Prefrontal Oscillations in Social Anxiety Disorder (POSAD) (POSAD)

Experimental fear in rodents is correlated with slow oscillations in electrical recordings of prefrontal cortex activities. The present study aims to test whether slow prefrontal oscillations is a biomarker of pathological anxiety in human subjects.

Fear and anxiety are adaptive responses that may become excessive or inappropriate in pathological conditions, as defined as anxiety disorders in DSM-5. These disorders, including phobic disorders such as social anxiety disorder, are frequent and impairing in the general population, with an estimated lifetime prevalence of 28% and significant consequences on quality of life. Direct and indirect medical costs related to these conditions amount to 74.4 billion €/year in Europe. Despite their prevalence, debilitating nature and chronicity, the pathophysiology of anxiety disorders is poorly understood and neurobiological treatments, including pharmacotherapy, are lacking efficacy. A better understanding of the neuronal mechanisms implicated in anxiety is necessary for the conception of new approaches to treat pathological anxiety. Anxiety is commonly modeled in animals using fear conditioning, which consists in associating a neutral stimulus (eg: a sound) with a mild electrical foot-shock. As a result of the association between sound and shock, sound presentation in isolation induces a set of conditioned behavioral responses, such as an immobilization ("freezing"). Previous studies have shown that the expression of fear responses, measured on the basis of freezing, is associated with the emergence of slow oscillations (2-6Hz) in medial prefrontal cortex (mPFC) of mice. Moreover, emergence of these oscillations in mPFC is predictive of the occurrence of freezing, and the artificial induction of 4 Hz oscillations in mPFC with optogenetics induces freezing. Finally, inhibiting neurons in mPFC during the ascending phase of this slow mPFC oscillation at the time of conditioned sound presentation is sufficient to significantly reduce fear. Interestingly, these results obtained in mice seem to find their prolongation in humans. Recent studies using fear conditioning in human subjects have also reported the emergence of prefrontal slow oscillations between 2-6 Hz during expression of conditioned fear responses. These results suggests that common mechanisms underlie the expression of fear in humans and rodents. However, whether similar neuronal circuits and mechanisms are implicated in human anxiety disorders remains unknown. This study aims at assessing the presence of slow mPFC oscillations during expression of anxiety in patients suffering from anxiety disorders. Beyond understanding of the neuronal mechanisms underlying anxiety expression, this study could provide a biomarker of anxiety with diagnostic and therapeutic implications.

First phase (go-no-go) with 10 subjects in 1 arm Second phase with 20 subjets (2 arms) in a cross-over design.

The presence of significant prefrontal oscillations in the EEG recording 2-6Hz band during in vivo social exposure (oral presentation to examiners) will be assessed in 10 subjects with social anxiety disorder. EEG will be recorded immediately before, during and after oral presentations to examiners. Psychometric evaluation will be performed prior to experimental sessions. Rating of anxiety levels will be performed by subjects using a Visual Analogue Scale of anxiety during each of the 3 experimental periods (wainting, presentation, recovery). Results of EEG recordings in the first 10 subjects will lead to continuation (presence of significant slow prefrontal oscillations during anxiety) or interruption (absence of signification oscillation) of the study.

In group 2.1, 10 subjects will undergo 2 sessions in a cross-over design with EEG recording immediately before, during and after: "real exposure": oral presentation to a panel of examiners "virtual reality" : oral presentation to virtual examiners Rating of anxiety levels will be performed by subjects using a Visual Analogue Scale of anxiety during each of the 3 experimental periods for each session. Psychometric evaluation will be performed prior to experimental sessions.

In group 2.2, 10 subjects will undergo 2 sessions in a cross-over design with EEG recording immediately before, during and after: "virtual reality" : oral presentation to virtual examiners "real exposure": oral presentation to a panel of examiners Rating of anxiety levels will be performed by subjects using a Visual Analogue Scale of anxiety during each of the 3 experimental periods for each session. Psychometric evaluation will be performed prior to experimental sessions.

Subjects will be invited to give a 5 minutes oral presentation on the topic of their choice to five examiners displaying no facial emotional reaction, after a 5 minutes period of silent waiting in front of the examiners. This waiting period is prompt to elicit anticipation-type of social anxiety.

Subjects will give a 5 minutes oral presentation on the subject of their choice to a virtual reality panel composed of 5 examiners displaying no facial emotional reaction, after a 5 minutes period of silent waiting in front of the examiners. This waiting period is expected to elicit anticipation-type of social anxiety.

EEG will be recorded with a standard 16-electrodes cap. Recordings will start before the 5 minutes waiting period and continue throughout oral presentation and recovery. The recovery period will be used as a baseline control

Subjects will be evaluated prior to inclusion using the following assessment tools Anamnestic Association for Methodology and Documentation in Psychiatry (AMDP) questionnaire Mini International Neuropsychiatric Interview (MINI 6.0, for psychiatric diagnoses) Liebowitz Social Anxiety Scale (LSAS) Montgomery Asberg Depression Rating Scale (MADRS) Brief Anxiety Scale of Tyrer (BAS) State-Trait Anxiety Inventory (STAI A-B) Global Assessment of Functioning (GAF)

Subjects will be asked to rate their anxiety levels immediately before (5 minutes of silent waiting), during and after the 5-minute oral presentation (recovery)

Change in power of slow oscillations in prefrontal EEG recordings during anticipation relative to baseline

The change in power of PFC 2-6 Hz oscillations between the 5-minutes waiting period before oral presentation and the recovery period will be computed as a ratio. Detection of exaggerated 2-6Hz oscillations in prefrontal cortex during anxious anticipation is the primary aim of this study.

Time-frequency analysis will be performed to determine the duration of 2-6Hz prefrontal oscillations epochs and total duration of these oscillations within experimental period. Significant oscillatory epochs will be defined using power ratios. These metrics will be used in order to assess the neurobiological and clinical relevance of this biomarker.

Change in power of slow oscillations in prefrontal EEG recordings during presentation relative to baseline

The change in power of PFC 2-6 Hz oscillations between the 5-minutes oral presentation and the recovery period will be computed as a ratio.

Time-frequency analysis will be performed to determine the duration of 2-6Hz prefrontal oscillations epochs and total duration of these oscillations within experimental period. Significant oscillatory epochs will be defined using power ratios.

Correlation will be calculated between PFC 2-6 Hz oscillations power and the visual Analogue anxiety score during the 5 minutes period before presentation.

Correlation will be calculated between PFC 2-6 Hz oscillations power and the visual Analogue anxiety score during presentation.

Correlation will be calculated between PFC 2-6 Hz oscillations duration and the visual Analogue anxiety score during the 5 minutes period before presentation.

Correlation will be calculated between PFC 2-6 Hz oscillations duration and the visual Analogue anxiety score during presentation.

Correlation will be calculated between PFC 2-6 Hz oscillations power during the 5 minutes before presentation and STAI-B scores

During the 5 minutes before oral presentations (PFC oscillations power) and prior to inclusion (STAI-B rating)

Correlation will be calculated between PFC 2-6 Hz oscillations power during presentation and STAI-B scores

During the 5 minutes oral presentation (PFC oscillations power) and prior to inclusion (STAI-B rating)

Correlation will be calculated between PFC 2-6 Hz oscillations duration during the 5 minutes before presentation and STAI-B scores

During the 5 minutes before oral presentation (PFC oscillations duration) and prior to inclusion (STAI-B rating)

Correlation will be calculated between PFC 2-6 Hz oscillations duration during presentation and STAI-B scores

During the 5 minutes oral presentation (PFC oscillations duration) and prior to inclusion (STAI-B rating)

Correlation will be calculated between PFC 2-6 Hz oscillations power during the 5 minutes before presentation and STAI-A scores

During the 5 minutes before oral presentation (PFC oscillations power) and prior to inclusion (STAI-A rating)

Correlation will be calculated between PFC 2-6 Hz oscillations power during presentation and STAI-A scores

During the 5 minutes oral presentation (PFC oscillations power) and prior to inclusion (STAI-A rating)

Correlation will be calculated between PFC 2-6 Hz oscillations duration during the 5 minutes before presentation and STAI-A scores

During the 5 minutes before oral presentation (PFC oscillations duration) and prior to inclusion (STAI-A rating)

Correlation will be calculated between PFC 2-6 Hz oscillations duration during presentation and STAI-A scores

During the 5 minutes oral presentation (PFC oscillations duration) and prior to inclusion (STAI-A rating)

Correlation between prefrontal slow oscillations power during anticipation and levels of social anxiety

Correlation will be calculated between PFC 2-6 Hz oscillations power during the 5 minutes before presentation and LSAS scores

During the 5 minutes before oral presentation (PFC oscillations power) and prior to inclusion (LSAS rating)

Correlation between prefrontal slow oscillations power during presentation and levels of social anxiety

Correlation will be calculated between PFC 2-6 Hz oscillations power during presentation and LSAS scores

Correlation between prefrontal slow oscillations duration during anticipation and levels of social anxiety

Correlation will be calculated between PFC 2-6 Hz oscillations duration during the 5 minutes before presentation and LSAS scores

During the 5 minutes before oral presentation (PFC oscillations duration) and prior to inclusion (LSAS rating)

Correlation between prefrontal slow oscillations duration during presentation and levels of social anxiety

Correlation will be calculated between PFC 2-6 Hz oscillations duration during presentation and LSAS scores

During the 5 minutes oral presentation (PFC oscillations duration) and prior to inclusion (LSAS rating)

Correlation between prefrontal slow oscillations power during anticipation and levels of general anxiety

Correlation will be calculated between PFC 2-6 Hz oscillations power during the 5 minutes before presentation and BAS scores

During the 5 minutes before oral presentation (PFC oscillations power) and prior to inclusion (BAS rating)

Correlation between prefrontal slow oscillations power during presentation and levels of general anxiety

Correlation will be calculated between PFC 2-6 Hz oscillations power during presentation and BAS scores

Correlation between prefrontal slow oscillations duration during anticipation and levels of general anxiety

Correlation will be calculated between PFC 2-6 Hz oscillations duration during the 5 minutes before presentation and BAS scores

During the 5 minutes before oral presentation (PFC oscillations duration) and prior to inclusion (BAS rating)

Correlation between prefrontal slow oscillations duration during presentation and levels of general anxiety

Correlation will be calculated between PFC 2-6 Hz oscillations duration during presentation and BAS scores

During the 5 minutes oral presentation (PFC oscillations duration) and prior to inclusion (BAS rating)

Correlation will be calculated between PFC 2-6 Hz oscillations power during the 5 minutes before presentation and MADRS scores

During the 5 minutes before oral presentation (PFC oscillations power) and prior to inclusion (MARDS rating)

Correlation will be calculated between PFC 2-6 Hz oscillations power during presentations and MADRS scores

During the 5 minutes oral presentation (PFC oscillations power) and prior to inclusion (MARDS rating)

Correlation will be calculated between PFC 2-6 Hz oscillations duration during the 5 minutes before presentation and MADRS scores

During the 5 minutes before oral presentation (PFC oscillations duration) and prior to inclusion (MARDS rating)

Correlation will be calculated between PFC 2-6 Hz oscillations duration during presentation and MADRS scores

During the 5 minutes oral presentations (PFC oscillations duration) and prior to inclusion (MARDS rating)

Inclusion Criteria: Social anxiety disorder as defined in DSM-5 Full understanding of the protocol Obtaining informed consent from study subjects before or at inclusion at the latest Being registered in the french national health insurance service (Sécurité Sociale) (or equivalent) Exclusion Criteria: Active medical co-morbidity including severe hypertension, cardiac insufficiency, Raynaud syndrome, diabetes mellitus, renal insufficiency, adrenal insufficiency, Cushing syndrome and epilepsy Severe neurological co-morbidity, including but not limited to Parkinson's disease and multiple sclerosis Long-term corticotherapy History of significant head injury, defined by loss of consciousness Being diagnosed with another major psychiatric condition (DSM5) including bipolar disorder and schizophrenia or substance/alcohol use disorder; with the exception of major depressive disorder and nicotine use disorder Suicidal risk evaluated as moderate to high in the MINI questionnaire initiation of a psychotropic treatment or change in the dose of ongoing psychotropic treatment within 3 days prior to each visit and including: antidepressant treatments with selective serotonin recapture inhibitors, serotonin and norepinephrine inhibitors, alpha2-presynaptic adrenoreceptors (mirtazapine, mianserin), tricyclic anxiolytic drugs including benzodiazepines and anti-histamine antipsychotic drugs Acute alcohol intake 2 days prior to each visit (inclusion, experimental sessions) Pregnancy or breastfeeding. Ongoing hospitalization without consent (decision of a third-party: medical, justice)

Centre Hospitalier Charles Perrens, Bordeaux; INRA NutriNeuro, Bordeaux; Université de Bordeaux, France

Centre Hospitalier Charles Perrens, Bordeaux; INRA NutriNeuro, Bordeaux; Université de Bordeaux, France