia Cases from Controls with Exceptional Accuracyparue” in 2012 on Biological Psychiatry (Journal of Psychiatric Neuroscience and Therapeutics). So, what is the status of this eye test today?
Gaze test: the different tests under study
“The gaze test records where the pupillary reflex is located of the person by often projecting a little infrared on the eye”, deciphers researcher and research director at Inserm Anne Giersch. In other words, during this test, we follow the eye movement, with a preliminary calibration phase, and we know where the patient was looking at what time. As Anne Giersch, also a specialist in visual perceptions (she works in particular on eye tracking and schizophrenia), explains, there are also tests that explore transmission at the retina. “These two tests are very different, because the retina is an extension of the brain”, she distinguishes. In short, we look at transmission at the retina, because it is more accessible to observe than transmission in the brain. Concerning eye movements, there are several types of tests, explains Anne Giersch. There are, for example, very simple tests, quite removed from daily life, where the specialist will look at what is called the Smooth pursuit eye movement (SPEM) in English (eye tracking), that is to say following a target in regular movements. And for good reason, the majority of schizophrenic patients present a eye tracking disorder. Among other tests, some involve more than process of controlled memory or attention. The process here is that there is a target that appears on one side and the automatic movement consists of going to look at the side of this target, but the instruction is to go and look at the other side (the inhibition tasks and exploration tasks). According to the specialist, this examination is closest to the eye test: the idea is to see, if you show a face to a patient with schizophrenia, if he will look at the eyes, nose and mouth like everyone else, or not. However, she specifies, “spontaneously, in general, schizophrenic patients, like some autistic patients, do not do this and it is this avoidance of gaze that we will identify clinically”. On the other hand, if a patient suffering from schizophrenia is given a spot, most often, he will still explore the face normally. Note that these spontaneous image exploration abnormalities, can also be identified with geometric figures or via Rorschach tasks. THE Rorschach test has the main objective of reveal how a person processes information, but the way we perceive these ink stains can also shed light on the patient’s personality. As for the results of shape animation tests geometric, they make it possible to give an indication of a possible mental pathology of the patient. How ? By noting an anomaly in spontaneous exploration of information. “In general, what we describe are longer eye fixations in schizophrenic patients than in ‘control’ patients, as well as a reduction in what we call exploration spam., explains our expert. In other words, the area explored will be smaller in schizophrenic patients than in controls.
Where to perform these tests?
“These tests are research work carried out all over the world and in particular within the FondaMental Foundation* In Europe”, specifies Dr. Giersch. Currently, they belong only in the field of research for mental health, there is no direct application in daily clinic. Moreover, according to her, the use of equipment such as an eye tracker is not necessary to observe that a patient is not looking you in the eyes. On the other hand, these studies show significant differences between patient groups versus control groups. However, she adds, “we will have 20 to 30% of patients who perform exactly like the controls. Likewise, certain controls will not behave like the average control”.
In general, these tests are carried out on voluntary patients, discharged from hospitalization, but able to give informed consent. They are carried out on the recommendation of the psychiatrist or doctor in charge of the medical monitoring of schizophrenic patients. To be able to volunteer, patients must meet the criteria to participate in the study.
Gaze tests: schizophrenia and other mental disorders under study
Gaze test and schizophrenia: not yet a diagnostic criterion
“These are physiopathological studies, that is to say they are used to understand the pathology and not directly help the patient voluntary”, warns Anne Giersch. At this stage, this method is therefore not used to identify schizophrenia, it is not part of the diagnostic criteria. The gaze test belongs only to the field of medical research for now. “We do not use these tests to make the diagnosis, nor even to prevent the risk of developing schizophrenia”, she says. The only way to diagnose this disorder today is done through a psychiatrist who will study the person’s behavior and make a diagnosis if he notices so-called positive symptoms such as hallucinations and delusions as reported by Vidal. Psychiatric monitoring is accompanied by treatment based on medications and in particular by takingantipsychotics to treat psychotic patients. And for good reason, schizophrenia is an illness based on a set of symptoms, none of which is pathognomonic: for example, hallucinations, psychosis or delusional ideas – the best known symptoms – can be found in other pathologies, even in the so-called healthy population. The same applies to “negative” symptoms, such as withdrawal, having difficulty in contact with others or disorganization of thought. Medication-based treatment is essential, because this mental illness can seriously affect a person’s social and professional life. To find out more about the signs of possible schizophrenia, you can consult the video by Professor Pierre-Michel Llorca, head of the psychiatry department at Clermont-Ferrand University Hospital, on the FondaMental Foundation website.
*Specialist in mental illnesses, the FondaMental Foundation is one of the tools in Europe making it possible to act as a relay between research and laboratories, in order to propose new psychiatric techniques in clinical practice.