The most common symptom of dissociative amnesia is memory loss.
Memory loss may involve any of the following:
- Localised Amnesia:
- A specific event or events or a specific period of time, such as the months or years of being abused as a child or the days spent in intense combat.
- Selective Amnesia:
- Only certain aspects of an event or only certain events during a period of time.
- Generalised Amnesia:
- Personal identity and entire life story, sometimes including well-learned skills and information about the world.
- Systematised Amnesia:
- Information in a specific category, such as all information about a particular person or about their family.
- Continuous Amnesia:
- Each new event as it occurs.
Generalised amnesia is rare and usually begins suddenly. It is more common among:
- Combat veterans;
- Individuals who have been sexually assaulted; and
- Individuals experiencing extreme stress or conflict.
Amnesia may not appear immediately after a traumatic or stressful event. It may take hours, days, or longer to appear.
Shortly after loss of memory, some individuals seem confused, some are very distressed, whilst others are strangely indifferent.
Most individuals with dissociative amnesia have one or more gaps in their memory. Gaps usually span a few minutes to a few hours or days but may span years, decades, or even an entire life.
Most individuals are unaware or only partly aware that they have gaps in their memory. They become aware only later, when memories reappear or they are confronted with evidence of things that they have done but do not recall.
Affected individuals have difficulty forming and maintaining relationships.
Some individuals have flashbacks, as occur in post-traumatic stress disorder (PTSD). That is, they relive events as if they were actually happening, and they are unaware of their subsequent personal history – for example, that they survived the trauma.
Flashbacks may alternate with amnesia for what happened during the flashback. Some individuals with dissociative amnesia develop PTSD later, especially when they become aware of the traumatic or stressful events that triggered their amnesia.
Individuals may also have vague symptoms, such as fatigue, weakness, or problems sleeping. Depression and suicidal and other self-destructive behaviours (such as substance abuse and reckless sexual behaviour) are common.
Risk of suicidal behaviours may be increased when amnesia resolves suddenly and people are overwhelmed by traumatic memories.
Rarely, individuals with an extreme form of dissociative amnesia suddenly travel from their home for a period of time. During this time, they do not remember some or all of their past life, including who they are (their identity). These episodes are called dissociative fugues.
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