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Retrograde Amnesia: Causes and Types

Retrograde amnesia (RA) is a type of amnesia in which a person can’t remember the events that happened right before the amnesia occurred.

There are many events that can lead up to this type of amnesia. For example, someone may have suffered a stroke, hypoxia, or cranial trauma. Below, we’ll talk more about what RA is as well as what causes it.

Types of Brain Damage That Can Lead to Retrograde Amnesia

retrograde amnesia

If someone damages the Wernicke’s or Broca’s areas of the brain, it can lead to memory loss of language.

This is just one example. Here are the common types of brain damage that can lead to retrograde amnesia:

  • Hypoxia: Happens when the brain is not getting enough oxygen.
  • Cranial Trauma: A blow to the head can cause people to develop this type of amnesia.
  • Cerebrovascular Accident: Strokes, which are quite common, can be a cause.
  • Tumor: If a tumor presses against a certain part of the brain, it can lead to memory loss.

Remember that with this type of amnesia, people have difficult remembering what happened right before the incident happened.

They may still have their long-term memories, and can make new memories. However, the ones right before the accident or disease are gone.

Bottom Line: Some of the type of brain damage that can lead to retrograde amnesia include tumors, strokes, cranial trauma, and hypoxia.

What is Ribot’s Law?

Ribot’s Law states that a patient is more likely to lose a memory that’s closer to an accident rather than lose a distant memory.

This explains why people with RA can’t remember what led up to the event or disease.

Bottom Line: Ribot’s Law states that, following an accident, you’re more likely to lose new memories rather than old ones.

Types of Retrograde Amnesia

There are many types of retrograde amnesia, including:

  • Temporally Graded Retrograde Amnesia: With this type, the patient will be able to remember most of the events that led up to the accident.
  • Pure Retrograde Amnesia: This type of amnesia happens whenever the patient cannot remember the events leading up to the accident.

With PRA, the patient can learn new things, however, they can’t recall recent events.

This shouldn’t be confused with peritraumatic amnesia. This type happens because of mild head trauma and is different than RA.

Bottom Line: In some cases, patients will eventually remember the events leading up to the accident (as in temporarily graded). With pure RA, this doesn’t happen.

Traumatic Brain Injury

During a traumatic brain injury, such as a blow to the head, the brain moves violently within the skull, harming neural tissue in the process.

The degree of RA that you experience will depend on the force of the impact, as well as the location.

One subgroup of people who are susceptible to traumatic brain injuries are football players. This high-contact sport causes the brain to bounce around within the skull, leading to damage.

There’s a lot of evidence to support the theory that severe blows to the head can lead to retrograde amnesia.

Bottom Line: A traumatic injury can cause RA, and comes in many forms. For instance, it can happen during a car accident or during a high-impact sport like football.

The Link Between Nutritional Deficiencies and RA

There’s some evidence to suggest that people who are alcohol-dependent are at a higher risk of developing RA.

Another type of deficiency that could cause it is thiamine deficiency. Thiamine is vitamin B1 and is essential for optimal health.

It’s been shown that chronic alcohol use can decrease the volume of the left and right hippocampus, thus, hindering memory.

In a nutshell, if a person’s diet consists of mainly hard alcohol, and they aren’t getting the nutrients their body needs, then it can lead to retrograde amnesia.

Bottom Line: If someone isn’t getting enough thiamine (vitamin B1), and they’re alcohol-dependent, it could make them more susceptible to RA.

Infections

In some cases, the onset of RA can be caused by brain infections. Normally, microbes have difficulty getting into the brain because of the blood-brain barrier.

But when they do cross over, it can lead to many different types of brain damage (including encephalitis).

There have been cases in which a brain infection led to retrograde amnesia. Treating a brain infection will depend entirely on the type of microbe as well as where it’s located in the brain.

Bottom Line: If a microbe passes the blood-brain barrier, it can lead to a brain infection. Certain brain infections can lead to RA.

Diagnosing Retrograde Amnesia

RA can affect a person’s memory to different degrees. To diagnose someone with this brain condition, doctors will use a variety of tests.

The first type of test involves testing a person’s knowledge of places or events. The problem with this retrograde amnesia test is that people’s knowledge varies.

For this reason, a more accurate approach might be to use an Autobiographical Memory Interview (AMI).

With this test, doctors will ask the person about their personal life- job, family, friends, etc. This is usually good enough to determine if a person’s memory has been affected.

Finally, doctors can perform an MRI or CT scan, both of which are effective at detecting physical changes in the brain.

Bottom Line: Diagnosing RA involves a variety of procedures and diagnostic methods. The main ones include an Autobiographical Memory Interview (AMI), an MRI, or a CT scan.

Spontaneous Recovery

In some cases, a person with retrograde amnesia may spontaneously recover. Researchers aren’t exactly sure why this happens, but it has been observed.

An important thing to note is that memory cannot be recovered with reminder treatment. With reminder treatment, people will try to remind the person with RA about their past.

But many studies show that re-exposing these patients to past personal information has little to no bearing on their ability to remember.

Bottom Line: In some cases, a person with this condition may spontaneously recover. Reminder treatment, or reminding a person with RA about their past, won’t help them remember.

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