Jules Montague: If you can remember your childhood, but not your children, are you still you?

Jules Montague is due to speak at the National Museum of Scotland tomorrow

One day, Patrick found his wife’s handbag in the fridge. They had spent the previous half-hour looking for it and there it was. On the second shelf, next to the cream cheese.

As Alzheimer’s disease eroded Anita’s brain, nerve connections malfunctioned, abnormal proteins gathered and neurotransmitters failed. She asked Patrick the same questions repeatedly. Words vaporised and sentences misplaced structure. She muddled up faces and names.

She had noticed the problems first, she said. Before the rest of the family. Occasionally losing things, missing the usual exit off the motorway, searching for words that returned sluggishly to her mind, long after a conversation had ended.

She was just tired, she thought. These were senior moments. She reassured herself, others reassured her.

But soon there was little room for reassurance. ‘I just told you that!’ they told her, exasperated. You didn’t, she argued. ‘I just told you that!’ An accusation and a refrain.

The Bog of the Frogs walk. They did it four times a year.

A three-hour walk that loops up the promenade of the fishing village of Howth, about nine miles north-east of Dublin’s city centre.

Patrick wasn’t able to make it that afternoon – he’d sprained his ankle – and so she went with the rest of the group from book club. Somehow she had fallen behind, lost sight of them for just a moment. Then she was alone, looking at the little purple and green and blue arrows on wooden posts that marked the route and they were pointing to the right one minute and to the left the next.

She decided to try one way, which way she couldn’t remember now, but it was hopelessly wrong. On a small muddy path, the voices of fellow walkers grew distant as panic soared, then another path to nowhere, and another. A man from the golf course had found her, shivering and bawling and unable to figure out how to dial Patrick’s number.

Anita sat in front of me now at the clinic, Patrick by her side. I think they already knew. She looked lost all over again.

She could remember childhood summer trips to Butlin’s Holiday Camp at Mosney: the Holiday Princess Competition. HB cream ices, chalets and treasure hunts. Skirmishes over Lego with her little brother, the time she got given lines for talking in class (‘I am a chatterbox, I am a chatterbox’).

But ask her what she did that morning or the week before and the room swelled with silence.

The temporal lobe takes the hit initially in Alzheimer’s disease, years before symptoms even emerge, its sea-horseshaped hippocampus and entorhinal cortex shrinking away early. Episodic memory suffers – the ability to travel back in time, the capacity to encode, store and retrieve your personal experiences: how you celebrated your birthday last year, what you had for breakfast this morning, where you went on holiday last summer.

Distressing diagnosis

There are other forms of dementia, disorders that affect cognition – things like learning, memory, language, social cognition and executive function – but Alzheimer’s is by far the most common form of all and is the one that typically manifests with this sort of memory impairment as an early symptom.

The disease spreads outwards after that, encompassing the rest of the temporal and parietal lobes and moving towards the front of the brain. You ask the same questions over and over, you misplace things, get lost while walking to the shops. Your family hides the car keys after the morning you swerved into an oncoming car. Your speech is hesitant, halting, you cannot name objects: maybe a saucepan first, then a fridge, then a pen. Gloves become socks, tigers become cats. You cannot figure out ‘how’ – how to button up a shirt, how to change channels. As neurons at the front of the brain are lost, you cannot plan your day or do two things at once. You are anxious and irritable, perhaps depressed and paranoid.

Past and present

This reliving of personal experience also depends on the temporal lobe’s connections with the frontal lobe and the limbic system, among other parts of the brain that play a supporting role in the operation of memory.

Anita’s story was in some ways similar to that of others who develop Alzheimer’s every year, some 47 million worldwide, one new case every 3.2 seconds. Ultimately, age is the greatest risk factor for developing Alzheimer’s and usually the first symptoms begin after the age of 65, around the same age as she developed hers. The incidence of Alzheimer’s doubles every five years after this.

I see plenty of younger patients at my cognitive clinic, too. Whether or not you develop Alzheimer’s seems to depend on a host of genetic and environmental factors, but inheriting risk genes does not guarantee that you will develop the condition.

Around 25 per cent of cases are clearly familial, with two or more family members affected. Similarly, age, obesity, head trauma and high blood pressure are only risk factors for Alzheimer’s; they are not causative in isolation. The thing about Alzheimer’s – all diseases – is that generalisations are only useful to a point. Though the results of her memory tests told a well-worn tale, this particular journey was hers alone. The process of forgetting and remembering is familiar, but Anita’s own memories and personality would shape the trajectory of her dementia.

Despite the gradual transformation of speech and of thought and of being, wasn’t there something of Anita  still present throughout? Wasn’t Anita still, in a sense, Anita?

Anita’s memories, it seems to me, are her story, her continuous narrative, her record of herself.

Those earlier experiences link present Anita to past Anita; they seem to make her the same person.

And this sameness is at the core of identity – the confluence of things that make you you, over time.

And so, really, what I want to understand is this: if we lose our memories, do we lose ourselves?

Dr Jules Montague will be speaking at the National Museum of Scotland at 8pm tomorrow. To book a ticket visit www.sciencefestival.co.uk/event-details/lost-and-found

Lost and Found by Jules Montague, published by Sceptre, £20 is out now