"Let me live, love, and say it well in good sentences."

I have written about how the disease presents in a person, my experience of caring for my mother, the causes, my quest to find a cure or treatment that might slow it, and the lifestyle modifications we can make to protect our brains.

Alzheimer’s and other dementias don’t suddenly descend in age, says James Rowe, Professor of Cognitive Neurology at Cambridge. “They develop, hidden, over decades, like a slowly brewing storm.” From midlife, that pathology accelerates “and eventually breaks cover, overwhelming the brain’s ability to compensate.”

Brennan introduces her book with a poem which explains the title and reminds us of the central themes of anybody’s dementia journey:  I have dementia and I am still me, and I care for you and I am still me.

Photographs of my mother, hers, me cradling my newborn son against me (“Look! Four generations,” we’d laughed that day). Mum carefully considers this little group, standing smiling on the back step of a home bathed in September sunshine: “There’s my mum!” she said.

Then, pointing at me: “Who’s she?”

Mum’s depressions started in her thirties. How much of a role did they play in the dementia that revealed itself in her seventies? There are several compelling hypotheses that suggest one drives the other.

A study published this week suggests that statins might be the latest to join the arsenal against Alzheimer’s. It’s a tablet millions of people pop daily, my husband among them. My mother, who died of dementia, also took statins — but only after having had a stroke in her seventies. Is it possible that had she taken them earlier in her life, she would have been spared from the development of this cruel disease?

The author enlists her investigative journalism skills to understand her mother’s illness and, later, to learn how she might save herself from the same neurodegenerative fate.

Dementia may feel like a wrecking ball, but it’s not simply absent one day and fully present the next. No, it settles in, makes itself at home and lingers in the shadows for 10, 15, or even 20 years.

I watched my mother draw a clock while she was in a brain rehabilitation centre after her stroke. Until then, I did not know how common a test it was, how often it was used – or why.

The clock drawing test – or CDT – is used regularly to assess several mental processes. Over the past two decades, it has become a key tool in early screening for cognitive impairment – especially dementia.

You might expect it to be simple: drawing a clock that shows the time, say, at six o’clock: a circle, numbers, a big hand, a little hand.