Her disorder is mental for the fact it's two types of amnesia: Retrograde and Anterograde.

     Retrograde Amnesia

. What is retrograde amnesia?

Amnesia is a type of memory loss that affects your ability to make, store, and retrieve memories. Retrograde amnesia affects memories that were formed before the onset of amnesia. Someone who develops retrograde amnesia after a traumatic brain injury may be unable to remember what happened in the years, or even decades, prior to that injury.

Retrograde amnesia is caused by damage to the memory-storage areas of the brain, in various brain regions. This type of damage can result from a traumatic injury, a serious illness, a seizure or stroke, or a degenerative brain disease. Depending on the cause, retrograde amnesia can be temporary, permanent, or progressive (getting worse over time).

With retrograde amnesia, memory loss usually involves facts rather than skills. For example, someone might forget whether or not they own a car, what type it is, and when they bought it — but they will still know how to drive.

Retrograde vs. anterograde amnesia

The two main types of amnesia are anterograde and retrograde.

People with anterograde amnesia have trouble making new memories after the onset of amnesia. People with retrograde amnesia have trouble accessing memories from before the onset of amnesia.

These two types of amnesia can coexist in the same person, and often do.

(This is the case with Yin; she has both types of amnesia.)

What are the types and symptoms?

Temporally graded retrograde amnesia

Retrograde amnesia is usually temporally graded, which means that your most recent memories are affected first and your oldest memories are usually spared. This is known as Ribot's law.

The extent of retrograde amnesia can vary significantly. Some people may only lose memories from the year or two prior to having the injury or disease. Other people may lose decades of memories. But even when people lose decades, they typically hang on to memories from childhood and adolescence.

Symptoms include:

not remembering things that happened before the onset of amnesia
forgetting names, people, faces, places, facts, and general knowledge from before the onset of amnesia
remembering skills like riding a bike, playing the piano, and driving a car
retaining older memories, especially from childhood and adolescence
Someone with this condition may or may not be able to make new memories and learn new skills.

Focal retrograde amnesia

Focal retrograde amnesia, also known as isolated or pure retrograde amnesia, is when someone only experiences retrograde amnesia with few or no symptoms of anterograde amnesia. This means that the ability to form new memories is left intact. This isolated memory loss doesn't affect a person's intelligence or ability to learn new skills, like playing the piano.

     Anterograde Amnesia

Overview

Anterograde amnesia refers to a decreased ability to retain new information. This can affect your daily activities. It may also interfere with work and social activities because you might have challenges creating new memories.

Anterograde amnesia is a subset of amnesia. In such cases, the amnesia (memory loss) has already occurred. It's caused by damage to memory-making parts of your brain. In some cases amnesia may be temporary, but in other cases it may be permanent. Some types of therapies can help you cope with this type of memory loss.

Proactive, anterograde, and retrograde amnesia

Anterograde amnesia, according to the Mayo Clinic, is one of the two primary features of amnesia. People with this feature have difficulty making new memories based on experiences and information they come across.

The other feature is called retrograde amnesia. This refers to the inability to remember events and people from your past. It can also cause you to forget well-established daily information, such as what time you go to work.

Proactive amnesia is another term that refers to anterograde amnesia.

Symptoms

Amnesia is sometimes confused with dementia. The latter is a degenerative disease that affects your memory and information about yourself. However, dementia also leads to brain damage that can lead to more cognitive challenges. Such challenges affect everyday functions, such as work and playing sports.

Anterograde amnesia deals more specifically with remembering new information. You may already have difficulty with long-term memories at this point.

Symptoms of anterograde amnesia primarily affect short-term memory processing. This can cause confusion and frustration. For example, someone with this form of amnesia might forget:

someone they've recently met
a new phone number
a recent meal
the names of famous people
newly made changes to a routine, such as school or job changes
Such symptoms differ from those of retrograde amnesia, which may include forgetting information you already knew before amnesia. For example, you might forget reading a book you've read before. Also, the symptoms of anterograde amnesia occur after you've already started experiencing memory loss.

One 2010 study published in NeuropsychologyTrusted Sourcefound that 7 out of 10 patients with anterograde amnesia were capable of temporarily retaining new information. However, a phenomenon called "retroactive interference" occurred. This is when new information interferes with the previously memorized information. For example, you might remember a number, but learn a new number shortly after, which cancels out the original information.

Causes

Overall, amnesia is caused by damage to your brain. This affects memory-making parts of your brain, such as the thalamus. Anterograde amnesia tends to occur after you start experiencing some symptoms of the disease, such as short-term memory loss. It's caused by certain damages to your brain that lead to differences in the way you retain new information.

An MRI test or a CT scan can help your doctor diagnose physical causes of anterograde amnesia. These can help them look for changes or damages to the brain.

How's it treated?

Amnesia is caused by brain damage. There's currently no treatments that can essentially cure amnesia, but instead treatments concentrate on condition management.

Treatment focuses on therapies and techniques that help improve quality of life. Options include:

vitamin B1 supplements, in case of a deficiency
occupational therapy
memory training
technology assistance, such as reminder apps
There are currently no FDA-approved medications to treat amnesia.

Risk factors

Your risk for developing any form of amnesia may increase if you've had one or more of the following:

stroke
seizures
brain surgery
brain injury
brain tumors
history of alcohol abuse
car accident
sports-related injuries
vitamin B1 deficiency
dementia
electroconvulsive therapy (ECT)

Mild brain injuries may lead to short-term memory loss and your symptoms may improve as your brain heals. Moderate to severe injuries can lead to permanent amnesia.