Contribution of Virtual Reality Eye Tracking in the Identification of Schizophrenia, Bipolar and Depression

Overview

Schizophrenia (SCZ), bipolar disorder (BP), and depression (DEP) are systematically associated with a severe impairment of the overall abilities of patients, which precludes them from functioning adequately in daily life. A large body of literature emphasises the importance of identifying specific markers for these pathologies to prevent or anticipate the emergence of new psychopathological symptoms. As a result, one of the current research challenges is to develop new, faster, and more reliable tools. Eye movements are physiological signs involving brain areas that control cognitive processes. These same processes could be altered in psychiatric disorders, and these alterations could produce many eye movement abnormalities. The literature highlights some eye movement abnormalities specific to each targeted pathology. However, to our knowledge, no study has compared eye movement abnormalities in a virtual environment projected in a head-mounted display (HMD). The investigators hypothesised that an eye tracker connected to an HMD could identify specific eye movement abnormalities of SCZ, BP, and DEP. Recording eye movements specific to these pathologies in pseudo-ecological situations could lead to better identification methods.

Schizophrenia (SCZ), bipolar disorder (BP), and depression (DEP) are among the most incapacitating pathologies. Specific abnormalities such as characteristics of fixations (stability of the eye) and saccades (movement between one fixation point to an another) are proposed as endophenotypic markers of these diseases, particularly in SCZ and BP. In SCZ, literature reports as core abnormalities a saccadic pursuit in the Smooth Pursuit Eye Movement (SPEM) and a restricted field of exploration in free-viewing. In BP, fixation times and eye movement velocity during free-viewing differ from those identified in SCZ. When psychotic features are present, BP's pursuit movement is similar to SCZ's. Moreover, eye movement abnormalities are correlated with the presence of manic/hypomanic or depressive symptoms, even in or saccadic paradigms (i.e., anti-saccade or guided memorisation). In DEP, eye movements are significantly different from BP regarding movement velocity, while fixation times are similar in the saccade or free viewing paradigms. In addition, pursuit movements are not saccadic in the SPEM task. Nevertheless, studies do not necessarily use equipment with the same performance, and eye-tracking technology constantly evolves. Eye-tracking can now be included in Virtual Reality (VR) Head- Mounted Displays, permitting the creation of new pseudo-ecological paradigms. The investigators hypothesise that abnormalities in eye movements in SCZ, BP, and DEP will be identifiable in VR environments compared to healthy controls, and could differentiate them one from the other. Participants will be assessed using scales and questionnaires and eye-tracking in VR environments. The data will be analysed using statistical processing to identify significant differences in eye movements between SCZ, BP, and DEP and healthy controls.