Nicci Gerrard is a journalist and campaigner, who writes bestselling novels with her husband under the name Nicci French. She won the 2016 Orwell prize for her reporting on the care of dementia patients in the UK.

What compelled you to write this book?
I didn’t want to write a memoir about my father [John Gerrard, who died in 2014 after 10 years with dementia], partly because there have been lots of wonderful memoirs about dementia and I saw no reason to add another, and partly because he was a private man and I didn’t want to invade his privacy more than necessary. But I did need to write a book about dementia, having witnessed what he went through, and then launching John’s Campaign with my friend Julia Jones. I found myself thinking more and more about what it’s like to live with dementia, and also what dementia teaches us about our sense of self, how we value people, and what it is to be vulnerable. It profoundly shook up the way that I thought about all of those things.

Tell me about the campaign and what you set out to change.
Before Dad went into hospital, he was doing rather well – it was a gradual, quite gentle decline. Then there was this abrupt rupture in his condition because, during his five weeks in hospital, just when he needed us most, we weren’t allowed in to see him. In retrospect it seemed cruel and unnecessary that carers were not welcomed into hospital alongside their loved ones and it absolutely needed to be changed – and it seemed such a simple thing to change.

But it wasn’t that simple…
I thought it would be the shortest campaign in history: it’s one of these very rare proposals where there’s no downside whatsoever. But the NHS is such a fragmented and bureaucratic thing, so it was about changing the culture in each hospital – there was a lot of trudging around, talking to nurses and making sure they joined the movement on their own terms. But now every acute hospital in England and almost every acute hospital in the UK has, in one way or another, signed up to the campaign.

Do you think we’re getting better as a society at facing up to dementia?
Yes, I do. We’re not good enough yet, but the world has changed so radically from 40 or 50 years ago. For my father’s generation, it’s still quite a stigma. They don’t talk about it, they often try to deny it and hide away from it, and that can make it hugely more painful for them and those around them. But younger generations are talking about it and writing books about it, like Terry Pratchett when he had dementia, and it’s part of the conversation. People do feel very scared of it – and they’re right to: it is very scary – but it becomes more scary when you try not to think about it.

Do people with dementia have something to teach us?
Absolutely. The first thing to say is that when someone has dementia, they’re still the same person, they’re still in the world with us, we should still recognise that they have value. Over and again I’ve seen how people with dementia get treated as stupid or even as objects, but they are not stupid – they have a brain disease, but they’re still able to contribute.

In a larger sense, dementia challenges what it means to be human. In the western world especially, we so value autonomy, agency, youth, vigour, purpose, self-sufficiency, but what happens when we’re no longer young, healthy and autonomous, when we’re at the mercy of other people?

Was this a distressing book to research?
No, almost the opposite. There were times before and after Dad died when I was quite all over the place and it felt like a tragedy. But researching the book and meeting people with dementia and thinking and reading about it, I felt immensely more optimistic by the end. It’s not just a story of despair, it’s a story of love and courage and adventure.

Did you encounter any works, literary or otherwise, that captured what it’s like to have dementia?
The novel Out of Mind, written in the 1980s by a Dutch writer called J Bernlef, is beautiful and sad and quite extraordinary. The play The Father by Florian Zeller is extraordinary too, because it enacts the dismantling process of dementia. Those works are both about dementia, but they also make you question the stability of reality.

Do you fear dementia any less now that you’ve looked at it in detail?
Yes. That doesn’t mean that I think it’s any less harrowing. I just fear it less because I’ve thought about it more. It’s like shining a light into an area I’ve tried not to look at. I have to say that maybe, I hope, I would try to find my own way out – not really out of fear of it, but out of wanting to leave the party before the party leaves me.

You mean you would take your own life before dementia took hold?
Yes. But I hesitate to say that, because actually it would be very difficult. You’d have to do it while you still had the capacity. Maybe, when it came to it, I’d keep on thinking: one more walk up the mountain, one more glass of red wine, one more meal around the table with my family…

Has writing the book helped you deal with your father’s death?
Yes. It was a way of giving myself permission to patiently think through what happened and acknowledge it and to say goodbye. It was like trying to lay a healing hand on it. And that’s what I wanted to do in a bigger sense with this book: to lay a healing hand on an illness that can be so chaotic and disorderly and dreadful.