The truth about dementia is that it affects us all

“When she started the early signs I just thought that she was getting a cantankerous old woman,” says Angela Rippon of her mother in her brilliant BBC documentary, The Truth About Dementia.

“It’s not until you’ve looked after someone with dementia that you really understand what it’s like.”

Two of my grandparents have developed the disease: my father’s father (who was diagnosed with Alzheimer’s, the most common form, and died shortly after) and my mother’s mother (who is currently living with dementia in her late 80s).

I was too young to comprehend what was happening to my grandfather, but my grandmother’s struggle has opened my eyes – not just to what dementia does to the person with the disease, but its impact on the people caring for them.

“You learn to be very very patient and understanding” says Rippon, “and in your quiet moments you mourn as the person you know is dying in front of you.”

The grief I felt in the moment I realised my grandmother couldn’t remember me left me almost inconsolable. And as I watched my uncle, her carer, answer repeated question after repeated question while simultaneously sorting out medication and organising a showering rota for her with my godmother, I quite simply could not understand how he was able to cope.

Fifteen minutes later my grandmother had us up dancing in the living room, singing songs and chiding my aunt’s husband about his waltzing skills. I now take a camera every time I visit, capturing those same sing-a-longs and dance sessions for fear they’ll suddenly cease.

At 87, Mary-Kate is happy to pose for a selfie, even if she does describe herself as "an ould witch"

In the UK there are 850,000 people diagnosed with dementia in its various forms and Rippon says that it’s thought many people over 55 fear developing the disease more than they fear cancer.

In my experience, that’s very true. My mother has accumulated and completed an endless array of brain training books and crossword puzzles since my grandmother's diagnosis, in the hope that they'll keep her mind active and her brain healthy.

“If it ever happens, just put me down,” an ex-boyfriend told me not long after we learned of my grandmother’s illness.

The fear of losing our minds, our cognitive abilities, and the memories of the ones we love is equally, if not more terrifying, than the thought of potentially losing our lives.

You can now even take a test to determine how likely you are to develop the disease, a test many don’t even realise exists because it’s not available on the NHS.

And some, like the documentary’s Sophie Leggett – who may carry a faulty gene that means she will develop early-onset dementia at potentially as young as 37 – can find out if they’ll develop the disease long before it hits.

Sophie doesn’t want to know if she carries the gene, though, because the thoughts of passing her mother’s disease to her daughter are too hard to bear.

Sophie Leggett is taking part in a clinical trial in the hopes of finding a treatment for the disease

Chris Graham faces the same fear for his 10-month-old son, Dexter. At 39, the ex-British Army man is battling the disease that claimed his dad, aunt and brother. His son has a 50/50 chance of carrying the faulty gene, but he’ll have to decide for himself at 18 whether he wishes to take the test for it or not.

Those tough decisions are usually ones we’d associate with diseases like cancer: nobody thinks of dementia as a disease a 10-month-old baby or a twenty-something should have to worry about. But the truth is dementia’s reach is far more widespread.

Be it through the loss of a loved one to the disease, the struggle to care for them, or merely the crippling fear of developing it ourselves, dementia affects us all.

In some ways, it’s been a blessing for my grandmother. She seems to have forgotten she ever suffered with depression, she didn’t have to endure the grief of losing her husband to a debilitating illness that finally claimed him earlier this year, and she remains blissfully unaware of the squabbles that divide her beloved children.

"If she knew, it’d kill her”, my grandfather said before he died.

In other ways, though, the disease is the curse we all believe it to be. My uncle, who cared for her at home for almost four years, struggles to leave the nursing home when my grandmother takes a bad turn. She sobs uncontrollably because she can’t remember where she is or who the people around her are and the laughing fits and dance sessions she demands, or brilliantly brutal one-liners she comes out with just minutes later, offer little consolation.

“It’s just like having a child, but they don’t grow up” says 85-year-old Ida, who cares for her husband, Bob. “Some things break my heart, when I think of the man he was. But I’m lucky, I’ve got so many good friends and the neighbours.”

But it is, as Rippon so rightly explains, so hard for Ida, for those friends and neighbours, for children and grandchildren and, perhaps most importantly, carers, who watch “the person that they love and they’ve known for a lifetime gradually slip away.”

The Truth About Dementia airs on BBC1 tonight at 9pm