Memory loss (amnesia) is unusual forgetfulness.

The cause determines whether amnesia comes on slowly or suddenly, and whether it is temporary or permanent.

Normal aging may lead to trouble learning new material or requiring a longer time to remember learned material. However, it does not lead to dramatic memory loss unless diseases are involved.

• Aging
• Alcoholism
• Alzheimer's disease
• Brain damage due to disease or injury
• Brain growths (caused by tumors or infection)
• Brain infections such as Lyme disease or syphilis
• Depression or emotional trauma
• Drugs such as barbiturates or benzodiazepines
• Electroconvulsive therapy (especially if it is long-term)
• Encephalitis of any type (herpes, West Nile, Eastern Equine)
• General anesthetics such as halothane, isoflurane, and fentanyl
• Head trauma or injury
• Hysteria, often accompanied by confusion
• Illness that results in the loss of nerve cells (neurodegenerative illness)
• Nutritional problems (vitamin deficiencies such as low vitamin B12)
• Seizures
• Stroke or transient ischemic attack (TIA)
• Transient global amnesia
• Temporal lobe brain surgery