Bizarre Visual Symptoms Point To Alzheimer’s Down The Road

What if your world began to blur—not from failing eyesight, but because your brain could no longer make sense of what your eyes were seeing? Imagine struggling to read a sentence, recognize a loved one’s face, or judge how far away the curb is—all while your memory remains perfectly intact. This is the eerie, often-overlooked early warning sign of a rare neurological syndrome known as posterior cortical atrophy (PCA). And in a groundbreaking global study, researchers have revealed a chilling truth: this visual disturbance may be a hidden first clue to Alzheimer’s disease.

Key Takeaways

• PCA Is Often Misdiagnosed: Visual symptoms like difficulty reading, depth perception issues, or face blindness may be mistaken for eye conditions, delaying an accurate diagnosis by years.

• Strong Link to Alzheimer’s: In the largest study of PCA to date, 94% of patients with PCA exhibited Alzheimer's pathology, making it a potential early indicator of the disease.

• Women Are Disproportionately Affected: 60% of PCA patients in the study were women, highlighting a need for further research into gender-based vulnerability.

Can’t Read This Clearly? It Might Not Be Your Eyes—It Could Be Your Brain

Have you ever heard of posterior cortical atrophy? If not, you’re not alone. It’s a rare neurological syndrome that features some pretty unusual visual symptoms. These include difficulties in recognizing people’s faces, making out objects in pictures, reading, and judging distances.

Though rare, these symptoms occur in up to ten percent of cases of Alzheimer’s disease. And, as a new study shows, those with the condition will almost certainly go on to be diagnosed with Alzheimer’s or some other form of dementia. What’s worse, posterior cortical atrophy (PCA) is often hard for many eye doctors to accurately diagnose during a normal vision exam.

Here’s what you need to know…

The eyes have been called a window into the brain, so it’s no surprise that all parts of the visual system may be affected by Alzheimer’s disease, including the optic nerve and the retina.

What’s up for debate is when the visual problems begin and why…

Visual Problems in Alzheimer’s Disease

The classic view of Alzheimer’s pathology is that brain regions directly involved with the visual system are only affected relatively late in the disease, but that’s not the case with posterior cortical atrophy.

With PCA, visual problems come first, before any memory lapses. The tell-tale symptoms of Alzheimer’s disease—the memory and language difficulties—follow well behind the visual problems caused by posterior cortical atrophy. This is because PCA first affects the back of the brain, where visual and spatial information is processed.

Recently, a large team of international researchers, led by UC San Francisco, completed the first large-scale study of PCA. Their findings are shocking to say the least…

PCA Predicted Dementia in Every Case

The international research team obtained data for 1,092 individuals who were evaluated at 36 research centers in 16 countries. The average age of patients when symptoms first appeared was 59, several years younger than the typical memory symptoms of Alzheimer’s. What’s more, a whopping 60 percent of the study participants were women.

The research team found PCA overwhelmingly predicts Alzheimer’s, with 94 percent of patients displaying evidence of Alzheimer’s pathology. The remaining six percent had other forms of dementia, such as Lewy body disease and frontotemporal lobar degeneration. In contrast, 70 percent of patients with memory loss have Alzheimer’s pathology.

A challenge of diagnosing PCA is that many patients will have a normal eye exam, however, they will still struggle to judge distances, distinguish between moving and stationary objects, and complete tasks like writing and retrieving a dropped item.

What’s more, most patients with PCA still have normal memory recall and cognition early on, but by the time of their first diagnostic visit - an average of 3.8 years after symptom onset – that has changed. These patients often experience mild or moderate dementia with deficits in memory, executive function, behavior, speech, and language.

The study discovered that the two hallmarks of Alzheimer’s were both prominent in the cerebrospinal fluid, with amyloid beta testing positive in 81 percent of patients and tau in 65 percent. In brain scans, the figures were 94 percent and 97 percent, respectively.

Unable to Draw or Copy Simple Diagrams

In their study, the international research team found the following symptoms of those with PCA:

• 61 percent demonstrated “constructional dyspraxia,” an inability to copy or construct basic diagrams or figures.

• 49 percent had a “space perception deficit,” difficulties identifying the location of something they saw.

• 48 percent had “simultanagnosia,” an inability to visually perceive more than one object at a time.

• ent faced new challenges with basic math calculations.

• 43 percent had problems reading.

Delay in Diagnosis

Neuroscientist Marianne Chapleau, first author of the study published in the journal The Lancet Neurology in February, explained, saying, “We need more awareness of PCA so that it can be flagged by clinicians.

“Most patients see their optometrist when they start experiencing visual symptoms and may be referred to an ophthalmologist, who may also fail to recognize PCA. We need better tools in clinical settings to identify these patients early on and get them treatment.”

Senior author Gil Rabinovici, M.D., added: “Doctors must learn to recognize the syndrome so patients can receive the correct diagnosis, counseling, and care.

“From a scientific point of view, we need to understand why Alzheimer’s is specifically targeting visual rather than memory areas of the brain. Our study found that 60 percent of patients with PCA were women — better understanding of why they appear to be more susceptible is one important area of future research.”

How To Diagnose PCA

If you’re concerned that you or a loved one might have PCA, talk to your primary care physician and ask for a referral to a neuro-ophthalmologist.

To diagnose posterior cortical atrophy, a specialist typically reviews the patient's medical history, symptoms and conducts a physical and neurological examination. Several tests may be used to help diagnose the condition, including:

• Neuropsychological tests: These assess cognitive skills and may include questions about memory, language, and problem-solving abilities.

• Spinal fluid test: This test can measure amyloid and tau proteins that are the hallmark of Alzheimer's disease, which is the most common cause of PCA.

• Blood tests: These may be conducted to check for vitamin deficiency, thyroid disorders, and other conditions that may be causing the symptoms.

• Brain imaging: Magnetic resonance imaging (MRI), fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging, or single-photon emission computerized tomography (SPECT) can provide visual images of brain activity, measure blood flow to regions of the brain, and demonstrate hypometabolism, which can help in the diagnosis.

In addition to these tests, an ophthalmology exam may be performed to rule out other vision-related conditions that could be causing the symptoms.

Here’s the most important message: If you’re worried about PCA, it’s important to consult a neurologist or a neuro-ophthalmologist for an accurate diagnosis, as PCA is often initially perceived as an eye problem due to its visual symptoms.

Summary

Posterior cortical atrophy (PCA) is a rare neurological condition that primarily affects visual processing before any memory issues arise. In a large international study led by UC San Francisco, researchers found that 94% of PCA patients showed signs of Alzheimer’s pathology. Often misdiagnosed due to its visual symptoms and normal eye exams, PCA commonly delays appropriate care. The disorder affects the back of the brain, impairing spatial awareness, reading, and facial recognition. Most patients are women, and they are typically diagnosed around age 59. Early recognition by neuro-ophthalmologists is critical for effective diagnosis and management.

Frequently Asked Questions

What is posterior cortical atrophy (PCA)?

PCA is a rare neurological disorder that impairs the brain’s ability to process visual information, often preceding memory issues linked to Alzheimer’s.

How is PCA different from typical Alzheimer’s disease?

Unlike classic Alzheimer’s, PCA starts with visual and spatial processing problems rather than memory loss.

Can PCA be detected with a regular eye exam?

No. Many PCA patients have normal eye exams, making diagnosis difficult without neurological evaluation.

What are early warning signs of PCA?

Trouble reading, judging distances, recognizing faces, or copying shapes may be early symptoms.

How is PCA diagnosed?

Diagnosis involves neuropsychological tests, brain imaging, cerebrospinal fluid analysis, and ruling out other vision problems.