In the action-packed Bourne Trilogy, Matt Damon's character, Jason Bourne, loses all memory of his past self. Just how common is amnesia like this? Amnesia is a condition in which certain memories are lost or become inaccessible. One type of amnesia occurs when a person mentally blocks out certain information, usually as a result of emotional shock, stress, or trauma. This was once known as psychogenic amnesia, and is known today as dissociative amnesia. Traumatic events that can lead to dissociative amnesia include: military combat, natural disasters, terrorist acts, and physical or sexual abuse. Jason Bourne, of the Bourne Identity books and films, was tormented by merciless government training and work-related trauma, suffered from this type of amnesia. For Bourne, intense dissociative amnesia caused a complete loss of all sense of identity and history. This rare condition is called a fugue state, and it usually only lasts a few hours or days. More often, dissociative amnesia includes gaps in memory for large spans of time, or missing memories surrounding the precipitating traumatic event. It's important to understand that dissociative amnesia is different from organic amnesia, in which brain damage or injury is directly responsible for the loss of memory. In dissociative amnesia, memories are not really lost. Instead, they are buried deep within the mind. These memories may resurface on their own, or may be triggered by a person's surroundings. It makes sense that dissociative amnesia can cause a great deal of hardship, and may lead to depression or anxiety. For this reason, it's important to seek help from a doctor if symptoms of the condition are present. A physician will rule out physical illness or medication side effects before referring a patient to a mental health professional for treatment. The goal of treatment is to help a person safely access and express painful memories. Psychotherapy, which involves one-on-one communication with a therapist, is one option. Another is clinical hypnosis, in which doctor-induced relaxation causes a patient to reach a heightened state of awareness. While there are no medications specifically approved to treat amnesia, patients suffering from anxiety or depression may benefit from drugs that treat these conditions. For most people with dissociative amnesia, memory returns with time. Although it took three films and seven novels, even Jason Bourne regained his missing memories in the end!