Home     About     Early stages     Living with     Later stages     Fundraising


What causes PCA?

The underlying cause of PCA in the majority of cases is abnormal alterations to brain cells similar to what is seen under the microscope in Alzheimer’s disease. Despite being caused by the same disease process however, 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 in the earlier stages 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.

A small number of other underlying conditions can also cause PCA and result in similar symptoms, at least initially. These include:

Dementia with Lewy bodies, where individuals may also experience visual hallucinations and may become stiff and slow down in their movements, in a similar manner to people with Parkinson’s disease.

Corticobasal degeneration, where individuals may have difficulty using one side of their body Sometimes they have difficulty controlling the movement of one arm, which seems to move on its own as if it had a 'mind of its own'

Prion diseases such as Creutzfeldt-Jakob disease, very rare conditions in which individuals may rapidly decline in their cognition and develop other problems such as jerking movements of their limbs (myoclonus), stiffness, loss of balance control and develop seizures.

Getting a diagnosis

Posterior cortical atrophy (PCA) tends to affect people at an earlier age than typical Alzheimer’s disease, with individuals often being in their mid-fifties or early sixties at the time of their first symptoms. However, it can also affect older people. The first signs are often subtle symptoms which may be difficult for the person experiencing them to explain. Individuals with early visual complaints are typically referred to opticians and eye specialists before referral to a neurologist. However other selective problems with spelling, numeracy and learned motor skills have also been reported. Even once an appropriate referral has been made, it may take some time before the diagnosis is made formally. Understandably, patients may feel frustrated by the time of diagnosis, typically one to three years from the onset of symptoms.


There is no diagnostic test for PCA. However, tests such as specialised visual tests (organised by eye-specialists), neuropsychological tests of cognitive skills (e.g. memory, perception, literacy), blood tests, brain scans (magnetic resonance imagery (MRI) or computerised tomography (CT)), lumbar puncture (examination of the fluid circulating around the brain and spinal cord) and EEG (recording of the electrical activities of the brain) may help to exclude potentially treatable causes such as infection, inflammation or brain tumours. The shrinkage of the back part of the brain as a result of brain cell loss may be visible on the brain scan.

Early symptoms

The most common problem first noticed by individuals with posterior cortical atrophy (PCA) is with vision. Quite understandably, this leads many people to consult their optician, but in fact the visual problems experienced are not related to the eye. Rather, the problems stem from the difficulty the affected brain has with interpreting the information sent to it by the healthy eyes. The precise nature of the visual problems experienced may vary widely but often include difficulty with some or all of the following:

  • recognising objects in pictures (e.g. images in news articles/magazines, especially if the pictures were taken from obscure angles or the picture is incomplete)
  • recognising faces (e.g. TV characters, friends, relatives)
  • appreciating the spatial location of objects (for example missing when reaching out to pick something up, finding it hard to press the correct numbers on a telephone, not seeing something you are looking for when it is right in front of you)
  • judging distances (e.g. when driving, descending stairs).
  • judging the speed of moving traffic
  • perceiving movement among things which are stationary
  • following the text when trying to read a book or newspaper, causing one to miss some lines of text or to read others twice
  • reading particular words, finding that letters appear to move around or become superimposed over one another
  • reading certain types of text (e.g. large print such as newspaper headlines, handwritten notes)
  • experiencing objects as having an unusual colour
  • experiencing increased sensitivity to bright light or shiny surfaces
  • seeing clearly, experiencing double vision
  • seeing clearly, feeling that one eyes are jerking around or not completely under one’s

However, vision is not the primary or only area of difficulty for everyone with posterior cortical atrophy. Skills such as literacy, numeracy, and the ability to make skilled movements may also be affected. Such difficulties may be experienced in the following ways:

  • problems recalling the exact spelling of words
  • difficulties with handwriting
  • difficulties with remembering the shape or name of particular letters or numbers
  • slowness and difficulty with mental arithmetic
  • problems dealing with money and small change
  • awkwardness making gestures (e.g. waving, thumbs up)
  • difficulties with using particular tools, kitchenware or implements (e.g. cutlery, scissors, glasses)
  • problems with dressing and clothing (partly related to difficulties with visual perception).

PCA can affect people in different ways initially. In some instances, the disease affects both sides of the brain equally, leading to a combination of many of the symptoms described above. For other people, the disease affects one particular brain area earlier or more significantly; as a result, problems with spelling and writing for example might be the first sign of the condition with vision relatively unaffected, whereas as for others, difficulties in seeing where objects are might be the initial symptom.

This combination of unusual or atypical symptoms and the difficulties many people experience in getting a diagnosis can often cause people to experience increased levels of anxiety.

There are articles that have been published in the Alzheimer’s Society Living with Dementia magazine that relate to PCA. One, entitled “Dementia and Sight Loss”, includes accounts of personal experience of someone with PCA and sources of advice. It is on pages 16-17 of the August 2010 edition. Another, an article about caring for someone with PCA, can be found in the December 2010 edition (pages 12-13).

What to expect - The Stages of PCA document

The experience of PCA differs from one person to the next, but this document attempts to describe how abilities change during the course of the condition. This document reflects the different symptoms, deficits and challenges faced by individuals diagnosed with PCA relative to more typical, memory-led presentations of Alzheimer’s disease. It was developed with people with PCA and their carers and is based on the well-established ‘7 Stages of Alzheimer’s Disease’ framework.

You can access the full Stages of PCA document here, but we recognise that information about middle or later stages of this disease may be a sensitive topic and difficult to embrace. Below we have included information about stages 1-3, and information about the middle and later stages is available within the corresponding tabs above (or in the full document in downloadable PDF format), should you wish to access it.

Stage 1: No impairment (normal function)

The person does not experience any visual problems, memory or other cognitive problems. An interview with a medical professional does not show any evidence of symptoms of vision loss or dementia.

Stage 2: Very mild cognitive decline (may include problems only recognized in hindsight)

The person experiences subtle difficulties with some complex visual tasks e.g.

-           a loss of confidence in their driving ability owing to finding it harder to judge distances

-           problems using a computer such as being slower to type or enter information

-           difficulties with reading, writing, spelling and/or arithmetic

-           difficulty recalling and writing down telephone numbers

-           difficulty assembling novel devices/objects

The person may experience vertigo or other balance problems (although some aspects of these may develop later or not at all), they may experience difficulties finding the right words when speaking or odd visual sensations (e.g. occasional changes or washes of colour in the centre or periphery of their vision).

These problems may be intermittent, difficult to describe and not noticed by friends, family or co-workers. Insight into, but uncertainty as to the cause of these experiences may contribute to anxiety in some individuals. This stage may reflect the earliest signs of PCA, especially where eye tests reveal no indication of ophthalmological problems.

Stage 3: Mild cognitive decline (Early-stage Alzheimer's can be diagnosed in some, but not all, individuals with these symptoms)

Visual difficulties are acknowledged both by the person in question and their friends, family and co-workers, and the person is likely to decide to stop driving (although some people may have already stopped by this stage). Healthcare professionals familiar with young onset and atypical dementias may recognize a fundamental difficulty in perceiving what and where things are leading to characteristic problems including:

-           Difficulty seeing things which are ‘right under your nose’ or only seeing part of something (e.g. not noticing food on the edge of a plate)

-           General ‘clumsiness’ (in people who were not previously clumsy), such as knocking things over (inaccurate reaching out), putting a glass down sideways, etc.

-           Difficulty finding things in a handbag, cupboard, etc.

-           Difficulties dressing and performing other activities (e.g. DIY, cutting a piece of toast in half) that require spatial judgement (e.g. using stairs) and (e.g. left-right) coordination

-           Inability to tell the time from a clock or watch (especially analogue)

-           Getting ‘lost’ on the page when reading

-           Problems with writing, spelling and dealing with numbers

-           Paying for items with a note or letting vendors select coins for them (to avoid having to handle change)

-           Mild memory problems for recent events, though less pronounced than visual problems – these could occur for different reasons, e.g. able to remember many events very well but difficulty for example learning new tasks

-           Mild difficulty retrieving the correct word in conversation

These difficulties may be accompanied by anxiety; this may partly reflect awareness of the difficulties, but equally anxiety and feeling flustered can exacerbate the visual and other problems. People at this stage may also experience subtle sensory changes and disturbances (e.g. feeling cold).


Financial and legal affairs

We encourage our members to think about organising financial and legal affairs as soon as possible to allow peace of mind that all issues can be dealt with in the way you have chosen, particularly as people with posterior cortical atrophy (PCA) often have difficulties with their signature which can cause difficulties when dealing with legal and financial matters. Specifically, you may wish to consider arranging Lasting Power of Attorney (LPA).

LPA is a legal document which gives the person/persons you have chosen the right to make decisions for you on financial and/or health care matters in case you lose the capacity to make decisions yourself. You may choose to have only one or both LPAs.

The LPA gives the person a choice of conferring broad or limited powers to the attorney to make decisions on their behalf, and a choice of who to appoint. For example, it is possible to appoint relatives to make welfare decisions, but a professional adviser for decisions relating to their property and affairs.

A property and affairs LPA gives the attorney(s) the power to make decisions about financial and property matters, such as selling a house or managing a bank account.

A personal welfare LPA gives the attorney(s) the power to make decisions about health and personal welfare, such as day-to-day care, medical treatment or where the person should live.

A personal welfare LPA only ever takes effect when the donor lacks capacity to make decisions. A property and affairs LPA can take effect as soon as it is registered, even while the donor still has capacity, unless the donor specifies otherwise. The donor can, of course, specify that the attorney may only start managing their financial affairs after they lose capacity, some time in the future.

Further information on LPAs is available from the Office of the Public Guardian:

Office of the Public Guardian

PO Box 16185


B2 2WH

For Customer services phone: 0300 456 0300



For information on the benefits you might be entitled to, please see these pages:


Unfortunately, most people with PCA will have difficulties with driving very early on due to their visual difficulties. If you have been diagnosed with PCA you have a legal responsibility to inform the Driver and Vehicle Licensing Agency (DVLA) of the diagnosis. The driving insurance company should also be informed.

The Medical Advisory Branch of the DVLA decides whether you can continue to drive using the information provided by you and your GP or hospital consultant. Sometimes it may be necessary to take a free driving test conducted by the Driving Standards Agency.

If you are not able to drive there are other ways of getting around. Many people have found practical solutions such as allowing family and friends to help or arranging an account with a local taxi company.

Contact details for the DVLA are as follows:

Drivers Medical Unit, D6, DVLA, Longview Road, Swansea, SA99 1TU.

Tel. 0300 790 6806.



More information about driving and dementia from the Alzheimer's Society can be found here

Telling people

Knowing when and how to tell family, friends and colleagues about a diagnosis of PCA can be difficult - especially as most people given a diagnosis take some to time themselves to come to terms with having a condition they had never heard of before. There is no right or wrong time to tell those around you of course, and you will know best when feels right to you. Talking this through with other members of our support groups who have been in a similar situation can be helpful and we can also provide information about what PCA is on request, in case that’s helpful when explaining it to others.