Dissociative Amnesia

Dissociative amnesia is inability to recall important autobiographical information, usually traumatic or stressful, too extensive for ordinary forgetting.

• Prevalence about 1.8% in a year; types: localised, selective, generalised, systematised; with dissociative fugue (purposeful travel with amnesia).
• Triggers: acute trauma, combat, abuse, severe stress, legal or financial crisis.
• Onset sudden; recovery often abrupt, may be spontaneous or after removal from stress.
• Comorbid depression, PTSD, personality disorders.

• Gaps in memory for events or personal identity, patient may be unaware or distressed; intact new learning and general knowledge.
• Perplexity, wandering or fugue, depersonalisation.
• Neurological examination normal.

• Exclude organic causes: head injury, epilepsy (EEG), encephalitis, stroke, transient global amnesia, substance intoxication (alcohol blackouts, benzodiazepines), dementia, Wernicke-Korsakoff.
• Investigations: MRI brain, EEG, toxicology, metabolic screen, as indicated.
• Psychiatric evaluation with collateral history and dissociation scales.
• Assess safety, suicide risk and ongoing trauma.

• Safe, supportive environment, reassurance, removal from stressors; memories often return spontaneously.
• Psychotherapy: supportive and trauma informed, gradual retrieval with cues; hypnosis or amobarbital interviews only in specialist settings, with risk of false memories.
• Treat comorbid depression and PTSD (sertraline 50 to 200 mg).
• Address legal and social consequences.
• Follow up for recurrent episodes and trauma processing.