Amnesia

Did you know?

• Transient global amnesia (TGA) typically affects men aged 50-80 years-old
• 23-65% of murderers claim amnesia after committing their crime
• 15% of people with head injuries will suffer memory loss

Causes of amnesia

Amnesia is caused by injury or damage to the brain from trauma, disease, infection, reduced blood flow (stroke) or the misuse of alcohol and drugs. The common association to amnesia and memory loss is from brain injuries after a blow to the head or from degeneration of brain cells (as in dementia).

With head injury and disease, brain cells are lost and cannot be replaced. Car accidents or severe blows to the head cause the most significant amount of brain damage leading to a state of confusion and memory loss.

Infections such as herpes can cause memory loss while malnutrition, drink and drug abuse all deprive the brain of essential nutrients which kill off brain cells and result in loss of memory. Amnesia can also occur after a stroke as the area of the brain that deals with memory function is affected.

Symptoms of amnesia

Someone suffering with amnesia will have difficulty recalling information they have previously learned and/or will find learning new information difficult. Amnesia sufferers can feel disorientated and confused and symptoms can be so severe that they require full-time care.

Typically, amnesia lasts 24-48 hours but severe trauma can extend that period to weeks or months. In cases of dementia (Alzheimer's etc.), memory loss is all but permanent with the patient recalling partial information from their life but in a sporadic and haphazard manner.

There are three main types of amnesia: anterograde amnesia, retrograde amnesia and Korsakoff's psychosis.

Anterograde amnesia – sufferers will have difficulty remembering ongoing events and day-to-day routine. Past memories from childhood or self-awareness are not affected.

Retrograde amnesia – someone with this type of amnesia will have difficulty retrieving memories prior to their head injury or damage to the brain. In the case of accidents, people sometimes never recall the few seconds leading up to their incident.

Korsakoff's psychosis – this is memory loss caused by the misuse of alcohol. Short-term memory is normal but recalling people's names, faces or simple words and stories becomes difficult. Korsakoff's psychosis is a progressive disorder that is accompanied by other neurological problems such as poor coordination.

Other types of amnesia include:

Traumatic amnesia – caused by a blow to the head usually from a road accident and leading to loss of consciousness or coma.

Childhood amnesia – Sigmund Freud put the inability to recall childhood memories down to sexual repression but other experts have linked the problem to areas of the brain involved with memory having not matured properly.

Hysterical amnesia – episodes of psychological trauma can cause this temporary condition whereby the mind finds it difficult to deal with a severe traumatic event and so slows down the memory. Recalling the traumatic event may be possible again after a few days but the memory may remain incomplete.

Diagnosis of amnesia

The diagnosis of amnesia requires a doctor to perform a thorough evaluation to rule out any underlying medical conditions such as Alzheimer's disease, depression or brain tumours. As amnesia affects memory, a family member or close friend may need to accompany the person to answer questions about their medical history.

To determine memory loss, the doctor will ask questions about:

• The type of memory loss suffered (can they recall recent events?)
• At what point the memory loss began and how it's progressed/deteriorated
• Any factors which may have triggered the memory loss (blows to the head, stroke, surgery)
• Family history of neurological problems or disease
• Drug and alcohol use
• History of depression, seizures or cancer
• Any other symptoms such as poor coordination, moods, confusion, language problems

The doctor may also ask questions about common topical knowledge such as the name of the Prime Minister or what year it is. The doctor will also determine the patients recall of personal information such as name, age and address.

A physical examination may then be carried out to check the neurological condition of the patient. The doctor will check reflexes, balance and sensory function (sight and sound tests). Once these preliminary tests have been completed the doctor will be better placed to determine the extent of memory loss and what treatment is required.

The doctor may refer the patient for further diagnostic tests to look for damage or abnormalities in the brain. MRI (magnetic resonance imaging), CT (computerised tomography) or EEG (electroencephalogram) tests may be required. Blood tests may be requested to check for infections, nutritional deficiencies or other problems.

Should the individual have suffered a recent blow to the head then seek emergency treatment immediately. Do not wait and book and appointment to see your GP.

Related Terms

• Forgetting
• Memory loss
• Repression
• Neurological disorder
• Accident trauma
• Head injury
• Concussion
• Cranial 
• Retrograde Amnesia
• Lacunar Amnesia
• Anterograde Amnesia
• Traumatic Amnesia
• Fugue Amnesia
• Childhood Amnesia
• Global Amnesia
• Posthypnotic Amnesia
• Stroke
• Tumour
• Memory Recall