Post-traumatic stress disorder (PTSD) is a set of symptoms that can be developed as a result of exposure to a traumatic event or events that can range in prevalence from 25% to 75%. While therapeutic management combines psychotherapy, drug therapy and social support, some PTSD remain resistant after early and appropriate initial treatment. In terms of physiopathology, several studies have shown that parasympathetic activity is significantly decreased in patients with PTSD. In scuba diving, the cardio-vascular stresses associated with submersion of the subject and the lungs due to breathing in a regulator are at the origin of a reflex activation of the parasympathetic nervous system. The objective is to study the effects of the scuba diving activities-induced autonomic parasympathetic nervous system activation on the symptomatic progression of patients with PTSD.

The study population will consist of patients monitored and treated for PTSD following the attacks of 14/07/2016 in Nice (France).

A group will be composed of patients (n=12) who will complete a Scuba Diving Discovery Course (GP+ Diving Group). This course, lasting 2 weeks, will consist of a daily dive, 5 days per week, for a total of 10 dives. These will be supervised by a graduate instructor according to the rules of supervision defined by the sport code. The dives will be conducted in open air, at a maximum depth of 6 meters for a maximum duration of 20 minutes.

A matched group (gender, age, height, weight and BMI) will be composed of patients (n=12) who will not complete the Scuba Diving Discovery Course (GP- Virtual reality group). The subjects of this group will follow virtual reality sessions recreating the environment in which the scuba divers of the GP+ group operate. A control group (GT) will be composed of patients (n=12) who are monitored and treated for PTSD and who will not attend the dive discovery course or virtual reality sessions.

• The main evaluation criterion will be the NON-INVASIVE determination of salivary alpha amylase.
• Secondary evaluation criteria will be heart rate variation, CGI, HAD and BECK Anxiety, EGF, PCL-S and IES questionary.

The main objective is to study the effects of immersion and pressure relief ventilation on the activation of the autonomic parasympathetic nervous system.

Secondary objectives are to assess the symptomatic impact of parasympathetic autonomic nervous system activation on overall improvement, anxiety and depressive symptoms, functioning, and the 3 subtypes of PTSD symptoms as vegetative neuro hyperactivity, invasive syndrome and avoiding

Inclusion Criteria:

• Adult patients
• Patients who understand and read French
• Patients who have signed the informed consent form
• Patients who have never practiced scuba diving
• Patients medically fit for scuba diving
• Patients with the DSM-5 criteria for Post-traumatic Stress Disorder
• PCL-S score strictly greater than 44
• CGI greater than or equal to 4
• Chronicity (duration greater than 3 months)

Exclusion Criteria:

• Women of reproductive age without contraception
• Pregnant or nursing women
• Patients under guardianship or curatorship and detainees of justice
• Patients who previously practised scuba diving or hold a diving certificate
• Patients whose medical condition medically contraindicated the practice of scuba diving,
• Patients having a water phobia, bipolar or psychotic disorder
• Patients with a severe and proven suicidal risk (MINI-S and medical examination)
• Patients treated for less than 2 months with antidepressants;
• Patients treated for less than 2 months with specific psychotherapy (Cognitive and Behavioural Therapy, EMDR)
• Patients with response to treatment (50% decrease in symptoms)
• Contraindications to the practice of virtual reality.