Brain plasticity – the idea that the brain is far more than a mere computer that slowly dies as we get older – is possibly the most stunning reversal of knowledge in the late 20th century. And yet it is still mostly unknown to many people, who have been brought up on the previously accepted concept that learning effectively stops beyond the age of twenty, after which brain cells simply start dying.

The brain, we now know, is a plastic, ever-changing organ. It responds, like other organs, to use. And if you don’t use it you lose it. This goes for memory, recall and cognitive skills. The human being is, we now see, a learning machine, designed to keep active all our lives. In our ancestral past survival relied on knowing the way to food sources, the location of safe places and where and when water could be had. Those who couldn’t learn this, those who forgot the way home, soon got eaten…

So it is little surprise that Dr Merzenich, one of the world’s leading experts on stroke recovery, should be so opposed to using something like a GPS. Indeed, location finding is such a central part of brain function and so important to arresting cognitive decay that he refuses to use a GPS himself and alternates walking different routes home in order to keep his mind switched on and learning, rather than idling and passive.

‘On’ is more than just a metaphor. When we are children, the brain is always open to learning, but as we progress into adolescence it controls increasingly what we learn. We develop an ‘off’ switch for things deemed beneath our interest. When we are ‘on’ neurotransmitters and hormones associated with brain growth are released. As we grow older it seems that we stimulate actual physical change in our neuronal structure – change that can be viewed microscopically – only when we are shocked by something, see something new, or engage in focused paying of attention (typically through focused repetition). Humans love novelty – a trait exploited by shopping outlets – but the reason is very real: our brains thrive on it. People who travel to new places, who keep learning languages and experiencing new things into old age, are far less likely to develop cognitive decay.

The fascinating thing about brain plasticity is that we can teach ourselves to not learn. If we habitually do not pay attention, if we allow ourselves a fuzzy memory of an event, if we fail to seek a satisfactory explanation for something, allowing it simply to drop from sight, then we are actively barring our ability to learn. People who keep journals, especially those laced with photographs, show much better recall as they grow older. Rehearsing their memories as they construct their diary requires them to focus and repeat, switching on the capacity to learn.

The work Dr Merzenich did with stroke victims revealed the extent to which the brain can regrow after the massive damage of a stroke. The principles he derived from this work form a guiding basis for cognitive health. People wishing to maintain this are advised to:

  1. Increase your ‘spark’: be more alert and focused on all you do.
  2. Work on your ‘happiness machinery’ a little each day. A positive mood is shown to aid brain growth and health.
  3. Set yourself memory and learning tasks
  4. Be accurate. Sharpen speech rather than allow it to become sloppy.
  5. Suppress noise and distraction.
  6. Navigate in time and space. Recording and manipulating where we are and where we have been is a core brain activity.
  7. People skills can drop off as we get old and cranky, and yet charm and manners not only make others happier, they keep the brain sharp. ‘Letting it all hang out’ reduces focus, which is a poor learning strategy.
  8. Encourage flexibility in intelligence. Actively embrace contradiction and incongruity: it challenges the brain to grow more.

There are other books about brain plasticity that are certainly worth reading – Norman S. Doidge’s The Brain that Changes Itself is already a classic in that realm – but Dr Merzenich, though less fluent, offers up the learning of a lifetime in the elusive study of how we learn best. There are quite a few received ideas (such as the belief that doing crossword puzzles aids cognitive health – which is disputed). And although some concepts about what aids brain health seem obvious, that isn’t the case with all of them. What does come over, though, is the overwhelming need to do as much ‘training’ in learning as we are encouraged to do with our physical bodies. Indeed, it may surprise us in the future to discover that being a lifelong active learner is even more important to longevity than pumping iron down at the gym.