Symptom of Amnesia is memory loss. This can be caused by a head injury or suppression of some tramatic event. It can also come with age that there is severe memory loss or even because of illness. There can either be short-term memory loss or long-term memory loss. The length of amnesia can be short or long. ("Amnesia")
This picture right here shows common causes and symptoms associated with amnesia. This shows that Confusion is part of all the causes and head trauma can bring about almost all of the symptoms.