There can’t be many people who spend years angering and grieving the death of a parent from dementia, without wondering whether this is what awaits them too.

I am one.

My mother died in 2012 from this life-threatening brain condition. And since then, hardly a day passes when this question is not roaming in my mind, appearing ridiculously every time I put a word, name or pair wrong. Glasses.

In fact, it is quite normal in a busy life to lose your glasses or wonder what you were looking for in the wardrobe.

But tell this to those of us in the next generation of victims, who have seen loved ones suffer in ways we can still hardly imagine. We ask ourselves, is this the beginning of horror again?

Now, for the first time, we can find out for sure.

A simple blood test, taken as part of a research program and where necessary, supported by a lumbar puncture and a PET scan – which produces three-dimensional images of the inside of the body – can tell us whether amyloid, A brain protein that is involved in Alzheimer’s disease already exists.

I made a film about what this means for individuals like me, 50 and 60, who have a family history of Alzheimer’s, the most common disease leading to dementia.

What else? Deciding whether you want to go ahead with it is not that easy.

My mother, Mamie Baird, was one of the pioneering female journalists of the 1950s.

Bright, clever, quick-witted and funny, she was still writing after dinner and giving hilarious speeches at the age of 60.

But like millions of others in the UK, she fell victim to a disease that affected her personality and cognition until she lost her ability to function.

There was nothing to help her: little support, and no medication to ease the symptoms which over time made life a torment for her and all of us who loved her.

Dementia is not a natural part of aging, although the risk increases with age. It is a disease caused by one or a combination of several brain conditions.

My mother was diagnosed with both Alzheimer’s and vascular dementia, and although we spent a lot of time together in the years that followed, there was a lot of laughter and a lot of joy in that moment, the progressive disability and isolation that was so painful for her. It was such that it cannot be expressed in words.

In 2014, I published the book Where Memories Go, a blend of memoir and journalism, describing what the experience is like for families who have to struggle without hope of recovery – and I was stunned by the response.

The thousands of messages I received from across the country felt as if a vast portal of pain and family loneliness was opening.

Now 10 years later, there is hope.

Scientists have shown that amyloid buildup can be successfully cleared in the brains of people with Alzheimer’s.

They are convinced that drugs already in development (and at least one, lecanumab, is now licensed for use in the UK, although not yet on the NHS) could be better if they were given to people before they developed symptoms. If so, Alzheimer’s can be stopped in its tracks. ,

As Professor Craig Ritchie, who runs the leading Scottish Brain Sciences (SBS) in Edinburgh, says: “We can stop Alzheimer’s before it becomes dementia – just as we learned to stop HIV before it becomes AIDS.”

But to do that, scientists like him need thousands of people to come forward for testing before they become aware of symptoms.

This means that people like me, who are still living normal lives and holding down tough jobs, have to be prepared to find out that the Alzheimer’s disease process is already going on in their brains.

Professor Ritchie, whom I originally met during my work at the music and dementia charity Playlist for Life, suggested I join the huge research group he was trying to assemble at SBS.

“Finally, Sally,” he said, “you might equally find out that you are not amyloid-positive. Imagine how much of a relief that would be.”

And if it turns out that I am? If I know that which cannot be unknown, then what?

Treatments are coming, but they’re not here yet. The paradox is that if people like me got involved in research programs like Craig’s they could come in time and save those of us who are now in our 60s.

I asked my family about this.

My four sons think I should go ahead and do it. He says, find out the truth and let’s deal with it together.

But my daughter, who was still in shock after seeing what happened to her grandmother, burst into tears.

She fears that if we discovered that amyloid was hidden in my brain, and there was no immediate means of removing it, knowing this would affect not only our future but also our present.

We are today on the cusp of a game-changing development that, if scientists are right, could soon cure Alzheimer’s.

Biomarkers in the blood will provide an opportunity to identify people at risk and participate in trials of new treatments.

It’s good for them and it’s good for their children and grandchildren. But if these trials cannot be run on a larger scale with asymptomatic volunteers, scientists will not be able to develop this important next step in treatment.

That’s why they need people like me. What should I do? This is what my film is about.

Sally Magnusson: Alzheimer’s, a Cure and Me will be broadcast on BBC Scotland on Sunday 13 October at 21:00. It will also be available on iPlayer,