Retrograde Amnesia

What is Retrograde Amnesia?

Retrograde amnesia is a disorder that affects the memory (storing and retrieving capabilities of the brain) along with disturbing the formation of memories happening before the onset of amnesia. It involves memory loss of facts where skills remain unaffected with one forgetting any situation, event or factual memory affecting the episodic memory and declarative memory.

This condition shows an impairment of autobiographical memory that consists of recollection of a series of memories depending upon the personal experiences and descriptive knowledge. This disorder is opposite to anterograde amnesia that is characterized by a deficit in combining new information subsequently to a traumatic event.

Types

Focal Retrograde Amnesia

It occurs when a person experiences no symptoms of anterograde amnesia. Other names of this type are pure retrograde amnesia and isolated retrograde amnesia.

Temporally Graded Retrograde Amnesia

It is the most common form in which the most recent memories get affected first, and oldest memories remain safe. This whole process is called Ribot’s law.

Dissociative (psychogenic) Amnesia

It is the exceptional type where any damage to the brain does not cause dissociative amnesia occurring due to emotional shock. It often happens due to violent trauma or crime with a psychological response where one is unable to recall things occurring before the traumatic event.

Causes

Hippocampus

It is the important portion of the brain that is responsible for storing and encoding all kind of information without any damage or defect resulting in the amnesia.

Diencephalon

Diencephalon is the major posterior part of the forebrain transferring sensory information between the cerebral hemispheres while regulating the function of the peripheral nervous system.

Temporal lobes

Temporal lobes are present in the cerebral cortex regulating the speech, language, visual processing and hearing attributes in a person. Any trauma or accidental removal of these lobes may result in RA.

Thiamine deficiency

Excessive alcohol consumption or malnutrition causes thiamine deficiency resulting in Wernicke encephalopathy developing into a chronic condition named korsakoff psychosis (present in both anterograde and retrograde amnesia).

Encephalitis

Viral infection (like herpes simplex) causes inflammation in the brain causing damage to the part of the brain that stores memory.

Traumatic brain injury

Serious injury to brain damages the memory storing part of it leading to retrograde amnesia. Some mild brain injuries may cause a concussion.

Stroke

A stroke can affect verbal memory as well as the visual memory causing dementia.

Alzheimer’s disease

This disease describes the loss of memory and the intellectual capacity of an individual forming dementia promoting the worsening condition of retrograde amnesia.

Seizures

Seizures are changes in the electrical activity of the brain that damages the brain and memory (storing part). These affect the temporal and frontal lobes of the brain becoming the common cause of memory loss in the patient with epilepsy.

Cardiac Arrest

Cardiac arrest is a condition in which heart ceases to beat causing people to stop breathing. As a result, the brain lacks oxygen for a few minutes that lead to severe brain damage that can cause retrograde amnesia.

Psychologically Disturbing Events

Recent studies suggest that regular mental stress and emotional fear can stimulate the onset of retrograde amnesia. As per the earlier discussion, it is a fact that focal retrograde amnesia does not have any neurological basis of occurrence.

Korsakoff Syndrome

The excessive alcohol abuse and malnutrition promote the depletion of thiamine in the brain where vitamins with soluble properties are required to control the proper functioning of the brain. The dominance of hard alcohol over nutritional food gradually damages the brain and causes amnesia.

Infectious Conditions

Viruses and bacteria are the most common agents that cause infection in the brain, spinal cord, and its associated parts. They penetrate several regions of the brain resulting in inflammation. A range of disorders can arise due to the infection and region of infection. Some of them are:

  • Myelitis
  • Encephalitis
  • Abscess
  • Meningitis

Psychiatric Treatment

Psychological disorders seek psychiatric treatment which sometimes generates adverse effects on the brain and triggers the induction of retrograde amnesia. ECT (electroconvulsive treatment) is one of those treatments that involves the process of passing electric currents through the brain to control the convulsions. It applies to them who are extremely depressed and not responding to antidepressants. This method contains benefits along with short-term memory loss as a drawback.

Surgery

Previous surgery in the brain may lead to retrograde amnesia and inactivation of some parts of the organ. To cure the existing brain condition, experts sometimes remove the hippocampus and temporal lobes that cause the elimination of episodic and declarative memory.

Symptoms

  • Long-term memory loss
  • Difficulty in recollection of non-verbal information
  • The incorrect way of sentence formation while speaking
  • Forgetting names, places, people, facts and general knowledge from before the onset of amnesia
  • Inability to recall autobiographical information
  • Improper organization and categorization of verbal content

Retrograde Amnesia V/s Anterograde Amnesia

Individuals with anterograde amnesia get in trouble making new memories while people with retrograde amnesia face trouble accessing memories from the past.

Diagnosis

Diagnosis process for RA involves the analysis of possible cause, symptoms and full-fledged medical examination.

  • Imaging Tests: CT scan and MRI scan help in the detection of brain injuries and abnormalities evaluating any internal brain injury.
  • Neurological examination: This examination involves the analysis of sensory neuron and motor neurons such as reflexes and nerves response. It reviews the health and medical history of the patient.
  • Cognitive tests: These tests are carried out to evaluate the short-term, and long-term memory. It involves a guided set of questionnaire and tasks. Another test known as TYM (test your memory test) includes minimum ten tasks like calculation, verbal fluency, copying a sentence, semantic knowledge, and recall ability.
  • Blood tests: Blood tests are performed to assess any deficiency or infection.
  • Electroencephalogram: EEG (Electroencephalogram) is a technique to examine the electrical activity in the brain.

Treatment

Medications

The treatment of RA by medical interventions is effective, but they vary from an individual to another depending on the underlying situation and stage. Some of the treatment options are:

  • Using Diuretics, anti-seizure drugs, and surgical resection to lower the brain tissue damage
  • Anti-biotics, steroids, and anticonvulsants used to control the bacterial infection in the brain
  • Antiviral drugs to control the infections caused by herpes viruses
  • Supplementation of thiamine by intramuscular/intravenous injection
  • Maintain adequate oxygen and blood supply

Psychotherapy

Psychotherapy involves regular personal interaction with a psychotherapist to seek a change in the pattern of behavior, and thoughts. It includes diverse methods of psychology to improve the lost memories and mental health.

Occupational Therapy

Occupational therapy includes the learning of new information and replacement of lost memories by developing strategies to make it easy to learn new information.

Prognosis

Prognosis fluctuates according to the condition. It might get cured, worse or remain the same for the whole life. An amnesia patient needs extra care and proper therapy. The better outcome also depends on the support of family members to the patient.

References

  1. https://www.healthline.com/health/retrograde-amnesia#causes
  2. https://blog.cognifit.com/retrograde-amnesia/

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