1. What is posterior cortical atrophy?
2. Differences to typical Alzheimer's disease
4. Getting a diagnosis
6. Later stages of the disease
8. Supporting people with posterior cortical atrophy
9. Download this information
What is posterior cortical atrophy?
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, posterior cortical atrophy is most usually considered to be an unusual or atypical variant of Alzheimer’s disease.
Differences to typical Alzheimer’s disease
Despite being caused by the same disease process, the effects of posterior cortical atrophy 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.
The most common problem first noticed by individuals with posterior cortical atrophy 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 (for example household items in a catalogue, especially if the pictures were taken from obscure angles or the picture is incomplete)
- recognising faces (for example TV characters, friends, relatives)
- appreciating the spatial location of objects around them (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 (for example when driving, when 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 (for example 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 control.
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).
Posterior cortical atrophy 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.
Getting a diagnosis
Posterior cortical atrophy 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, as mentioned earlier, 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.
The underlying cause of posterior cortical atrophy in the majority of cases is abnormal alterations to brain cells similar to what is seen under the microscope in Alzheimer’s disease. However, a small number of other conditions can 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.
There is no diagnostic test for posterior cortical atrophy. However, tests such as specialised visual tests (organised by eye-specialists), neuropsychological tests of cognitive skills (for example 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. It may be difficult to come up with one diagnosis in life and a definitive diagnosis can only be made once the brain tissue is examined by the pathologist. Posterior cortical atrophy is a rare condition but its exact prevalence in the normal population is currently unknown.
Later stages of the disease
As the disease progresses, word finding, day-to-day memory and general cognitive functions may become affected. In the later stages of the disease, people with posterior cortical atrophy may develop jerking movements of their limbs and occasionally seizures. Unfortunately as with typical Alzheimer’s disease, the condition is progressive with a gradual deterioration of skills and abilities over the years following diagnosis. The duration of the posterior cortical atrophy condition is poorly understood, with some people living approximately the same length of time as individuals with typical Alzheimer’s disease (on average 10-12 years following the onset of symptoms) and others living with the condition for longer.
Although there is no medication available to treat posterior cortical atrophy specifically, patients may find some of the medications available to treat patients with typical Alzheimer’s disease helpful. The medications are called acetyl cholinesterase inhibitors and include donepezil (Aricept), rivastigmine (Exelon) and galantamine (Reminyl). However, these medications are only designed to treat the symptoms of the disease and are not a cure (see Factsheet 407, Drug treatments for Alzheimer’s disease).
Although individuals with posterior cortical atrophy often show relatively preserved insight, they are frequently very disabled by the decline in their ability to interact successfully with the visual world around them. In particular, the cognitive problems associated with the condition often lead to a loss of independence, cause activities of daily living to be compromised, and inhibit the enjoyment of previous hobbies, especially reading. Such problems can lead to depression, irritability, frustration and a loss of self-confidence. Individuals with posterior cortical atrophy who are experiencing low mood may benefit from a trial of antidepressant medication.
Supporting people with posterior cortical atrophy
There are a number of similarities between the support that may be offered to individuals with posterior cortical atrophy and people with other forms of dementia, especially typical Alzheimer’s disease. These include the distribution of information about available financial benefits (e.g. Disability Living Allowance) and financial provisions (e.g. Lasting Power of Attorney).
There is a range of practical visual aids designed to assist individuals with different types of visual impairment which may be of use to people with posterior cortical atrophy. These include devices such as talking clocks and watches, mobile telephones with simplified displays or pre-programmable direct-dial buttons, and cooking aids such as sensors which beep when a cup is nearly full.
There is also an increasingly wide range of talking books and audio recordings available either on CD or downloadable from the internet, with a range of titles from romantic novels to biographies and technical manuals. Audio guides are also available for many cultural events including the theatre and museums.
Your local Alzheimer’s Society branch will always be willing to talk to you and offer advice and information to support your needs.
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