Study of Bipolar Disorders and Retinal Electrophysiological Markers

The BIMAR study aims to compare electrophysiological data measured with electroretinogram (ERG) and electroencephalogram (EEG) between a group of euthymic patients with bipolar disorder (BD) and a group of healthy controls subjects.

Secondarily, the investigators also want to:

* Compare combined electrophysiological measurements with ERG and EEG between the two groups.
* Identify relations between clinical, neuropsychological and circadian phenotypes in patients with BD and electrophysiological measurements measured with ERG and EEG.

The main hypothesis of the investigators is that differences exist in the ERG and EEG measurements between subjects with BD and healthy subjects. Those differences could be identified as candidate markers for BD which, if confirmed in later studies, could be used in current practice to guide the management of patients with BD.

Bipolar disorders (BD) is a common, chronic and disabling psychiatric condition. In addition to being characterized by significant clinical heterogeneity, notable disturbances of sleep and cognitive function are frequently observed in all phases of the disease. Currently, there is no readily available biomarker in current clinical practice to help diagnose or predict the disease course. Thus, identification of biomarkers in BD is today a major challenge. In this context, the study of electrophysiological biomarkers based on electroretinogram (ERG) and electroencephalogram (EEG) measurements in BD seems highly promising. The BiMAR study aims to compare electrophysiological data measured with ERG and EEG between a group of euthymic patients with BD and a group of healthy control subjects. Secondarily, the investigators will also describe the existing potential relationship between clinical, sleep and neuropsychological phenotypes of patients and electrophysiological data.

The BiMAR study is a comparative and monocentric study carried out at the Expert Center for BD in Nancy, France. In total, 70 euthymic adult patients with BD and 70 healthy control subjects will be recruited. Electrophysiological recordings with ERG and EEG will be performed with a virtual reality headset after a standardized clinical evaluation to all participants. Then, an actigraphic monitoring of 21 consecutive days will be carried out. At the end of this period a neuropsychological evaluation will be performed during a second visit. The primary outcome will be electrophysiological measurements with ERG flash and pattern. Secondary outcomes will be EEG data, sleep settings, clinical and neuropsychological assessments. For patients only, a complementary ancillary study, carried out at the University Hospital of Nancy, will be proposed to assess the retinal structure and microvascularization using Optical Coherence Tomography. Recruitment will begin in December 2021 and will continue until the end of June 2023.

The BiMAR study will contribute to identifying candidate ERG electrophysiological markers for helping the diagnosis of BD and identify subgroups of patients with different clinical profiles. Eventually, this would allow earlier diagnosis and personalized therapeutic interventions.

Eligibility Criteria:
Inclusion criteria :

1. Patients:

   * been diagnosed with BD according to the Diagnostic and Statistical Manual of Mental Disorders - 4th edition (DSM-IV) diagnostic criteria using the Mini International Neuropsychiatric Interview (MINI)
   * currently euthymic for at least 3 months prior to the study, as defined by a score below 10 on the Montgomery-Asberg Depression Rating Scale (MADRS) which assesses depression and by a score below 8 on the Young Mania Rating Scale (YMRS) which assesses mania
   * age 18 or more
2. Healthy volunteers:

   * not suffer from a personal psychiatric pathology verified with the MINI
   * age 18 or more

Exclusion criteria for all participants (patients and healthy volunteers):

* suffer from psychiatric pathology or substance use disorders according to DSM-IV criteria measured with the MINI, excluding BD for the patient group
* suffer from neurological or retinal pathology
* having a shift work or a get-lag in the last 15 days
* criteria incompatible with the use of the virtual reality headset (Retinaute®,BioSerenity) like having an allergy to one of the components of the textile
* persons treated by sismotherapy during the past year
* persons with an uncorrected visual impairment or disabling hearing impairment that does not allow neuropsychological tests to be performed
* subjects with an intellectual disability making it difficult to participate in the study or to understand and follow informations provided to them
* adults legally protected
* pregnant or breastfeeding women
* subjects already participating in another interventional trial