According to the Alzheimer’s Association, more than 7 million people in the United States are living with Alzheimer’s disease. However, not all cases look the same. For some, the early signs of Alzheimer’s show up not as memory problems, but as difficulty understanding what they see. People may struggle to read, lose their place while walking, or bump into furniture, even though their eyes are healthy and their vision is technically normal.

These issues can happen from a condition known as posterior cortical atrophy (PCA). It’s a rare type of dementia that starts in the back of the brain, in the areas that process visual information. PCA is sometimes referred to as Benson’s syndrome or the “visual variant of Alzheimer’s disease.” However, there’s more to it than that. PCA is a brain condition that can be hard to diagnose and often needs a specialist, even though Alzheimer’s is usually the underlying cause.

In this article, we’ll explain what PCA is and what symptoms to watch out for. We’ll also share how doctors make a diagnosis, what causes it, and what treatment options are available.

What Is the Posterior Cortex?

The word “posterior” means the back. The “cortex” is the brain’s thin, outer layer that helps us think, plan, and act. The posterior cortex is the back part of this outer layer — like the rear section of the brain’s control center.

This area includes the occipital lobes and parts of the parietal lobes, which are important for how we see and move through the world:

• The occipital lobe helps the brain process visual information, including shapes, colors, and motion.
• The parietal lobes help us understand where our body is in space, solve problems (like writing or doing math), and see how objects fit together as part of a whole.
• The posterior cortex is the part of the brain that helps turn what we see into meaning. It allows us to recognize faces, follow directions, and navigate the world around us.

What Is Posterior Cortex Atrophy?

The word “atrophy” means shrinking or weakening of a body part over time. When atrophy happens in the brain, neurons (brain cells) in a specific area are damaged or lost.

In PCA, this damage happens in the parietal and occipital lobes — the parts of the brain that help us see, understand what we’re looking at, and move safely through space. This can lead to problems with visual and spatial awareness.

As PCA progresses, the brain has more trouble interpreting visual information from the eyes. Over time, it becomes harder for a person to recognize objects, understand their surroundings, or make sense of what they see, even if their eyes are healthy.

Symptoms of Posterior Cortical Atrophy

The first symptoms of PCA often look very different from those seen in typical Alzheimer’s disease. Instead of memory problems, the first changes usually involve visuospatial awareness, which is how your brain interprets your body’s position or objects in a space.

A person experiencing these symptoms may visit an ophthalmologist (eye doctor) because they think their eyesight is failing. However, routine eye exams often come back normal. This is why an eye specialist is often the first to suggest a neurological exam. They can tell when the vision problem isn’t coming from the eyes themselves but from how the brain is processing what you see.

Common symptoms of PCA include:

• Reading difficulties — Mixing up letters or losing your place while reading
• Spatial and visual problems — Trouble with depth perception, size, light sensitivity, or double vision; bumping into furniture or knocking things over
• Disorientation — Getting lost, even in familiar settings
• Apraxia — Difficulty using tools, writing, or performing tasks with the hands
• Balint’s syndrome — Trouble moving your eyes toward objects, reaching accurately, or seeing more than one object at a time
• Visual hallucinations — Seeing things that aren’t there
• Personality changes — Shifts in mood, behavior, or social interactions

Over time, people with PCA may develop cognitive impairment (trouble thinking) and memory loss. However, these usually appear later. People may also experience anxiety or depression. These feelings can come from the disease itself or from knowing something is wrong but not being able to explain the symptoms. That’s why emotional support is an important part of care from the beginning.

How PCA Differs From Alzheimer’s Disease

The first symptoms of Alzheimer’s disease are usually related to memory loss and confusion. These include difficulty remembering recent events or conversations, or forgetting important dates. This is because in the typical form of Alzheimer’s, the hippocampus (the memory center) is one of the first areas affected. This is the part of the brain responsible for storing and recalling memories.

As the name suggests, in posterior cortex atrophy, a different part of the brain is affected. Since the posterior cortex controls vision and spatial awareness, the early symptoms typically don’t involve memory loss, but these may still occur later. In both PCA and Alzheimer’s disease, the brain can shrink and nerve cells can be damaged, changes that are not seen in a healthy brain.

PCA also tends to begin at an earlier age. Most cases of PCA develop between the ages of 50 and 65, while most cases of Alzheimer’s are in people aged 65 or older. The level of insight can vary between the two diseases as well. In PCA, people are often aware of their visual struggles, at least in the early stages, leading to frustration. People with typical Alzheimer’s disease may notice their symptoms less in the early stages.

Because of this, care for people with PCA often requires a different medical and emotional approach than care for people with typical Alzheimer’s disease.

Causes and Risk Factors for Posterior Cortical Atrophy

Although fewer than 5 percent of people with Alzheimer’s have PCA, up to 80 percent of PCA cases are due to Alzheimer’s. Researchers know this because, in autopsies (exams of the brain after death), they can see harmful proteins called amyloid plaques and neurofibrillary tangles that build up and damage brain cells.

However, Alzheimer’s disease isn’t the only underlying cause of PCA. It can also develop from other neurodegenerative diseases, such as:

• Corticobasal degeneration
• Lewy body disease (also called Lewy body dementia)
• Prion diseases, including Creutzfeldt-Jakob disease and a rare illness called fatal familial insomnia
• Subcortical gliosis

Because PCA is so rare, researchers don’t yet know of any specific risk factors that could contribute to it. However, certain genes that increase the risk for Alzheimer’s — such as the APOE gene — may also increase the risk for PCA.

Diagnosing Posterior Cortical Atrophy

Getting the right diagnosis of PCA can take time. Because the symptoms often involve some level of visual impairment, people usually see an ophthalmologist first. When eye exams look normal, the person may be referred to a neurologist — a doctor who specializes in the brain and nervous system. This pattern is so common that neurology specialists often consider PCA when a person has serious vision problems but normal eye exam results.

Neuropsychological Testing

Doctors will use several tools to help confirm a diagnosis. The first might be neuropsychological testing. These exams will check a person’s memory, attention, language, and thinking skills. People with PCA may do well on memory tasks in the early stages, but they tend to show more difficulty with visual processing or visuospatial challenges. For example, they may struggle to copy shapes or judge where objects are located.

Imaging

Brain scans can give doctors a closer look at what’s happening inside the brain. An MRI scan may show shrinkage in the posterior brain regions.

Other specialized tests include a type of positron emission tomography (PET) that uses a special dye, called fluorodeoxyglucose. These advanced imaging tests can show hypoperfusion, which means the brain is getting less blood flow and using less energy. This often happens in the back parts of the brain and is a strong sign of PCA.

Cerebrospinal Fluid Tests

Doctors may also test cerebrospinal fluid — the fluid that surrounds the brain and spinal cord. This can show changes in proteins like tau and beta-amyloid, which are found in both Alzheimer’s and PCA. These findings — combined with a person’s medical history and clinical features — can help separate PCA from typical Alzheimer’s or other forms of dementia.

Treatment for Posterior Cortical Atrophy

There’s no cure for posterior cortical atrophy at this time. However, treatment and support can help manage symptoms and improve quality of life. Doctors often prescribe the same medicines used for Alzheimer’s disease. These medications don’t cure PCA, but they may help stabilize symptoms, slow progression, and improve daily function.

• Cholinesterase inhibitors, such as donepezil (Aricept), rivastigmine (Exelon), or galantamine (Razadyne)
• Memantine (Namenda)

These are the same drugs used to treat Alzheimer’s disease and may help people with PCA as well.

Supportive care is just as important as medical treatment. Occupational therapy can teach people ways to adapt to visual impairment — for example, by using high-contrast colors on doors and stairs, adding extra lighting, choosing large-print books, or using mobility aids. Speech and physical therapy may help with reading, writing, and movement challenges.

Prognosis of Posterior Cortical Atrophy

On average, people live about 10 to 12 years after symptoms of PCA begin. Over time, many develop memory loss and other symptoms common in Alzheimer’s disease. PCA is a progressive condition, meaning it gets worse over time, but the longer survival period offers people more time to plan ahead.

This planning may include building a trusted care team and documenting legal and financial wishes to help ensure long-term safety and support. With early planning and the right care, people living with PCA and their families can feel more prepared to face the challenges ahead.

Join the Conversation

On myALZteam, people share their experiences with Alzheimer’s disease, get advice, and find support from others who understand.

If you or a loved one has been diagnosed with posterior cortical atrophy, what has your experience been like? Let others know in the comments below.