What is posterior cortical atrophy?

Posterior cortical atrophy, or PCA, is a gradual, progressive loss of the outer layer of the brain at the back of the head, the area that processes what we see. The Alzheimer's Association explains that its most common symptoms are visual, that it usually begins between ages 50 and 65, and that in many people it shows the same plaques and tangles as Alzheimer's disease, in a different part of the brain.

The most common symptoms are visual: trouble reading a line of text, judging distances, telling moving objects from still ones, seeing more than one object at a time, and using tools or everyday objects. The Alzheimer's Association adds that some people have hallucinations, trouble with math or spelling, or anxiety. Memory is usually not markedly affected early on, though it can be in later stages.

Usually, yes, though experts still debate whether it is a distinct disease. A 2024 study in The Lancet Neurology of 1,092 people with PCA across 16 countries found Alzheimer's disease was the most frequent diagnosis at autopsy, in 94 percent, and amyloid PET scans were positive in 94 percent. In some people the brain changes instead resemble other diseases, such as dementia with Lewy bodies.

Doctors combine neuropsychological tests, blood tests, brain scans and a neurological exam, and rule out stroke, tumor and other causes. The Alzheimer's Association says clues include visual problems that come on gradually while the eyes test normal and memory is preserved, and onset between 50 and 65. Misdiagnosis is common because people often see an eye doctor first, whose usual exam finds nothing wrong.

There is no treatment known to slow or stop posterior cortical atrophy. Because it often resembles Alzheimer's, the Alzheimer's Association notes that drugs used to temporarily ease Alzheimer's symptoms have been suggested, but their benefit is not proven. Some people may be helped by treatment for depression or anxiety, though the overall benefits and risks are not established, so discuss options with a specialist.