Posterior Cortical Atrophy
"Posterior cortical atrophy (PCA), also called Benson's syndrome, is the visual variant of Alzheimer’s disease. The disease causes shrinkage (atrophy) of the back part of the brain, causing a progressive decline in vision. People with PCA may often go to see an eye doctor first, thinking that their difficulties are due to a problem with their eyes and that they may need new glasses. Visual impairment commonly develops as people get older, and in most cases a decline in vision is due to this natural aging process. In people with PCA, the visual problems are not due to problems with their eyes. Rather, the shrinking brain can no longer interpret and process the information received from the person's healthy eyes.
In the vast majority of PCA cases, the underlying cause is Alzheimer's disease, and the brain tissue at autopsy shows an abnormal accumulation of the proteins amyloid and tau that form plaques and tangles as is seen in Alzheimer's. Although PCA is almost always caused by Alzheimer's disease, it can also be due to other diseases including Dementia with Lewy bodies and Creutzfeldt-Jacob disease. PCA is thought to affect less than 5% of people with Alzheimer's disease, although epidemiological studies are lacking and PCA has been under-recognized in the past."
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