Introduction[edit | edit source]
Simply defined as the profound loss of memory, amnesia involves a difficulty in learning new information or remembering past events. It can result broadly from psychological or neurological factors. Amnesia due to neurological factors (also known as neurological amnesia) is characterized by a loss of declarative memory i.e. memory dealing with conscious knowledge of facts and events, while non-declarative memory (dealing with knowledge unconsciously acquired) is preserved. It is associated with damage to the hippocampus and medial temporal lobes.
On the other hand, amnesia caused by psychological factors, otherwise known as functional amnesia: is not as common as neurological amnesia, is a psychiatric disorder with no known underlying damage to a brain structure and commonly results from emotional trauma.
Amnesia can have profound incapacitating effects on individuals, affecting their quality of life and leaving them dependent on others.
Types of Amnesia[edit | edit source]
- Retrograde amnesia (RA) is the partial or total loss of memories acquired before onset of the amnesia. Memory recall can be achieved in these patients by exposing them to important elements or articles from the past. Areas of the brain damaged in RA are the temporal lobes and prefrontal cortex.
- Anterograde amnesia (AA) is described as the inability to form new memories. It may result in decreased attention and inaccurate perception.
- Dissociative amnesia (DA) formerly known as pychogenic amnesia, belongs to a group of conditions referred to as dissociative disorders. It is a form of memory loss where one cannot remember important information about their life. The impairment may be thematic, that is affecting a specific area of the patient's life or general, affecting a large part of their identity. DA is not caused by underlying medical problems but primarily from stress caused by traumatic events like war, abuse, accidents or disasters that were either experienced or witnessed. Memory loss in this case is often shortlived and may return suddenly and completely either on its own or after being triggered. Also, medically induced amnesia often leads to anxiety whereas, patients with DA express no fuss over their loss of memory.
- Post traumatic amnesia (PTA) is a transitory state of memory loss occuring from the onset of a traumatic brain injury to the return of orientation and persistent memory for events. It is characterised by disorientation or mental confusion that is obvious to others, a defective memory and cognitive disturbance, although behaviour within this period may be normal. PTA may extend from a few minutes to several weeks or months and how long it lasts is a strong predictor on the severity of traumatic brain injuries.
- Infantile amnesia (IA) has been suggested to be due to the underdevelopment of the infant brain preventing memory consolidation or retrieval. It is the inability of adults to remember personal memories that occured during the first 2-3 years of life. This differs from childhood amnesia which is the inability to recollect events up to the age of seven.
- Transient global amnesia (TGA) refers to a benign amnestic syndrome which often has good prognosis as it is short-lived, resolving within 24hours. The condition is characterised by an occurence of anterograde and retrograde amnesia during its course.
Causes of Amnesia[edit | edit source]
The causes of amnesia are largely attributed to being acquired in adulthood, although they may rarely occur at birth and in infancy. Causes may include:
- Traumatic head injury
- Hypoxia or anoxia
- Viral infections
- Alcoholic Korsakoff's syndrome
- Brain tumours
Assessment[edit | edit source]
See physiopedia page on Galveston Orientation &Amnesia Test on assessment of amnesia.
Management of Amnesia[edit | edit source]
The quality of life of individuals with amnesia can be improved with:
- The aid of digital devices to set reminders
- Cognitive behavioural therapy
Physiotherapy[edit | edit source]
- It is also important to be knowledgeable about amnesia and its types to aid referral to the appropriate health professional once it is recognised in patients.
References[edit | edit source]
- Allen RJ. Classic and recent advances in understanding amnesia. Version 1. F1000Res. 2018; 7: 331.
- Shrager Y, Squire LR. Amnesia. Scholarpedia 2008; 3(8): 2789 (Accessed 16/07/2021 from: http://www.scholarpedia.org/article/Amnesia#Functional_amnesia)
- The Human Memory. Retrograde Amnesia. Available from: https://human-memory.net/retrograde-amnesia/ (accessed 22 July 2021)
- Cantu RC. Posttraumatic retrograde and anterograde amnesia: pathophysiology and implications in grading and safe return to play. Journal of athletic training. 2001 Jul;36(3):244.
- Cleveland Clinic. Dissociative Amnesia. Available from: https://my.clevelandclinic.org/health/diseases/9789-dissociative-amnesia#:~:text=What%20is%20dissociative%20amnesia%3F,%2For%20identity%20(general). (accessed 22nd July 2021)
- Cho MJ, Jang SH. Relationship between post-traumatic amnesia and white matter integrity in traumatic brain injury using tract-based spatial statistics. Scientific Reports. 2021 Mar 25;11(1):1-8.
- Spiteri CJ, Ponsford JL, Roberts CM, McKay A. Aspects of Cognitive Impairment Associated with Agitated Behaviour during Post-traumatic Amnesia. Journal of the International Neuropsychological Society. 2021 May 17:1-9.
- Johnstone EC, Owens DC, Lawrie SM. Companion to psychiatric studies e-book. Elsevier Health Sciences; 2010 Jul 26.
- Alberini CM, Travaglia A. Infantile amnesia: a critical period of learning to learn and remember. Journal of Neuroscience. 2017 Jun 14;37(24):5783-95.
- Bouyeure A, Noulhiane M. Memory: Normative development of memory systems. InHandbook of Clinical Neurology 2020 Jan 1 (Vol. 173, pp. 201-213). Elsevier.
- Liampas I, Raptopoulou M, Siokas V, Tsouris Z, Brotis A, Aloizou AM, Dastamani M, Dardiotis E. The long-term prognosis of Transient Global Amnesia: a systematic review. Reviews in the Neurosciences. 2021 Jan 29.
- Human Memory. Anterograde Amnesia. Available from: https://human-memory.net/anterograde-amnesia/ (accessed 22nd July 2021).