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

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.

Inclusion criteria

For all participants:

• Male or female, aged 18 to 60 years
• Subject having given their written consent to the study For Schizophrenia participants :

• Diagnosis of schizophrenia according to DSM-V criteria and stabilised for at least three months

For bipolar disorder participants :

• Diagnosis of bipolar disorders according to DSM-V criteria and stabilised for at least three months

For depressive disorders participants :

• Diagnosis of depressive disorders according to DSM-V criteria and stabilised for at least three months

Exclusion criteria

For all the participants :

• Subjects unable to give consent or not volunteering for the study.
• Current(s) somatic(s) condition(s)
• Specific ophthalmological problems (strabismus, amblyopia) incompatible with the devices stereoscopic (VR headsets)
• Head trauma's history with loss of consciousness
• Epilepsy history
• Intellectual disability
• Difficulties in understanding the French language
• Current or during the last 6 months of substance abuse or dependence (except tobacco)
• Freedom restriction by judicial or administrative decision and/or coercive hospitalisation
• Cybersickness history
• Pregnancy

For healthy control group :

• Current or previous psychiatric disorder
• Current psychotropic drug therapy