Phenomenological Explorations of the Esketamine-Induced Transient Dissociative State

Ketamine is an anaesthetic used in low doses to treat depressive disorders. A related molecule, Esketamine, has recently been launched on the market for the treatment of resistant depression. One of the side effects of ketamine, like Esketamine, is induction of transient dissociative state. Dissociation has been described as disruption in continuity of conscious thought and emotion, cognitive processes disorganisation and an alteration in self-perception and environment perception. A study of healthy volunteers receiving ketamine showed that this state was manifested by altered sensory perceptions, with increased noise sensitivity, visual distortions and altered time perception. Few studies have looked at this phenomenon in the Esketamine context. However, it is a frequent side effect. With ketamine, it has been shown that anxiety associated with dissociative experience reduces the antidepressant effect. Benzodiazepines use for anxiolytic purposes is also thought to limit the antidepressant effect. It is necessary to explore the Esketamine induced transient dissociative state in order to clarify this state and develop therapeutic strategies. The investigators have chosen a phenomenological approach, which is the only way to evaluate consciousness contents and structures, in order to explore this state using the experiential phenomenological interview.