Christine Lyall-Grant is 65 and has early on-set dementia.
For 22 years, she worked as a literary editor at the Cambridge University Press but had to stop working when she started making mistakes and was diagnosed with Alzheimer's.
She now relies on Post-it notes and other people for her memory.
Her daughter Fiona describes how the illness has affected their lives.
When my mum was first diagnosed with Alzheimer's disease I couldn't believe it.
All our lives were to change within 30 minutes of walking through the neurologists' door
For a start no one in my family had ever been diagnosed with the disease and because she was too young.
I was 34 at the time with a ten-year-old daughter and this is not the way I expected her life (or mine) to end up.
She worked full time, drove a car, babysat for me and did all the usual things anyone who has a good relationship with their mother does.
All our lives were to change within 30 minutes of walking through the neurologists' door.
Five years on my mum still lives alone, is perfectly articulate and generally enjoys life
My mother was initially relieved with the diagnosis, which may seem a strange reaction, but she already knew something was wrong.
Whilst she desperately needed confirmation that the way she was feeling was not psychological, those around her and particularly me really thought her occasional memory loss was nothing more than being stressed or over tired.
Luckily for us, and I say us because her disease affects me too, she was prescribed Aricept at diagnosis.
Because the drug was relatively new at the time - so new she had to have it sent through the post rather than via prescription - no one knew exactly what the long term benefits of taking the drug would be.
Christine could not remember where her daughter lived
However, five years on my mum still lives alone, is perfectly articulate and generally enjoys life.
Her memory however, is of course getting worse.
Very recently she telephoned me to ask me where I live. I thought she was joking - we live in the same street and have done for ten years.
With hindsight I rather unkindly laughed and said 'what do you mean, you know perfectly well where I live'.
The realisation that she was being serious came as a total shock and I ended up standing outside my house on the street waving at her so she would know which front door was mine.
Her future is determined by how quickly her disease progresses
She came down again later that day without any help and much to my relief she had completely forgotten the earlier incident.
Friends and family have generally been very understanding and still keep in touch.
However, one or two have disappeared from her life, obviously finding her disease and personality changes difficult to deal with.
Initially this made me angry and sad; angry that I wouldn't get the support from people I knew and sad for her that long term friendships wouldn't continue.
I would like to end on a positive note, but with Alzheimer's there doesn't seem to be one.
Her future is determined by how quickly her disease progresses.
At some point she will need carers at home to help her wash and dress.
For her the most important aspect of her life is remaining as independent as possible.
As for me, well I will have to help arrange the care she desperately doesn't want and ultimately it will be me along with health care professionals who take the decision to put her into a care home.
It will be me who has to sell her house to pay for her care, me who ultimately takes away her independence and me who has to live with the guilt.
ONE life: My Life On A Post-It Note will be broadcast on BBC One on Tuesday 9 May at 2235BST.