Posterior cortical atrophy (PCA) is a progressive degenerative condition involving the loss and dysfunction of brain cells particularly at the back (posterior) of the brain. In the vast majority of cases, this loss of brain cells is associated with the same pathological brain changes seen in typical Alzheimer’s disease, namely amyloid plaques and neurofibrillary tangles. In other words, PCA is most usually considered to be an unusual or atypical variant of Alzheimer’s disease; it is sometimes known as Benson’s syndrome.
Despite being caused by the same disease process, the effects of PCA and typical Alzheimer’s disease upon the behaviour, thought processes and skills of individuals with each condition are very different. Typical Alzheimer’s disease is most commonly associated with deterioration in memory, language, perception and a host of other skills and abilities. By contrast, individuals with posterior cortical atrophy tend to have well preserved memory and language but instead show a progressive, dramatic and relatively selective decline in vision and/or literacy skills such as spelling, writing and arithmetic. The reason for this marked distinction between posterior cortical atrophy and typical Alzheimer’s disease is that the distribution of the disease in the brain is different; in typical Alzheimer’s disease, disease-related changes are evident across most brain areas, whereas in posterior cortical atrophy the changes are restricted to or focused upon the rear of the brain and so initially only the skills which those brain areas normally support are affected.