When Vision Fades Before Memory: Understanding Posterior Cortical Atrophy

Most of us have a very specific image in mind when we hear the words "dementia" or "Alzheimer’s." We usually think of short-term memory loss, forgotten names, or repeating stories.

But there is a rarer form of dementia where memory remains sharp in the early stages, while eyesight and spatial awareness quietly begin to fail. This condition is called Posterior Cortical Atrophy, or PCA.

Doctors often call it the "visual variant" of Alzheimer’s disease. It can be confusing for families because the person affected might sound perfectly normal in conversation, yet struggle to navigate their own living room.

Here is a plain-English guide to the symptoms of PCA and how to spot them.

What is PCA?

To understand the symptoms, it helps to know a little bit about geography - brain geography, that is.

Standard Alzheimer’s disease usually starts in the hippocampus, the area responsible for memory. PCA, however, attacks the posterior cortex first. This is the back part of the brain responsible for processing visual information and spatial relationships.

Think of the posterior cortex as the brain's internal GPS and image processor. In PCA, the eyes are usually healthy and "see" perfectly fine. The problem is that the brain cannot make sense of the data the eyes are sending it.

The Early Warning Signs

Because PCA is rare (and often affects people at a younger age, sometimes in their 50s or 60s), it is frequently misdiagnosed as an eye problem. Patients often go through several pairs of glasses or visit multiple ophthalmologists before realising the issue is neurological, not optical.

Here are the most common day-to-day symptoms.

1. Difficulty Reading and Spelling

One of the first signs is often trouble with words on a page. This isn’t just about blurry vision. A person with PCA might feel like the words are "jumping around" or moving. They might lose their place easily while reading a book or struggle to bring the text into focus.

• What to look for: You might notice someone holding a newspaper at odd angles, skipping lines frequently, or suddenly struggling with spelling simple words they used to know.
  

2. Trouble with "Spatial Awareness"

Spatial awareness is your ability to judge where your body is in relation to objects around you. When the back of the brain deteriorates, this judgment fails.

• What to look for: This can look like clumsiness. A person might reach for a coffee cup and miss it entirely, knocking it over. They might struggle to navigate stairs because they cannot judge the depth of the step.
  

3. Driving Difficulties

Because driving relies entirely on judging speed, distance, and lane position, it is often one of the first skills to suffer.

• What to look for: A driver who was previously safe might start drifting out of their lane, struggling to park between lines, or hesitating at intersections because they cannot gauge how far away oncoming cars are.
  

4. The "Ghosting" Effect

People with PCA often experience visual distortions. They might see "ghost" images (double vision) or perceive objects as fragmented.

• What to look for: They might complain that stationary objects look like they are moving. They may also have trouble distinguishing an object from its background (for example, finding a white pill on a white table).
  

5. Difficulty with Complex Tasks (Apraxia)

Later on, the brain struggles to coordinate complex movements based on what it sees. This is known as apraxia.

• What to look for: This often shows up in dressing. A person might struggle to put on a jacket because they can’t figure out which arm goes into which sleeve, or they might repeatedly try to put a shirt on backwards.
  

What About Memory?

This is the key distinction. In the early stages of PCA, memory, insight, and judgment are usually well-preserved.

A person with PCA can often vividly remember what they did yesterday, hold an intelligent conversation, and recount current events. This preservation of memory can, unfortunately, delay diagnosis, as doctors may rule out dementia because the patient seems "too sharp."

Visual	"My glasses aren't working. The words are moving."
Spatial	"I keep bumping into door frames."
Recognition	"I can see the face, but I can't recognize who it is."
Coordination	"I can't seem to get the key into the lock."

The Bottom Line

Posterior Cortical Atrophy is a complex condition that challenges our standard understanding of dementia. It reminds us that the brain does much more than just remember facts (it constructs our reality).

If you or a loved one is experiencing unexplained visual changes that an eye doctor cannot fix, especially combined with clumsiness or reading difficulties, it may be worth discussing a neurological evaluation.

Here’s a checklist you can print or copy to take to your upcoming appointment. I’ve organised it by category so you can clearly show the doctor which areas are being affected. Here's a PDF version for you to download and print:

Doctors Appointment Checklist.pdf

Download PDF • 54KB

__________________________________________________________________________________

Doctor’s Appointment Checklist: Visual & Spatial Symptoms

Patient Name: ___________________________ Date: ___________________________

Instructions: Check the boxes next to any symptoms you have noticed. Try to write down a specific example for each one you check, as this helps the doctor understand exactly what is happening.

1. Reading and Writing Issues

These are often the earliest signs and are frequently mistaken for a need for a new eye prescription.

• [  ] Text appearing to move or "jump" (Lines of text seem to swim or shift while reading)

• Example: __________________________________________________

• [  ] Getting lost on the page (Skipping lines or unable to find the place after looking away)

• Example: __________________________________________________

• [  ] New difficulties with spelling (Struggling to spell simple words that were previously known)

• Example: __________________________________________________

2. Spatial Awareness and Navigation

Issues with judging where the body is in relation to the world.

• [  ] Reaching and missing (Reaching for an object, like a cup, and missing it or knocking it over)

• Example: __________________________________________________

• [  ] Bumping into things (Walking into door frames or furniture that is clearly visible)

• Example: __________________________________________________

• [  ] Trouble with depth perception (Uncertainty when stepping off curbs or walking down stairs)

• Example: __________________________________________________

3. Visual Distortions

Problems with how the brain interprets what the eyes see.

• [  ] Difficulty with contrast (Trouble seeing light objects on light backgrounds, like milk in a white cup)

• Example: __________________________________________________

• [  ] Sensitivity to light or glare (Bright lights seem unbearable or cause confusion)

• Example: __________________________________________________

• [  ] Double vision or "ghost" images (Seeing more than one of an object)

• Example: __________________________________________________

4. Motor Skills and Dressing (Apraxia)

Difficulty coordinating movements despite having the physical strength to do them.

• [  ] Trouble with clothing (Putting clothes on backward, inside out, or getting stuck in sleeves)

• Example: __________________________________________________

• [  ] Difficulty using common tools (Struggling to use a key, scissors, or remote control)

• Example: __________________________________________________

5. Driving Changes (If applicable)

• [ ] Staying in the lane (Drifting to one side or driving over the centre line)

• Example: __________________________________________________

• [ ] Judging distance (Braking too late or too early, or feeling unsafe making turns)

• Example: __________________________________________________

6. Important Note on Memory

Doctors often associate dementia primarily with memory loss. It is important to clarify this point.

• [  ] Memory is generally preserved (I remember recent conversations, events, and appointments well, despite these visual issues.)

• [  ] Insight is preserved (I am aware that I am having these problems and they are frustrating me.)

Questions to Ask the Doctor

1. Could these symptoms be neurological rather than just an eye problem?

2. Would a referral to a neurologist or a neuro-ophthalmologist be helpful?

3. Are there specific brain scans (like an MRI or PET scan) that look at the back of the brain?