Downstairs, the boys gaze at a screen on the old futon in the playroom. We will figure out what to do about them soon enough. They probably already know what’s up and are waiting for us to figure out how to say it. Their very existence is the one dark piece I cannot get right within all this. I can let go of a lot of things: plans, friends, career goals, places in the world I want to see, maybe even the love of my life. But I cannot figure out how to let go of mothering them.

And I spent four years at a boarding school in the country, probably a rather abusive boarding school, and seeing very little of my parents, and that was a very bad time for me. A bad and almost a mad time. ... I think that some sort of trust, and ability for closeness, may have been compromised. And I think I’ve perhaps, to some extent, sort of kept a distance since that time, although this is not a distance I feel with my patients or my students.

Writing became a therapy. First of all, it meant I was reconstructing my own existence. It was also an act of defiance. I wasn’t supposed to write. ... I evolved all kinds of mental exercises, even went back to those subjects which I said I hated in school, in particular mathematics. ... You know, anything to keep the mind alive.

It went past being hungry; it was actually painful in your stomach. I could feel my intestines twisting in the middle of the night. I would scream to my grandmother and she would get me sugar water and it would settle it down. A lot of my values come from being resilient. The people from my community might be poor financially but they are happy, proud and resilient people.

Let us consider me as a test case. As I have said, I would like to die peacefully with Thomas Tallis on my iPod before the disease takes me over and I hope that will not be for quite some time to come, because if I knew that I could die at any time I wanted, then suddenly every day would be as precious as a million pounds. If I knew that I could die, I would live. My life, my death, my choice.

I remember what George said and vowed that rather than let Alzheimer's take me, I would take it. I would live my life as ever to the full and die, before the disease mounted its last attack, in my own home, in a chair on the lawn, with a brandy in my hand to wash down whatever modern version of the "Brompton cocktail" some helpful medic could supply. And with Thomas Tallis on my iPod, I would shake hands with Death.

When my father was in his terminal year, I discussed death with him. I recall very clearly his relief that the cancer that was taking him was at least allowing him "all his marbles". Dementia in its varied forms is not like cancer. Dad saw the cancer in his pancreas as an invader. But Alzheimer's is me, unwinding, losing trust in myself, a butt of my own jokes and on bad days capable of playing hunt the slipper by myself and losing. You can't battle it, you can't be a plucky "survivor". It steals you from yourself. And I'm 60; that's supposed to be the new 40.

Did the Victorians fear death? As Death says in one of my own books, most men don't fear death, they fear those things – the knife, the shipwreck, the illness, the bomb – that proceed, by micro seconds if you're lucky and many years if you're not, the moment of death.

It occurred to me that at one point it was like I had two diseases – one was Alzheimer's and the other was knowing I had Alzheimer's. There were times when I thought I'd have been much happier not knowing, just accepting that I'd lost brain cells and one day they'd probably grow back or whatever. It is better to know, though, and better for it to be known, because it has got people talking, which I rather think was what I had in mind.