An amnesic subject who earnestly tells stories about his past that are demonstrably untrue is showing the symptom known as Fugue state
this disorder characterized by the presence of two or more distinct personality states and this disorder is also known as Dissociative identity disorder.
The onset of a dissociative fugue state is usually sudden and follows a traumatic or highly stressful event such as natural disasters and wars, as well as severe marital or financial distress, alcohol abuse, depression, and a history of child abuse
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