Amnesia Microchapters |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Zehra Malik, M.B.B.S[2]
Amnesia can be divided into two broad groups, retrograde amnesia and anterograde amnesia. Retrograde amnesia is the loss of memory prior to the onset of amnesia and anterograde amnesia is the inability to form new memory. Other types of amnesia are Psychological including repressive amnesia and dissociative fugue, infantile amnesia, neurological amnesia (Alzheimer's disease, Pick's disease), post-traumatic Amnesia, drug-Induced Amnesia, transient global amnesia.Memory can also be divided into two groups depending on the duration, short-term memory and long-term memory.
Types of Amnesia | Main Features |
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Dissociative Amnesia | Temporary, episodic retrograde memory loss without structural brain damage. Cause is psychological in origin. Dissociative Amnesia is also referred to as psychological amnesia. It has variable presentation:
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Transient global amnesia | Sudden episodic loss of anterograde and partial retrograde memory. Usually last less than twenty four hours.[4] |
Post-traumatic Amnesia | Amnesia that follows head trauma could be temporary or permanent. The span of memory loss is uncertain it could present with retrograde, anterograde or combined. Extent of injury and duration of loss of consciousness are important prognostic factors in determining the severity of amnesia. [5] |
Infantile Amnesia | Also known as childhood amnesia. Early childhood memory is lost, usually up to the age of fours year. Influenced by cultural norms and sexual repression.[6] |
Drug-Induced Amnesia | Benzodiazepine are the most common group of drugs that can cause drug-induced amnesia, especially if used with alcohol. Memory loss could be long term or short term.[7] Amnesia is anterograde from the time the drug was introduced and patient has impairment in forming new memories. It is reversible upon discontinuation of the drug. |
Neurological Amnesia | Alzheimer's Disease, Pick's Disease, Parkinson's Disease |
Amnesia in Korsakoff’s Syndrome | Caused by thiamine deficiency due to prolonged alcohol use or severe malnutrition. Anterograde amnesia, retrograde amnesia, and confabulation.[8] |
Selective Amnesia | Certain memory is lost. Patient may forget about certain relationships, talents, events, or traumatic incidents. |
Epileptic Amnesia | Observed in patients with temporal lobe epilepsy.[9] Anterograde amnesia with short-term memory loss. |
Lacunar amnesia | Memory of a particular event is lost. Lacuna mean 'a gap', which refers to leaving 'a gap' in memory.[10] |