Causes

Normal memory function involves many parts of the brain. Any disease or injury that affects the brain can interfere with memory.

Amnesia can result from damage to brain structures that form the limbic system, which controls your emotions and memories. These structures include the thalamus, which lies deep within the center of your brain, and the hippocampal formations, which are situated within the temporal lobes of your brain.

Amnesia caused by brain injury or damage is known as neurological amnesia. Possible causes of neurological amnesia include:

• Stroke
• Brain inflammation (encephalitis) as a result of an infection with a virus such as herpes simplex virus, as an autoimmune reaction to cancer somewhere else in the body (paraneoplastic limbic encephalitis), or as an autoimmune reaction in the absence of cancer
• Lack of adequate oxygen in the brain, for example, from a heart attack, respiratory distress or carbon monoxide poisoning
• Long-term alcohol abuse leading to thiamin (vitamin B-1) deficiency (Wernicke-Korsakoff syndrome)
• Tumors in areas of the brain that control memory
• Degenerative brain diseases, such as Alzheimer's disease and other forms of dementia
• Seizures
• Certain medications, such as benzodiazepines or other medications that act as sedatives

Head injuries that cause a concussion, whether from a car accident or sports, can lead to confusion and problems remembering new information. This is especially common in the early stages of recovery. Mild head injuries typically do not cause lasting amnesia, but more-severe head injuries may cause permanent amnesia.

Another rare type of amnesia, called dissociative (psychogenic) amnesia, stems from emotional shock or trauma, such as being the victim of a violent crime. In this disorder, a person may lose personal memories and autobiographical information, but usually only briefly.