Chris Williams doesn't have any photographs of his mother on his phone.
"We don't tend to take pictures with Mum now because when we have in the past, you look back and see something you don't want to remember," the 22-year-old says.
"You see a face with no emotion in it. That's not a memory you want to cherish."
Chris's mum has dementia. She was formally diagnosed at the age of 59, when Chris was 19.
There are 850,000 people in the UK with dementia. Almost two out of three of those have the kind of dementia Chris's mum has - Alzheimer's disease.
Like about 40,000 other people in the UK, she is living with young-onset dementia, meaning she was under the age of 65 when her condition was diagnosed.
The most talked-about symptom of Alzheimer's disease is memory loss. But, especially in younger people, other problems with vision, speech, behaviour or decision-making may emerge first.
"With Alzheimer's, there's a general focus on memory," says Chris, who is training to be a teacher in York.
"It's much more than that, it eats away at who they are as a person until there's nothing left. My mum has been less human since the day she was diagnosed.
"There are photos of her from before, and when I look at them I'm surprised, because I've forgotten that she used to be like that.
"When I see her smiling in a photo, that is a shock to me because I haven't seen in her smiling naturally in such a long time."
Chris came out as gay to his parents when he was 16 and says both his mum and dad were accepting when they found out.
But his mother's loss of memory means that she has forgotten that ever happened.
"She became less understanding. She became forgetful about it," he says.
"These days when she asks, I just say, 'No, I don't have a girlfriend.'
"When I came out she was a different person. These days she's more of a stranger and I don't need to tell a stranger about the details of my life."
Over a drink, Chris explains what it's like when he goes back home to visit and tries to take his mum out for the day.
"She more than likely would say nothing," he explains.
"She would be sat staring at a wall, staring at her drink, looking comatose. She doesn't exhibit emotion. She has to be forced to smile.
"She wouldn't know where she was. She wouldn't know what was happening and even if I asked her about it afterwards, she wouldn't have a clue.
"If she was going to say something, it would be, 'Can we go home?'
"If I make the journey home and after 10 minutes she wants to leave, that can be quite a heartbreaker.
"There's not much to be gained from spending time with her and that's one of the most difficult things."
"If a parent develops dementia, it can fundamentally change the nature of the relationship with the young person," says Kathryn Smith from the Alzheimer's Society.
"Where they may have been able to rely on them for support and advice previously, they [the child] might find they're the ones who need to give the support.
"They have to be more patient and more understanding."
As part of their current campaign to raise awareness, the charity says most people think dementia is just a "natural" part of aging. Instead they want people to talk more openly about the condition, which they say will improve the kinds of treatment people receive.
Like most children, Chris only refers to his mother as "mum". But it's only at the end of the interview that what her life was like before diagnosis comes up.
"When someone has dementia, they almost lose their identity," he says.
"When I'm talking about my mum, I often forget to give her name, forget to give any information about her apart from her symptoms because those represent who she is now to me.
"Her name is Janet Williams. When she was diagnosed, she was a housewife. She raised five children, including me, and she dedicated half her life to that. It was what she did best.
"She worked in a bank before then, but we always saw her as just Mum. Now that she's not really Mum, who is she?"
It's hard when Chris sees his friends post photographs of their families on Facebook, or his university mates go home to be spoiled by their parents, because he says when he goes home, he has to care for his mum instead.
Chris says he feels cheated out of his mum knowing him as an adult and being able to talk to her now.
"I would want to apologise for all the things I said and did when I was 16. I was a typical teenager. I was thinking all about myself. I was a nightmare.
"Just telling her that I loved her and I still love her regardless. I wish things were different."
Frequently Chris describes his emotions and experience as "grief" or "mourning".
"In your darker moments, you look at the situation and think, 'Would it have been easier if one day, she'd been in a car crash and she'd gone and that would have been the end of it?'
"And actually, I think the reality is yes, it would've been.
"It's an awful thing to think that. What I'm effectively saying is in some scenario, I would prefer that she wasn't here."
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