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Terry Pratchett and his rare Alzheimer's diagnosis

Following the BBC2 docu-drama about Terry Pratchett, read more about posterior cortical atrophy (PCA), the rare form of Alzheimer's disease he had.

In 2007, aged 59, Sir Terry Pratchett publicly announced that he had a rare form of early onset Alzheimer’s, called posterior cortical atrophy.

A docudrama on BBC2 followed the literary career of the beloved author, who was well known for his humorous and thought provoking fantasy novels. 

Here, Alzheimer’s Society Research Communications Officer Tim Shakespeare discusses what we know about posterior cortical atrophy.

Terry Pratchett and dementia

Before I joined Alzheimer’s Society, I carried out research into posterior cortical atrophy - the rare form of Alzheimer’s that Terry Pratchett was diagnosed with.

In this post I describe what it is, how it affects people, and what research is taking place. Just to warn you, the post discusses the end stages of Alzheimer’s disease which some may find upsetting.

Terry Pratchett had a type of dementia that affects vision, not memory


For many people, the first time they heard of posterior cortical atrophy (PCA for short) will have been when Terry Pratchett announced his diagnosis with the condition

Posterior cortical atrophy literally means ‘back of the brain shrinkage’. The back of the brain is where we interpret visual signals from the eyes and posterior cortical atrophy affects the ability of the brain to process these signals.

Symptoms of PCA can include difficulty reading, recognising objects and judging distances. Problems with spelling and calculation are common, as these skills rely on similar areas at the back of the brain.

Memory and language skills are usually less affected in the early stages of the condition, but as the disease spreads to more parts of the brain, people may develop more typical symptoms of Alzheimer’s disease such as memory loss and confusion.

Vision and perception can be affected by other types of dementia too, but in posterior cortical atrophy these are the first and most severe symptoms.

People tend to develop posterior cortical atrophy at a relatively young age, in their mid-50s or early 60s. We don’t have exact numbers but there are about 42,000 people in the UK with a form of dementia that started before the age of 65, and of this group only a small proportion are likely to have posterior cortical atrophy.

Raising questions

From a scientific point of view, there’s an interesting question that could be answered with research into posterior cortical atrophy. People with posterior cortical atrophy have the hallmarks of Alzheimer’s disease in their brain (clumps of toxic proteins called amyloid and tau) but these clumps are found in back of the brain. In Alzheimer’s disease these toxic proteins are found in the memory centres, which is why memory loss is one of the main symptoms associated with this condition.


The reasons behind why Alzheimer’s disease can affect different parts of the brain in different people are not understood. There must be some genetic, lifestyle and/or environmental factors that cause the visual areas to be vulnerable or the memory centres to be protected in some people. Finding out what these are could give us important insights into Alzheimer’s disease.

It’s also important to improve our understanding of the symptoms that people with posterior cortical atrophy experience so that we can support them better.

Some of these symptoms might seem quite unusual, for example some individuals have a disordered sense of balance and they might experience dizziness or lean to one side. Alzheimer’s Society has given research funding to Professor Sebastian Crutch at UCL to investigate these balance problems. We hope the project will improve understanding, detection and management of these more unusual symptoms.

A progressive condition

As with other forms of dementia, there is no cure for posterior cortical atrophy, and how quickly the symptoms progress depends on the individual person.

Treatments that work for Alzheimer’s disease may help relieve symptoms for some people with posterior cortical atrophy, but over time the disease progresses to affect more aspects of thinking and more aspects of everyday life. Terry Pratchett grappled with the issues around the later stages of Alzheimer’s and discussed them in the years following his diagnosis.

The period when someone with dementia is approaching the end of their life is difficult and emotional. People with dementia have the right to dignity and a ‘good death’ and people may wish to discuss these issues in different ways and at different stages. For those who wish to find out more, there is information about end of life care on our website.

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My wife has been diagnosed with PCA yesterday. She is 62 years old and her Geriatrician has recommended her to use Exelon patch(9.6mg). Does this help?

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Hi Alex,
I'm really sorry to hear about your wife's diagnosis.
We have some information on our website which you may find useful. You can read about drug treatments (including Exelon) here:…
If you need any further advice and support, remember you can always call our helpline. Please find the details here:
Hope this is helpful
Alzheimer's Society blog team

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I was first diagnosed with frontal temporal dementia in 2016 at the age of 56. About 6 months ago they decided that although most of my right frontal lobe and parietal lobe have died off I was not exhibiting the symptoms that would have gone along with this diagnosis. In December of 2018 I had another of several MRI'S and during my appt with my neurologist he told me that I had PCA. If anyone has documented the symptoms of someone who has suffered through this horrible disease could you let me know. Not knowing is the worst part.
Thank you, Angela

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Hello Angela, thanks for getting in touch.
I am sorry to learn about your recent diagnosis of PCA.
I hope that I will be able to provide you with some information which may help alleviate the difficulties of not understanding your diagnosis.
Posterior cortical atrophy (PCA) is a form of dementia where damage is focused at the back (posterior) of the brain, the region responsible for visual processing.
In nearly all cases the underlying cause of cell degeneration is amyloid and tau pathology, the same as in Alzheimer's disease. PCA is thus often called an 'atypical Alzheimer's disease'.
Early symptoms of PCA are problems with vision, performing skilled movements and literacy skills. Unlike typical Alzheimer's, someone with PCA will initially have well-preserved memory. Later stages of PCA progress to resemble typical Alzheimer's disease.
PCA tends to affect people in their 50s or early 60s. They are often referred to an optician before seeing a neurologist. PCA is rare (five per cent of all cases of Alzheimer's disease) and is often slow to be diagnosed.
Drug treatment is as for Alzheimer's disease. Practical visual aids such as talking clocks and watches can help, as can talking books and audio recordings available on CD or online.
I have attached a link to a page on our website which includes a signpost to a PCA support group which I hope that you will find helpful.…
I do hope that this has been helpful. Please don’t hesitate to contact our Helpline on 0300 222 1122 if you require any further information, advice or support.
You may also find it helpful to visit our online community 'Talking Point', as other people may have discussed similar issues. You don't have to sign up to search through the forum, so you could just read other peoples' posts and find out about their experiences. The forum can be found at:
Kind regards
Helpline Adviser

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My husband is in nursing home after stay inhospitable with urinary infection. I have just found out that he was diagnosed in 2004 with Dementia 22. he was not allowed home as it takes 3 people to change him.He cannot talk feed himself is doubly incontinent. He cannot stand.Are these later stages of this ?

This is helpful

Hello Elizabeth, thank you for your comment.
I am sorry to hear of the change in your husband’s current condition.
The symptoms that you have highlighted such as an inability to feed himself, incontinence may be synonymous with the later stages of the dementia. However, this is not finite. A medically trained professional would be in a better position to carry out a comprehensive examination and assessment of your husband in order to rule out any other possible causes for these changes, such as further infection.
I have attached a link to factsheet: The Later Stages of Dementia, which looks at the the progression of dementia and symptoms in the later stages.…
Talking Point is an online community run by Alzheimer's Society that provides valuable support, tips and advice to anyone affected by dementia, this includes family friends, carers as well as people with dementia. Some people have found this to be a useful support:
Should you wish to discuss any of the above please do not hesitate to contact National Dementia Helpline. Telephone: 03002221122; Email: [email protected]. Opening times: Monday to Wednesday 9am-9pm; Thursday, Friday 9am-5pm; Saturday, Sunday 10am-4pm.
Kind regards
Helpline Adviser

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My mom, 76, was diagnosed with PCA. Can someone please give me an idea of what to expect? Will she forget who I am, will she need full time care, will she die???

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Julie: I am so sorry about your mother. This is a very challenging diagnosis. My husband died one year ago at age 64 of PCA. I live in the US. I kept notes over the course of his progression (18 months) that you might find helpful in adjusting. It was entirely trial and error (many minor adjustments were a big help), but perhaps my solutions might help you with your mother. I was able to manage very him well at home until his death.

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I have a client who is 64 with PCA. He was diagnosed 6 yrs ago and recently took a huge decline. Any info is helpful. He is having hallucinations now.

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With PCA Valdeana is disabled but we still have Valdeana with us.

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My wife has been struggling with PCA for some years, although she was only diagnosed in 2015 at the age of 60, following a MRI scan showed her Right Parietal Lobe had all but gone. Prior to that her diagnoses was Mild Cognitive Impairment but as she said "there was nothing 'mild' about it for her"! Valdeana had dealt with visual and memory issues since the turn of the millennium, being diagnosed with a Holmes Adie Pupil in 2000, and if I read through the literature I can see minor incidents as far back as the mid 90's. Although we have been plagued by it's consequences for our careers, finances and health, I do feel that it's slow progression has allowed her brain to adapt, considering the total loss of the Right Parietal Lobe and 70% of her left Hippocampus I remain astonished by how she manages with the disabilities Alzheimer's inflicts. Today Valdeana is at daycare, to allow me to work part-time and time to deal with those things I can't deal with when being her carer. Many people who have family at the same Daycare do not, initially realise Valdeana is a suffer. What I would say is that Valdeana is still herself, just with a lot to deal with in her disabilities. She remains my fiery little Red-Head with a mind of her own. And for that, I'll always love her.

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that is so sad and so tender. Thanks for sharing your thoughts. Your redhead sounds like a real cracker!

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On line there is a report by a Dr Mary Newport of Tampa , Florida. To the effect that Altzimers is a kind of diabetes of the brain whereby the brain cannot absorb glucose, but that taking pure Coconut oil enables the brain to digest the glucose via a substance called tryglissarines (may have misspelt that) and that there is a Professor Ceiran Clark at Oxford
University working along the same lines, has anyone heard of this and is there any sort of trial going on,

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Hi Peter, thanks for your comment. We have a page on our website about coconut oil here which will give you some more information about this:…

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My sister has PCA and is now in the latter stages of the disease. The development of her disease was completely different from Alzheimer's. This caused her and us much distress in trying to help her deal with her disease. When she needed full time care, we were unable to find a care home which understood her condition and she and we were frustrated by the lack of awareness. She is now in a dedicated working age dementia home. I only wish we could have found it earlier. I am so glad that there is now funded research into this condition. If we can help in any way, please contact me.

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