What mental state is Stan likely experiencing when he denies being David and his former life?

The mental state that Stan is likely experiencing is dissociative fugue. Dissociative fugue is a disorder characterized by a temporary loss of personal identity and the inability to recall important autobiographical information, often triggered by trauma or stress. In cases of dissociative fugue, individuals may travel away from their home or customary work locations and assume a new identity, which aligns with Stan's denial of being David and his former life. This suggests a disconnection from his memories and identity, which is central to this particular dissociative disorder.

In contrast, post-traumatic stress disorder (PTSD) involves symptoms like flashbacks, avoidance, and hyperarousal after experiencing a traumatic event, but does not typically cause an individual to deny their identity outright. Mania, which is often associated with bipolar disorder, is characterized by elevated mood, increased energy, and impulsivity, but does not usually affect personal identity in the way dissociative fugue does. Agoraphobia is an anxiety disorder characterized primarily by the fear of situations that might cause panic attacks or feelings of being trapped, and it does not involve identity confusion. Thus, dissociative fugue best encapsulates Stan's experience of disavowing his previous self and life.