EverydayArticle link

How Posterior Cortical Atrophy Is Diagnosed: A Guide for Families and Early-Stage Patients

Posterior cortical atrophy (PCA) is a rare dementia that often strikes in the 50s and 60s, causing visual difficulties rather than memory loss. Because its symptoms mimic eye problems, diagnosis can be delayed. This article walks you through the diagnostic process—what to expect, how to prepare, and how to advocate for a thorough evaluation. There are concrete steps you can take to get clarity and support, even when the path feels uncertain.

Key points

  • PCA is a rare dementia that affects vision first, not memory. It often starts in the 50s or 60s.
  • Diagnosis requires a specialist who understands atypical dementias—often at a university medical center.
  • Keep a detailed symptom journal and bring a family member to appointments.
  • A normal eye exam does not rule out PCA; the problem is in the brain's visual processing areas.
  • Brain MRI showing atrophy in the back of the brain is a key diagnostic clue.
  • Advanced testing like PET scans or spinal taps can confirm if Alzheimer's is the underlying cause.
  • You are not alone—support groups and online communities exist for PCA.

What Is Posterior Cortical Atrophy?

Posterior cortical atrophy is a progressive condition where brain cells in the back of the brain—the parietal and occipital lobes—gradually waste away (atrophy). These regions are heavily involved in processing visual information, so the earliest symptoms are visual, not memory-related. People with PCA may have trouble judging distances, recognizing objects, reading, or navigating spaces, even though their eyes are healthy. This is why the condition is often mistaken for an eye problem at first.

In more than 80% of cases, PCA is actually a form of Alzheimer's disease, but it can also be caused by other neurological conditions such as Lewy body dementia or corticobasal degeneration. The onset is typically in a person's 50s or 60s, much earlier than typical Alzheimer's, which often begins after age 65. Because of this early onset and the unusual symptoms, getting the right diagnosis can take time.

Why Diagnosis Is Challenging

Many people with PCA first see an eye doctor or optometrist, who finds no damage to the eyes. The problem is in the brain's ability to interpret what the eyes see. This disconnect can lead to years of frustration and misdiagnosis. For example, one person was initially treated for epilepsy because of visual disturbances, but the medication didn't help. Another person hid their symptoms for a long time, afraid of what they might mean.

Because PCA is rare—accounting for only 5 to 15% of Alzheimer's cases—many neurologists have limited experience with it. That's why it's important to see a specialist who understands atypical dementias. A neurologist who specializes in vision or dementia, often at a university medical center, can use specific tests to identify PCA.

The Diagnostic Process: What to Expect

The diagnosis of PCA is made through a combination of clinical evaluation, neuropsychological testing, and brain imaging. There is no single blood test or scan that definitively diagnoses PCA, but a careful assessment can rule out other causes and confirm the pattern of brain changes.

First, the neurologist will take a detailed history of symptoms, often asking both the patient and a family member. They'll want to know exactly what visual difficulties you're having—like trouble reading, bumping into things, or difficulty recognizing faces. They'll also check for other cognitive functions like memory, language, and reasoning, which are often relatively spared in early PCA.

Next, they'll perform a neurological exam that includes tests of visual processing, such as asking you to copy a drawing, identify objects, or judge distances. They may also use specialized tests like the "15-item visual object and space perception battery" or the "Birmingham Object Recognition Battery" to pinpoint the type of visual difficulty.

Brain imaging, especially MRI, is crucial. In PCA, the MRI will show atrophy (shrinkage) in the back parts of the brain—the occipital and parietal lobes—while the front parts look relatively normal. This pattern is a key clue. In some cases, a PET scan or spinal tap may be used to look for amyloid plaques, which are the hallmark of Alzheimer's disease. If amyloid is present, it strongly suggests that PCA is due to Alzheimer's.

The Role of the Caregiver in the Diagnostic Journey

As a caregiver, you are an essential part of the diagnostic process. You can help by keeping a detailed log of symptoms: when they started, what makes them worse or better, and how they affect daily life. Write down specific examples, like "last week, he couldn't find the milk in the fridge even though it was right in front of him" or "she has started to miss the chair when she sits down."

You can also help by advocating for a referral to a specialist. If your general neurologist isn't familiar with PCA, ask for a referral to a memory disorders clinic or a neuro-ophthalmologist. Don't be afraid to seek a second opinion. Many people with PCA have been misdiagnosed with anxiety, depression, or even malingering before getting the correct diagnosis.

General caregiving information, not medical advice. Check medications and major care changes with your clinician.

Step-by-step

  1. Schedule an appointment with a neurologist, ideally one experienced in atypical dementias, if you notice visual difficulties (e.g., trouble reading, judging distances, or recognizing objects) but have normal eye exams.

  2. Bring a detailed timeline of visual symptoms and their progression to the first appointment, including specific examples (e.g., 'cannot see the full plate of food,' 'misjudges stairs').

  3. Obtain a comprehensive neuropsychological evaluation that includes tests of visuospatial and visuoperceptual abilities, not just memory.

  4. Request brain imaging (MRI or FDG-PET) to look for atrophy or hypometabolism in the parietal and occipital lobes, and to rule out other causes like stroke or tumor.

  5. Ask the neurologist to order blood tests to exclude reversible causes of visual/cognitive changes (e.g., vitamin deficiencies, thyroid disease, autoimmune conditions).

  6. Seek a second opinion at a dementia specialty center (e.g., Alzheimer’s Disease Research Center) if initial evaluations are inconclusive.

What not to do

  • Do not accept a diagnosis of eye disease if eye exams are normal and symptoms persist.

  • Do not rely on a single memory-focused cognitive screening (e.g., Mini-Mental State Exam) to rule out PCA.

  • Do not delay evaluation waiting for memory loss to appear—PCA often presents without memory issues for years.

Practical tools

  • PCA Diagnostic Checklist

    A printable checklist of PCA-specific symptoms and required referrals (neurology, neuropsychology, brain imaging) to bring to appointments.

  • Symptom Diary Template

    A structured log to record daily visual difficulties (e.g., driving, reading, depth perception) with dates and triggers, for use in clinical evaluations.

  • Clinic Locator for Atypical Dementias

    A curated list of specialty clinics (e.g., UCSF Memory and Aging Center, Mayo Clinic) with known PCA expertise, including contact information.

Discuss with your clinician

Ask your doctor: 'What is the likelihood that my PCA is due to Alzheimer's disease versus another condition like Lewy body dementia or corticobasal degeneration?'

Ask your doctor: 'Would a PET scan for amyloid or a spinal tap help clarify the underlying cause? What are the risks and benefits?'

Ask your doctor: 'Are there any medications that might help with my visual symptoms or slow the progression? What about treatments for Alzheimer's if that is the cause?'

Ask your doctor: 'Should I see a neuro-ophthalmologist or a low-vision specialist? Can you give me a referral?'

Ask your doctor: 'What clinical trials are available for PCA or atypical Alzheimer's? Am I eligible for any?'

Ask your doctor: 'How often should I have follow-up appointments? What changes in symptoms should prompt me to call you?'

Related guides

Sources