Bizarre Visual Symptoms Point To Alzheimer’s Down The Road

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. In fact, 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 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.
• 47 percent 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: “It’s critical that doctors learn to recognize the syndrome so patients can receive the correct diagnosis, counseling, and care.

“From a scientific point of view, we really 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 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.