Retrograde Amnesia


What is Retrograde Amnesia?

Amnesia, in general, is a loss of memory, while retrograde amnesia is just one form of amnesia. Retrograde amnesia renders someone unable to remember events that occurred before the onset of the amnesia, but the individual is capable of forming new memories without a problem. (1)

What does retrograde amnesia affect?

An individual suffering from retrograde amnesia may be unable to recall events in their past, but they are still capable of speech, as well as, performing other daily tasks such as walking, eating, etc. Therefore, retrograde amnesia affects the explicit memory, also called the declarative memory, which is controlled by the hippocampus. Explicit memory can be divided into 2 categories:

Episodic memory

Which is the recollection of people, places and times along with the associated emotions. Basically, episodic memory allows you to recall events in your past, like travelling back in time and re-living particular moments

Semantic memory

This is concrete knowledge about facts and concepts that we learn along the way. For example, your knowledge of the solar system, gravity and objects around you is part of your semantic memory, otherwise, you wouldn’t recognize that you’re staring at a computer screen right now reading this text.

The other parts of memory not affected by retrograde amnesia are the procedural memories which are memories stored over time through repetition. When you first learned to walk, swim or ride a bike, the process was stored in your procedural memory and you can instinctively perform these activities without thinking. A person with retrograde amnesia may not be able to recall ever riding a bike or swimming, but drop them in a swimming pool and they would not drown. (2)

How does retrograde amnesia develop?

The main culprit in the development of retrograde amnesia is the hippocampus, which is like the brain’s random access memory (RAM). Its purpose is to collect information temporarily before sending it to the neurons and synapses for long-term memory storage.

The temporal lobes also assist the hippocampus in the processing of information before sending it to long-term memory, although the temporal lobes are more dedicated to semantic memory. Damage to either of these regions of the brain can cause retrograde amnesia.

Studies suggest that retrograde amnesia is more likely to affect the memory closer to the occurrence which led to retrograde amnesia in the first place. (3)

Causes

The main causes of retrograde amnesia are:

Brain trauma

This can be due to a direct blow to the head that causes the brain to rattle inside the skull, which could also be caused by shaken baby syndrome

Traumatic events

Subconsciously, the brain can repress certain memories due to stress and fear, and this has been seen in trauma victims

Brain infections

Viral, parasitic or bacterial infections.

Other Causes

Other causes include nutrient deficiency, such as in alcohol addicts who don’t take a healthy diet, and also due to some infections such as encephalitis which cross the blood-brain barrier. Medical procedures like surgery can also damage the hippocampus or temporal lobes, leading to the same, and so do other forms of electrical induction. (4)

How severe can retrograde amnesia be?

Retrograde amnesia can be temporary, and the affected individual will begin recalling events in a few days, while some may take months or even years. This is referred to as temporary graded retrograde amnesia. When the individual is completely unable to recall events, this is called pure retrograde amnesia and can be seen in patients suffering from disorders such as Alzheimer’s disease.

Types

There are different types of retrograde amnesia known, such as:

  • Pure retrograde amnesia,
  • Temporally graded retrograde amnesia,
  • Focal retrograde amnesia,
  • Isolated retrograde amnesia.

Retrograde amnesia vs. Anterograde amnesia

Retrograde amnesia vs. anterograde amnesia

Retrograde amnesia vs. anterograde amnesia

Retrograde amnesia is a loss of memory before the trauma to the brain occurred, for example, without being able to remember things from the past, even though new memories can be created.

Anterograde amnesia on the other hand is a loss of memory after the trauma to the brain occurred, without being able to form new memories even though past memories have not been affected. Both retrograde and anterograde amnesia can be temporary or permanently. (5)

Treatment

The treatment of retrograde amnesia is different for each patient as it is mostly individualized based on the specific underlying cause which led to retrograde amnesia on the first place. (6)

Trauma

In cases of any traumatic injury, anti – seizure medications along with diuretics or even surgical resection can help minimize the brain damages due to brain trauma. A proper support, especially a proper oxygenation and blood supply are very important.

Infection

In cases of an infection, antibiotic treatment along with anti – seizure medications and steroids can help prevent the infection from spreading to other brain parts as well as it will help treat the infection. In cases of a viral infection, antiviral medications are necessary.

Alcohol

In cases of alcohol and drug abuse, patients should be supported in order to quit alcohol and drug abuse as well as about all the negative effects on the health.

Nutrition

Proper nutrition along with supplement vitamins and minerals can help recover faster in cases of retrograde amnesia.

Psychotherapeutic

Psychotherapeutic techniques are also a part of retrograde amnesia treatment which can be very beneficial especially when retrograde amnesia is caused by a traumatic event.

Occupational Therapy

Occupational therapy is a branch of therapy which aims to rehabilitate an individual into resuming their regular activities. Various physical, mental and social factors may hinder an individual’s ability to do the things that matter, and occupational therapy is used to address all of these problems, allowing the individual to return to their normal life and regain the memory as much as possible.

REFERENCES:

  1. Amnesia Available at: http://www.en.wikipedia.org/wiki/Amnesia
  2. Retrograde Amnesia Available at: http://www.en.wikipedia.org/wiki/Retrograde_amnesia#Diagnosis_and_treatment
  3. Retrograde Amnesia Available at: http://www.human-memory.net/disorders_retrograde.html
  4. Retrograde Amnesia Causes Available at: http://www.hxbenefit.com/retrograde-amnesia.html
  5. What is the difference between retrograde amnesia and anterograde amnesia? Available at: http://www.improvememory.org/memory-loss/retrograde-vs-anterograde-amnesia
  6. 9 Methods for treating amnesia Available at: http://www.psychologytoday.com/blog/the-resilient-brain/201406/9-methods-treating-amnesia

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