Daniel Levitin is a neuroscientist and this is a book about the human brain as it gets old. Levitin tells us what happens, why it happens and what you can do about it. Well, what can you do? The short answer: eat real food, get a proper night’s sleep, walk in natural environments and make sure your brain is always working. He quotes Keynes: “In the long run, we are all dead.” True. Still, we don’t need to be so passive. We can put up a fight.
So the book has an optimistic tone. Levitin tells us about age-defying people such as Mick Jagger and Jane Fonda — Jagger has a personal trainer and dances a lot; Fonda walks and lifts weights. Then there are the “blue zones”, places that produce lots of people who live beyond a hundred years — “Nicoya, Costa Rica; Sardinia, Italy; Ikaria, Greece and Okinawa, Japan (some lists add Del Mar, California)”.
What happens in these places? Old people do lots of healthy things such as walking and gardening, they have many human connections, they eat real food and avoid stress. Of course they die in the end. But something is keeping them alive and healthy for longer.
Levitin thinks about what the brain needs to do when we’re young. It constructs our world for us. As we interact with our environment, our brains retain all the data that is useful to us. The world we see is not the world as it is — it’s the world as our brains want it to be. The brain constructs the world for us.
Of course, there comes a point when the brain goes wrong and our world starts to deconstruct. It’s the old story, when we get too old to reproduce, nature no longer has much use for us. Having meticulously constructed the world in our heads, at some point our world begins to fall apart.
There’s a very good section on memory and how our memories are not fixed. They’re a work in progress. In other words, they are malleable fiction, rather than stable fact.
We tweak and spin things to help us get through life. Also, “they are not stored in a particular place. Memory is a process, not a thing”. It is created by getting out there and interacting with the world, collecting data and trying to observe patterns in the data. That’s what the old people in Okinawa are doing. They are still learning. We see why it’s better to walk in the wilderness than in a park. In the wild, your brain learns something new with every step you take.
Levitin loves to tell stories. He’s a good companion. He tells us about when he walked around wearing distorting lenses to see if his brain made compensations (it did). As we get old, we can’t see or hear so clearly but the brain uses its experience to improvise. In the end, things are not so great. Our brains start to go wrong, then our world falls apart, then we die.
But still, there are things we can do. He cites the sleep guru Matthew Walker — one reason we need to sleep properly is that, as we sleep, our brains are cleaned by cerebrospinal fluid. He also cites the food guru Michael Pollan who says: “Eat food. Not too much. Mostly plants.” By “food”, Pollan means whole, rather than processed.
So, eat like a scientist. Exercise adventurously. Sleep like a baby. Make your brain work hard. Have lots of friends. “And allow yourself to have fun now and then,” Levitin advises. “Eat a little ice cream. Have some chocolate.”
The Changing Mind: A Neuroscientist’s Guide to Ageing Well by Daniel Levitin (Penguin, £18.99), buy it here.