Posterior Cortical Atrophy, or PCA, is a rare form of Alzheimer’s disease that affects the back of the brain, the occipital lobe. It is the type of Alzheimer’s disease with which the author Terry Pratchett was diagnosed.
Terry continued to publish books after his diagnosis until he passed away in 2015 from PCA-related complications.
The symptoms of PCA are very specific. Since this part of the brain is responsible for visual processing, people with PCA have difficulty distinguishing colours and shapes, they struggle to recognise faces and lose the ability to read.
Often the classic symptoms of Alzheimer’s disease, such as memory loss, do not appear until much later on. This means that PCA is often mis-diagnosed or only picked up in the very late stages.
It is likely that PCA is more common than we might think since it is often dismissed as problems with eyesight associated with old age.