A 16-Year-Old Girl Is Brought to the Emergency Department After

A 16-year-old girl is brought to the emergency department after being found in a confused state at a rest area along an interstate highway in Michigan. The patient was unable to answer questions from the police about her name, address, or any other information regarding her person. A telephone call with the police department of her hometown reveals that she had been reported missing three days ago by her husband. When her parents arrive, they report that their son was died due to an accidental drowning one week ago. The mother is concerned that her daughter seems to be unaware of her brother's death and believes she is "in denial."  Physical and neurological examinations show no abnormalities. On mental status examination, she is oriented only to time and place but not to person. Short-term memory is intact; she does not recognize her parents or recall important life events. Which of the following is the most likely diagnosis?

A) Adjustment disorder
B) Complicated grief reaction
C) Conversion disorder
D) Dissociative amnesia
E) Posttraumatic stress disorder