Sir Terry Pratchett and his rare Alzheimer's diagnosis

Read about Sir Terry Pratchett's dementia diagnosis of posterior cortical atrophy (PCA), a rare type of Alzheimer's disease.

In 2007, Sir Terry Pratchett publicly announced that he had a rare form of young-onset Alzheimer’s disease, 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. 

Tim Shakespeare, former Research Communications Officer at Alzheimer’s Society, discusses what is known about posterior cortical atrophy. 

Before he joined the Society, Tim carried out research into this type of atypical Alzheimer’s disease. Here, he describes how PCA affects people and what research is taking place.

Please be aware this post discusses the end stages of Alzheimer’s disease, which some may find upsetting.

Terry Pratchett holding a Dementia Friends sign that reads 'It's possible to live well with dementia and write bestsellers "Like wot I do"!'

Sir Terry Pratchett supported Dementia Friends.

Sir 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 Sir Terry Pratchett announced his diagnosis with the condition. Sir Terry was only 59 at the time.

PCA often starts much earlier than more common types of dementia with diagnosis typically happening in a person’s 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 diagnosed before the age of 65. This is known as young-onset dementia. Only a small proportion of these are likely to have PCA though because it’s a rare type of dementia.

The back of the brain

Posterior cortical atrophy is caused by Alzheimer’s disease starting in an unusual place in the brain – at the back.

This is different from more typical Alzheimer’s disease, which tends to start in the middle of the brain, and so it causes different early symptoms.

The back part of the brain is where we make sense of the information coming from our eyes.

It’s where we work out what objects are around us, how big they are (or how far away), whether they’re moving, and how they all fit together in a three-dimensional landscape. 

An example of how vision is affected

The back part of the brain works out that the white plate pictured below is a separate object from the white table underneath it.

A round white plate on top of a white table with a silver knife and fork either side. Source:

When this part of the brain gets damaged by disease, the first problem is being less able to see things properly.

The person’s eyes may be perfectly healthy but they can’t ‘see’ the plate.

Symptoms of PCA can also include difficulty reading, recognising objects and judging distances

A person with PCA may also have problems reading because the shapes of the letters and words appear jumbled or don’t seem to mean anything.​

Some types of thinking are also affected which aren’t directly visual but still rely on this part of the brain. These include problems with spelling and arithmetic. This is probably because these skills rely on us being able to ‘see’ the way the word is spelled in our inner eye, even if we don’t actually see it in real life.

As the disease progresses, the person will start to develop other symptoms, such as problems with thinking, memory, and language.

Although PCA is rare, the visual problems it causes can also happen with more common types of dementia

Thanks to many wonderful volunteers with PCA who take part in research studies, we have learned a great deal about helping people with dementia who are having problems seeing things clearly.

This includes using better contrast and colours in living spaces and avoiding confusing patterns wherever possible.

Raising questions about posterior cortical atrophy

From a scientific point of view, there’s an interesting question that could be answered with research into posterior cortical atrophy.

People with PCA, like Sir Terry Pratchett, have the hallmarks of Alzheimer’s disease in their brain (clumps of toxic proteins called amyloid and tau) but these clumps are found in the 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.

Illustration of the four lobes of the cerebral cortex. The brain is divided into four parts. The lobe to the front is the frontal lobe. Towards the top of the brain and behind the frontal lobe is the Parietal lobe. At the back of the brain is the occipital lobe, and in front of this and underneath the other two lobes sits the temporal lobe.

The occipital lobes are located at the back of the brain and mostly deal with visual information.

The reasons 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 risk 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.

Dementia research for PCA funded by Alzheimer's Society

Alzheimer’s Society previously funded Professor Sebastian Crutch at University College London to investigate these balance problems. This project found that people living with PCA have a ‘tilted’ representation of their body posture within their brains, which could affect the way they interact with the world around them.   

We are currently funding Dr Keir Yong at University College London, who is investigating how to improve coordination in PCA. Dr Yong’s project aims to understand how dementia affects activities that involve reaching and coordination such as eating and dressing. This aims to inform the development of strategies that promote independence in people with posterior cortical atrophy and Alzheimer’s disease.

Our dementia advisers are here for you.

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.

Sir 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. 

You can also call our Dementia Connect support line on 0333 150 3456 to speak with our advisers, or discuss your experiences of dementia within our online community, Talking Point.

Get your copy of our factsheet

Our free factsheet on Rarer causes of dementia is available to download as a PDF, or you can order a printed copy by post.

Download a digital copy Order a printed copy

This article was first published by Tim Shakespeare in February 2017 and most recently updated by Simon Wheeler and the Research Engagement team in February 2022.


My late wife Jane after losing her job for making mistakes and her inability to get new employment as she had a lack of understanding of things she used to take in her stride; along with things both my family and I thought strange in isolation which when comparing notes after she was diagnosed with Alzheimer's made us all think ah! She progressed rapidly from her early 50s and very quickly became bedridden. My Youngest daughter and I took on her nursing even though it cost my daughter her relationship with her partner. For my part I'd been separated from Jane for 10 years but very amicably, so living nearby and retired on health grounds I was able to do the day shift and my daughter the nights. We were asked if we wanted help but felt 24 hour care from us was the least we could do for a wonderful lady. She eventually lost the power of speech but apart from the usual problems I was very concerned that she had frequent what I called waking fits where she would flail her arms and legs and all I could do was hold her hands and as she stared terrified into my eyes sing her songs until she relaxed and slept. I kept asking the Doctors and nurses why this should happen and how we could stop them but they kept saying it was just part of Alzheimer's. When they became really frequent I had to video her for a while even though it tore me apart. When I showed the Doctors everything changed and immdiately they changed her meds. However, things just didn't seem right as she constantly repeated strange phrases and was really agitated. One occasion she was admitted to hospital with a bad UTI Which we were told is not uncommon even though we were super vigilant about hygiene and the doctor commented on how stiff she was and I agreed and said that when I would hoist her to her day chair she always lay flat with her legs straight out. Nothing more was said except when she was clear of the infection the same Doctor who had consulted with the original hospital that had made her diagnosis advised she stayed for another two weeks and make the forty mile round trip to the other hospital for a rescan on discharge. To cut a long story short instead of making the stressful journey, whilst still within the two weeks the other Hospital sent a team to Jane's hospital and did the scan there. That's when they discovered they'd originally misdiagnosed her and in fact had PCA. (a few weeks later at home we received a notice of Jane being sectioned for those two weeks so it became clear the doctor who hadn't told us about the order had pulled a flanker and forced the visit of the original team to his hospital. I would love to thank him) From that point on meds were changed and she became much more peaceful and despite what many visiting medics thought she obviously knew who we were as she started communicating with her eyebrows and puffing noises if she was, thirsty, hungry or just plain annoyed with my constant chatter. She showed her wicked sense of humour almost up to the end. Just one of many examples, my daughter treated her as her baby but when she actually kissed her and said to me "shes my baby" Jane's eyes went wide and somehow overcame inability to move her arms more than an inch or two plus her complete inability to speak and gently punched my daughter's chest and said crossly " baby" After a shocked silence my daughter and I just laughed and laughed. After raising her eyebrows Jane just puffed, closed her eyes and smiled. Almost to the end now and then she would just say one word, my daughter's name. When lockdown started the many visitors Jane received zeroed.. When I first started video meeting her I explained about the lockdown but she kept turning her head away from the phone my daughter held and made it very clear she didnt believe me. So I began sneaking down and visiting by standing in the garden after delivering groceries and my wife would sit in her day chair inside the open door. But her condition went downhill quickly and when we were able to bubble she had lost a lot of her awareness. Eventually she was put on a pump and we nursed until her 66th birthday when she legally retired and which she had planned for years to regularly go to London to musicals and tea with friends at Harrods. We gave her a party with close friends and though dysphagic for a couple of years plus we were told not to feed her or give her drinks. We put a token piece of cake in her mouth which she sucked for ages and wet her mouth with her favourite Archer's and lemonade then all held a bit of her arms and hands and sang Happy Birthday which I like to think she enjoyed. Then three days later halfway on my fifteen minute walk down to see her I received the call from my daughter to say she had passed. That was 11th October 2020. We all miss her terribly and I actually live in Jane's and my house now due to the economy downturn along with my daughter who late in life is expecting her first baby and I live in the room Jane lived and died in, struggling and failing hopelessly to provide her the support her Mum should be here to give.

My partner Wendy was diagnosed with PCA 5 years ago, aged 57. At first she changed quite slowly until early last year
when things changed rapidly. Wendy is a
loving, gentle soul and yet this horrible disease made her violent. The consultant arrived for a 6 monthly check
Wendy became aggressive with us all
2 days later she was sectioned and taken to a hospital. This was a real shock as I had no warning it was going to happen. After 3 months sorting her medication she was moved to an amazing nursing home. Wendy is now happy in her own world although she can't really see anymore which I think makes PCA. the worst form of Alzheimers. It's a long journey and you have to look after yourself as well, good luck to you all.

Our daughter who is only 28 has recently been diagnosed with PCA my wife and I and our daughter are devastated by this news and we have been told by our team that they have never witnessed this condition in some one so young - we are reaching out for support and advice that may help us deal with this enormity in our lives with some one so young and with so much still to do in her short life - we are all at a loss at to why and are feeling completely helpless any one who has any knowledge of this horrible disease in some one so young would be greatly appreciated

Hello Andrew,

We're very sorry to hear about your daughter's PCA diagnosis.

Please know that we're here for you. We'd strongly recommend talking to one of our dementia advisers who can learn more about your situation and give information, advice and support. You can call our Dementia Connect support line on 0333 150 3456:

We also have some information on our website about young-onset dementia and PCA that you may find helpful:……

You may also find it helps to talk to other people with similar experiences. Our online community, Talking Point, is a place where you can connect with others online, ask questions and share experiences:

We hope this is all useful, Andrew. Please do call our support line for more detailed advice and support relevant to your daughter's situation.

All the best,

Alzheimer's Society web team

my wife was diagnosed with PCA in Oct 2020, she's had a rapid decline since then (12 months) , and especially in the past 6 weeks. We are in the stage now with loss of appetite, "night terrors", delusions, and hallucinations. She has just been prescribed anti-depressant/anxiety tablets. Hand tremors now as well. This disease is horrible and scary. Please read our story

You are spot on with the timescale. My wife was diagnosed with PCA at 52, having had some of the symptoms you describe, but virtually all of the rest are now familiar to me.
You are right about reaching out. Friends walk out with her 3 times a week. . . it's a lifesaver for both her. . she's happy being out and about; also for me, as I have space to breath and do some of the necessarys.
Small things count, like we did this morning when we found a doctor in our new medical centre who was sympathetic to our situation. . . he is a person of the same age, 58.
I try not to look too far in the future, but am also mindful of the things that might be needed.
I have found that many 'dementia organisations' have their own agenda rather than helping they to advise you as to how to manage your rather big load (breathing exercises training - I've been breathing for 63 years and have got rather good at it!), rather than offering to carry part of that rather big load.
Best wishes

I read your blog, and I wish I had found it a year and a half ago, so I could brace myself for what was to come. My mother was diagnosed a year and a half ago (age 60) with PCA and everything you all have lived with is exactly what my mother lived with for a year and a half. Nobody told me what her life would be like, and I believe it’s because so few people have been diagnosed with PCA. About two months a ago, when I thought I was at the end of my rope, I took her to the bathroom and she passed out. She was taken by ambulance to the ER. The doctors said they couldn’t believe that we were able to care for her and that we had done all we could do. They said it was time for professionals to take over. Unfortunately, she declined very quickly in the ER. The day before she had just walked two miles and was in decent spirits considering her condition. She was moved into hospice where she passed peacefully a week later surrounded by my brothers and father. Her time in hospice was the most peaceful and relaxed we had seen her body in a year. They said they had only seen two people with her disease and how quickly she declined was what they had experienced with the other two. This is just from my experience being my mother’s caretaker. I think the fight and the energy it takes the person living with PCA is astronomical. Every minute it seemed like my mom was fighting something (hallucinations, tremors, memory, speaking, UTIs, fear, confusion, vision). My mom told me everyday it was something new and scary. I really believe she was so exhausted she was able to tell herself, “no more.” And that’s why she was walking and talking one minute and a week later passing away. I know you all are exhausted. I’m thinking of you and every person and family living with this terrible syndrome that strips away ever ounce of a persons dignity. Watching her pass was beautiful, knowing she would never be fearful again. My entire family has been relieved. I cannot tell anyone how much we hurt and miss her, but the last year of her life was like living in a nightmare that had no end. She only lived with the disease for a year and a half and that was more than enough.

My father in law has been diagnosed recently with PCA ,but deterioration is massive, from week to week is getting worse. I work in care system and look after many people how have mental illnesses dementia alzheimer's, but have not seen anything like that.its scary and we all feel helpless.

Hi Ella,

We're really sorry to hear about your father in law, it sounds like you and your family are having a very difficult time.

We would strongly recommend speaking with one of our dementia advisers, by calling the Dementia Connect support line on 0333 150 3456. They will be able to listen to you, and provide advice and support specific to your family's situation. (More information about the support line, including opening times, can be found here:

You might also benefit from connecting with other people affected by dementia within our online community, Talking Point. Here, carers and other people affected by dementia share stories, advice, and offer support to others who may be going through similar situations. You can have a browse of other people's experiences, or sign up for free here:…

We hope this helps, Ella.

Alzheimer's Society blog team

Hi Ella,

My family member has just been diagnosed too and we are experiencing the same. Heavy week to week deterioration. I find it hard to connect his diagnosis and symptoms with other as his seems to be extreme.

my wife has pca, progressing rapidly... please read our story
hang in there

I was diagnosed with it the same time as Sir Terry Pratchett. I had all the scans and was diagnosed with Alzheimers. The most frustrating thing I find is that none of the specialists were able to tell me what to expect as they said everyone is different. I asked if anything would help and they said not really. However I started doing daily quizzes and stopped watching soaps and changed to anything informative. History, Discovery, Biographical, Detective series etc that gave you chance to think and try and work out who did it before they told you.
I am not saying that my symptoms slowed down or stopped but I do feel trying has definitely helped me. I read a lot and embraced social media to some extent.

One thing I was totally opposed to was joining clubs or going to sessions with others also afflicted. I suffer with mental health problems like depression and frustration but have to try and control it. I have tried mental health services but I have to say that their involvement was minimal, 2 visits and they stopped coming. When at my lowest I was told try not to think of the negatives and concentrate on your achievement raising a family etc and that was it, one session and a follow up phone call and then they signed me off. My children are all grown up and have their own lives to lead so interaction is probably minimal except for one daughter who I see almost every day. I live with my son but he has his own problems and we can clash. I am hyper critical to the extreme and his sometimes expects me to do more but physically I am unable.
I think spending most of my time in my room with my dog allows us to rub along. I have other major illnesses and think how easy it would be to give in but my psyche is to say Fxxx It, it will not win. It will not belittle me and when I do go I will have fought it every step of the way.

I do think though that it is a shame that more time couldnt be given to support us, even if it was just to allow us to talk and get things of our chest. My advice to others is decide what you are going to do about it. It is to fight it do it with resolve and fight every step of the way

I know it will get me but until then ve day to day. Start every day as if it is your first. Appreciate the little things

Hi my husband was diagnosed very early on with PCA, about 8yrs ago. I changed his diet and life style. Whether this slowed it down not sure. However, he struggles with word search and stammers. His emotion can be extreme to me, when he crys he sobs , its heart breaking and when he laughs way over the top. He has no filter when saying things. If he's thinking something he just says what he's thinking and some are very inappropriate. Wondering what stage of his illness he is at.

My husband is 67 and was diagnosed with PCA 4 years ago. My heart is breaking snd I’m scared too death. The comments on this page really help me. Thank you

With my pca i only have breakfast each day,, have done for months,, just dont feel like eating,, dont lose weight,, drinking ok,, but if i force myself to eat i get stomache pains. I feel full all the time. I do get pains at the back of my head,,, its just a terrible thing.

My Husband Bryan has PCA he's had it for 6 years and is 58 .Everything is upside down and back to front , he can't dress himself and a lot of other things but he has just started flinching .He does it when he's awake and asleep quite a lot .It started a couple of weeks ago .

Hello Sally,

Thanks for getting in touch. We're really sorry to hear about the recent changes you've noticed in your husband's symptoms. It sounds like you're going through an especially tough time.

Please know you can speak with one of expert advisers on 0333 150 3456. They will listen to the situation and provide information, support and advice:

We hope this is helpful, Sally.

Alzheimer's Society blog team

Hi my husband is 52 now and was diagnosed at 50 with early onset after several years of being told he has clinical depression, after reading about night blindness I think he has PCA. The reason I’m interested in your post is that he is flinching and has been doing this for some time I have asked about this often and been dismissed, with thing like he’s dreaming, while he eating? Have you any idea what the flinching means?

Hello Lorraine, thanks for getting in touch.

Our online community is the ideal place to talk to others going through a similar situation. If that appeals to you, take a look at Talking Point, where you can share your experiences and ask questions of the community, or just read what other people affected by dementia have to say:

You may also benefit from speaking with one of our dementia advisers on 0333 150 3456 if you have questions about different symptoms of dementia:

We hope this is helpful, Lorraine.

Alzheimer's Society blog team

My wife was diagnosed with PCA 3 years ago but had been experiencing difficulties and symptoms 3 years before that. She has been twitching/flinching as well for the past 9 -10 months and it is now getting worse and more pronounced. We have been in our home for 22 years and she finds problems now finding her way around and also has problems dressing/undressing.

My husband has PCA and has tic like movements especially in his left arm which is his affected side. Seizure meds reduced the major jumping of his arm. He still has fine tics in his fingers.

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?

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

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

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

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 ?

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

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???

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.

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.

My husband was just diagnosed with PCA about 3 weeks ago. He had cancer 2 years ago and we thought he had chemo brain, so this was a shock. Can you please tell me what to expect as we progress through this?

Hi Kathy,

We're really sorry to hear about your husband's recent diagnosis. This must be such an emotional time for you. Please know that support is available and we are here for you both.

You may find it helpful to talk to one of our Dementia Advisers for information, advice and support. You can call our Dementia Connect support line on 0333 150 3456. Find more information about the support line, including opening times, here:

You might like to talk with other people affected by dementia within our online community, Talking Point. Feel free to browse and read others' experiences, or you can create an account to reply and connect with others who may be going through a similar situation:

In the meantime, you can browse through a number of pages on our website related to PCA, including real stories and experiences:…

I hope this is helpful, Kathy. Please do call the support line if you need us.

Alzheimer's Society blog team

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