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"Amnesiac" redirects here. For the Radiohead album, see Amnesiac (album). For other uses, see Amnesia (disambiguation).
Main article: Memory disorder
Classification and external resources
ICD-10 F04, R41.3
ICD-9 294.0, 780.9, 780.93
MedlinePlus 003257
MeSH D000647




French psychologist Theodule-Armand Ribot was among the first scientists to study amnesia. He proposed Ribot's Law which states that there is a time gradient in retrograde amnesia. The law follows a logical progression of memory-loss due to disease. First, a patient loses the recent memories, then personal memories, and finally intellectual memories. He implied that the most recent memories were lost first.[8]

Important case studies[edit]


Henry Molaison[edit]

Henry Molaison, formerly known as H.M., changed the way people thought of memory. He was a patient who suffered from severe epilepsy. Physicians were unable to control his seizures with drugs, so they tried a new approach involving brain surgery. Doctors removed his medial temporal lobe bilaterally by doing a temporal lobectomy. His epilepsy did improve, but Molaison lost the ability to form new long-term memories (anterograde amnesia). He exhibited normal short-term memory ability. If he was given a list of words, he would forget them in about a minute's time. In fact, he would forget that he was even given a list in the first place.[9] Once Molaison stopped thinking about the lists he was unable to recall them again from long term memory. This gave researchers evidence that short-term and long-term memory are in fact two different processes.[10] Even though he forgot about the lists, he was still able to learn things through his implicit memory. The psychologists would ask him to draw something on a piece of paper, but to look at the paper using a mirror. Though he could never remember ever doing that task, he would improve after doing it over and over again. This showed the psychologists that he was learning and remembering things unconsciously.[11] Studies were completed consistently throughout Molaison’s lifetime to discover more about amnesia.[1] Researchers did a 14-year follow-up study on Molaison. They studied him for a period of two weeks to learn more about his amnesia. After 14 years, Molaison still could not recall things that have happened since his surgery. However, he can still remember things that happened prior to the operation. Researchers also found that, when asked, Molaison could answer questions about national or international events, but he could not remember his own personal memories.[9] After his death Molaison donated his brain to science, where they were able to discover the areas of the brain that had the lesions which caused his amnesia.[10] This case study provided important insight to the areas of the brain that are affected in anterograde amnesia, as well as how amnesia works.

Patient R.B.[edit]

Patient R.B. was a normally functioning man up until the age of 52. At Age 50 he had been diagnosed with angina and had surgery for heart problems on two occasions. After an ischemic episode (reduction of blood to the brain) that was caused from a heart bypass surgery, R.B. demonstrated a loss of anterograde memory, but almost no loss of retrograde memory, with the exception of a couple of years before his surgery, and presented no sign of any other cognitive impairment. It wasn’t until after his death that researchers had the chance to examine his brain, when they found his lesions were restricted to the CA1 portion of the hippocampus. This case study led to important research involving the role of the hippocampus and the function of memory.[12]

Patient G.D.[edit]




  • Head trauma is a very broad range as it deals with any kind of injury or active action toward the brain which might cause amnesia. Retrograde and Anterograde amnesia are more often seen from events like this, an exact example of a cause of the two would be electroshock therapy, which would cause both briefly for the receiving patient.
  • Physical deficiencies are different from head trauma as physical lean more toward passive physical issues. The difference would be having surgery that removes part of your brain, this would be active and thus head trauma, while the surgery caused the surrounding areas to atrophy, which is passive. Henry Molaison is a great example of physical deficiencies as parts of his brain began to atrophy after his surgery.[1]

Amongst specific causes of amnesia are the following:


  • Anterograde amnesia refers to the inability to create new memories due to brain damage, while long-term memories from before the event remain intact. The brain damage can be caused by the effects of long-term alcoholism, severe malnutrition, stroke, head trauma, surgery, Wernicke-Korsakoff Syndrome, cerebrovascular events, anoxia or other trauma.[18] The two brain regions related with this condition are medial temporal lobe and medial diencephalon. Anterograde amnesia can't be treated with pharmacological methods due to neuronal loss.[19] However, treatment exists in educating patients to define their daily routines and after several steps they begin to benefit from their procedural memory. Likewise, social and emotional support is critical to improving quality of life for anterograde amnesia sufferers.[19]
  • Source amnesia is the inability to remember where, when or how previously learned information has been acquired, while retaining the factual knowledge.[27] Source amnesia is both part of ordinary forgetting and can be a memory disorder caused by different factors.[28] People suffering from source amnesia can also get confused about the content of what is remembered. This confusion has been loosely termed memory distrust syndrome. Individuals who suffer from this syndrome distrust their memory and may be motivated to rely on external (non-self) sources.[28]

Acquisition of new memories[edit]


Acquisition of new declarative information[edit]


Acquisition of new non-declarative information[edit]



Many forms of amnesia fix themselves without being treated.[31] However, there are a few ways to cope with memory loss if that is not the case. One of these ways is cognitive or occupational therapy. In therapy, amnesiacs will develop the memory skills they have and try to regain some they have lost by finding which techniques help retrieve memories or create new retrieval paths.[32] This may also include strategies for organizing information to remember it more easily and for improving understanding of lengthy conversation.[33]

While there are no medications available to treat amnesia, underlying medical conditions can be treated to improve memory. Such conditions include but are not limited to low thyroid function, liver or kidney disease, stroke, depression, bipolar disorder and blood clots in the brain.[34] Wernicke–Korsakoff syndrome involves a lack of thiamin and replacing this vitamin by consuming thiamin-rich foods such as whole-grain cereals, legumes (beans and lentils), nuts, lean pork, and yeast.[31] Treating alcoholism and preventing alcohol and illicit drug use can prevent further damage, but in most cases will not recover lost memory.[33]


See also[edit]


  2. ^ "Amnesia." The Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. 4th ed. Vol. 1. Detroit: Gale, 2008. 182-184. Gale Virtual Reference Library.
  3. ^ Schacter, Daniel. L "Psychology"
  4. ^ D. Frank Benson, "AMNESIA"
  7. ^ H, Weingartner (1983). Forms of cognitive failure. Science. pp. 221:380–2. 
  8. ^ Ribot, T. (1882) Diseases of Memory: An essay in the positive psychology. London: D. Appleton and company.
  9. ^ a b Corkin, S., Milner,B. & Teuber, H. (1968) Further Analysis of the Hippocampal Amnesic Syndrome: 14-Year Follow-up Study on Patient H.M. Neuropsychologia. 6, 215-234.
  10. ^ a b Draaisma, D. (2013). "Neuroscience: Losing the past". Nature 497 (7449): 313. doi:10.1038/497313a. 
  11. ^ Rosenbaum, R. S.; Murphy, K. J.; Rich, J. B. (2012). "The amnesias". Wiley Interdisciplinary Reviews: Cognitive Science 3: 47. doi:10.1002/wcs.155. 
  12. ^ Zola-Morgan S, Squire LR, Amaral DG (1986). "Human amnesia and the medial temporal region: Enduring memory impairment following a bilateral lesion limited to field CA1 of the hippocampus". The Journal of neuroscience : the official journal of the Society for Neuroscience 6 (10): 2950–2967. PMID 3760943. 
  13. ^ Rempel-Clower NL, Zola SM, Squire LR, Amaral DG (1996). "Three cases of enduring memory impairment after bilateral damage limited to the hippocampal formation". The Journal of neuroscience : the official journal of the Society for Neuroscience 16 (16): 5233–5255. PMID 8756452. 
  16. ^ Goodwin DW, Crane JB, Guze SB (August 1969). "Alcoholic "blackouts": a review and clinical study of 100 alcoholics". Am J Psychiatry 126 (2): 191–8. PMID 5804804. 
  17. ^ Parker ES, Birnbaum IM, Noble EP (December 1976). "Alcohol and memory: Storage and state dependency". Journal of Verbal Learning and Verbal Behaviour 15 (6): 691–702. doi:10.1016/0022-5371(76)90061-X. 
  19. ^ a b Erdogan, Serap (2010). "Anterograde Amnesia". Psikiyatride Guncel Yaklasimlar-Current Approaches in Psychiatry 2 (2): 174–189. Retrieved 27 November 2011. 
  21. ^ "memory abnormality." Encyclopædia Britannica. Encyclopædia Britannica Online Academic Edition. Encyclopædia Britannica Inc., 2012. Web. 21 Apr 2012.
  22. ^ Masferrer R, Masferrer M, Prendergast V, Harrington TR (2000). "Grading Scale for Cerebral Concussions" ([dead link]). BNI Quarterly (Barrow Neurological Institute) 16 (1). ISSN 0894-5799
  23. ^ "Dissociative Fugue. Retrieved 7 August 2012". Retrieved 2012-12-22. 
  24. ^ "The Merck Manuals Online". Retrieved 2012-12-22. 
  27. ^ Schacter, D.L., Harbluk, J.L., and McLachlen, D.R. (1984). Retrieval without recollection: an experimental analysis of source amnesia. Journal of Verbal Learning and Verbal Behaviour, 23(5): 593-611.
  28. ^ a b "Shaheen Emmanuel Lakhan: Neuropsychological Generation of Source Amnesia: An Episodic Memory Disorder of the Frontal Brain. Journal of Medicine, Volume 1, Issue 1, 2007". Retrieved 2012-12-22. 
  29. ^ "Types of Amnesia". uwaterloo. Retrieved 9 April 2012. 
  30. ^ Walsh RD, Jr Wharen RE, IV Tatum WO (2011). "Complex transient epileptic amnesia". Epilepsy & Behaviour 20 (2): 410–413. doi:10.1016/j.yebeh.2010.12.026. 
  31. ^ a b Nordquist, C. (2004) What is Amnesia? What Causes Amnesia? Medical News Today. Retrieved from:
  32. ^ a b "Treating Amnesia. Neurology Now. 4(4), pg. 37 (2008)". doi:10.1097/01.NNN.0000333846.54546.f8. Retrieved 2012-12-22. 
  35. ^ Benson DF (October 1978). "Amnesia". Southern Medical Journal 71 (10): 1221–1227. doi:10.1097/00007611-197810000-00011. ISSN 0038-4348. PMID 360401.