Posterior Cortical Atrophy

Posterior cortical atrophy (PCA) is a rare, usually younger-onset form of Alzheimer's that first damages vision processing rather than memory; learn the early signs, why it is often misdiagnosed as an eye problem, and how it is treated.

Last reviewed: October 2026

Most people think of Alzheimer's disease as a disease of memory. But in some people, it starts somewhere else entirely: in the parts of the brain that make sense of what the eyes see. This is called posterior cortical atrophy (PCA), sometimes known as Benson's syndrome.

"Posterior" means the back of the brain; "cortical" refers to its outer layer; "atrophy" means shrinking. The eyes themselves are healthy—it's the brain's ability to interpret what they see that is damaged.

What causes PCA?

The UCSF Memory and Aging Center describes PCA as a rare, visual variant of Alzheimer's disease. In most cases, the brain shows the same amyloid plaques and tau tangles seen in typical Alzheimer's—just concentrated in different areas (see Amyloid and Tau Explained). Less often, PCA is caused by other diseases such as Lewy Body Dementia or Creutzfeldt-Jakob Disease.

A large 2024 international study of 1,092 people with PCA from 36 research centers in 16 countries confirmed the strong link to Alzheimer's. Among people who had brain scans for Alzheimer's proteins, 94% had positive amyloid PET and 97% had positive tau PET. At autopsy, Alzheimer's disease was the main finding in 94% of cases.

Who gets it?

PCA tends to start younger than typical Alzheimer's. In the 2024 study, the average age when symptoms began was about 59, and 60% were women. The Alzheimer's Association notes onset commonly occurs between ages 50 and 65. See Young-Onset Dementia.

How common is it? Estimates vary because PCA is often missed. The Alzheimer's Association cites studies suggesting about 5% of people diagnosed with Alzheimer's have PCA, and possibly as many as 15%.

Early signs

The first symptoms are usually visual and spatial, while memory may be fairly well preserved at first. UCSF and the Alzheimer's Association describe problems such as:

Trouble reading, especially following lines of text
Difficulty judging distances, such as with stairs, curbs or parking
Trouble seeing more than one object at a time, or finding something right in front of you
Difficulty reaching accurately for objects
Sensitivity to bright light or shiny surfaces; trouble seeing in dim light
Problems with spelling, writing and math
Trouble recognizing faces or objects
Difficulty using tools, dressing, or telling moving objects from still ones

As PCA progresses, people may get lost in familiar places, and eventually develop memory, language and thinking problems more like typical Alzheimer's.

Why it's often misdiagnosed

Because the first problems seem to be with vision, many people visit an eye doctor first—sometimes several times. The Alzheimer's Association notes that the eye exam is often normal, and new glasses don't help. Since memory may still be good, dementia may not be considered. Symptoms can also be mistaken for anxiety or depression.

A clue worth knowing: if someone in their 50s or early 60s has worsening "vision problems" that eye exams can't explain, ask whether a neurologist should take a look.

How it's diagnosed

There's no single test. According to UCSF and the Alzheimer's Association, doctors use a combination of:

A detailed history and neurological exam
Neuropsychological testing that focuses on visual and spatial skills
Brain imaging—MRI often shows thinning at the back of the brain; PET scans can show reduced activity there and detect amyloid or tau (see Brain Imaging: MRI, CT and PET)
Spinal fluid or blood tests for Alzheimer's proteins (see Spinal Fluid (CSF) Testing and Blood Tests for Alzheimer's)
Tests to rule out stroke, tumor or other causes

Treatment and support

There's no cure, and no treatment is proven to stop PCA. But much can be done to help:

Medicines: UCSF notes that cholinesterase inhibitors such as donepezil, rivastigmine and galantamine may help symptoms (see Cholinesterase Inhibitors and Memantine). Antidepressants can help with depression, irritability or loss of confidence. Ask a specialist whether newer anti-amyloid drugs (see Lecanemab (Leqembi)) could be appropriate; PCA was not well represented in the main trials.
Occupational and physical therapy can teach new ways to handle daily tasks.
Low-vision strategies: good, even lighting; high-contrast tape on stair edges; uncluttered spaces; talking books, voice assistants and screen readers.
Safety: driving is often affected early because of trouble judging distances. See Driving and Dementia and Home Safety.

Living with PCA

Because PCA often begins in midlife and affects vision first, people may still be working and raising families. They often keep good insight into their difficulties, which can bring frustration and grief. Connecting with others who understand helps. The UCSF Memory and Aging Center lists Rare Dementia Support and online PCA support groups among its resources.

Outlook

UCSF notes that some people with PCA live about as long as people with typical Alzheimer's—on average around 10 to 12 years after symptoms begin—but this varies widely.

Where to get help

Alzheimer's Association 24/7 Helpline: 800-272-3900
NIA ADEAR Center: 800-438-4380

Sources

Not medical advice. This article is general information, not a diagnosis or treatment plan for any individual. Talk with a doctor about your situation.

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