Understanding PCA

Posterior cortical atrophy (PCA) is a form of dementia that mainly affects the parts of the brain that process visual and spatial information.

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Common first signs and symptoms include difficulties with seeing what and where things are (for example, when driving or reading). This includes:

• problems with reading

• issues with recognition

• difficulty with coordination

• issues with judging distances

• light sensitivity

The symptoms of PCA usually begin before the age of 65 and and people are often in their mid-50s or early 60s when they first experience symptoms. However, PCA can also affect older people and it can take a long time for people to receive the correct diagnosis.

Causes

Posterior cortical atrophy (PCA) means ‘back of the brain shrinkage’ and it refers to the progressive loss of brain cells, particularly in brain regions that process visual and sensory information, such as the occipital and parietal lobes. The changes in the brain that cause PCA can be caused by different disease processes. In the majority of cases PCA is caused by changes to brain cells similar to those that occur in Alzheimer’s disease.

However, the initial symptoms of PCA are very different from those of Alzheimer’s disease. This is because of the different areas of the brain that are affected. In Alzheimer’s disease, the ‘memory areas’ of the brain are particularly affected, whereas in the early stages of PCA the skills controlled by the rear of the brain (such as vision) are more affected.

People living with PCA often preserve their memory and language abilities in the early stages, but experience a progressive decline in vision and/or literacy skills (including spelling, writing and arithmetic).

There are a small number of underlying conditions, as well as Alzheimer’s disease, that can cause PCA:

These include:

Lewy body dementia (LBD) – people may experience visual hallucinations, and may become stiffer and slower in their movements, in a similar way to people living with Parkinson’s disease.

Corticobasal Syndrome (CBS) – people may have difficulty using one side of their body or experience jerky, awkward or slow movements.

Prion diseases (e.g. Creutzfeldt-Jakob disease (CJD)) – very rare conditions in which people may experience a very rapid decline in their cognition.

Very little is known about why PCA affects some people and not others, nor how many people there are living with PCA. Research is leading to improved understanding and you can learn more about ongoing PCA research here.

Diagnosis

The first signs of PCA are often very subtle and may be difficult for the person experiencing them to describe.

People with PCA usually first experience difficulties with vision. Quite understandably, this leads them to consult an optician. However, the visual problems in PCA are due to changes in the brain rather than the eyes, and so an optician will not usually get to the root of the problem. In PCA the problem is that the affected part of the brain is unable to interpret the information sent to it by the healthy eyes.

Problems with spelling, numeracy and learned motor skills have also been reported as early indicators of PCA.

Even once an appropriate referral has been made to a specialist – usually a neurologist, psychiatrist or neuro-ophthalmologist – it may take some time before the diagnosis is made formally. It can typically take 1 to 3 years from the onset of symptoms. As a result, many people living with PCA feel frustrated by the time of diagnosis.