Three enjoyable ways to slow your brain's ageing - BBC

If presented with an easy task or a hard one, which would you take? Chances are we'd all pick the easy task, for good reason. Taking mental shortcuts is built into our biology in order to conserve our energy.

Technology has only enhanced our ability to do so. It's therefore tempting to take shortcuts and complete tasks with the least friction possible. However, if that results in reduced mental effort it could be harming our lifespan and overall health.

Our " healthy lifespan " – the number of years people spend in good health – is declining in many parts of the world. As people live longer, the number of years they live in ill health tends to increase, researchers note.

When it comes to the brain, there are things we can do to promote a longer healthy lifespan. Essentially, if we take part in challenging activities, we are building up what's known as " cognitive reserve " – which has a protective effect on the brain.

There are numerous ways to do so as part of everyday life. "Whatever age we are, there are things that we can do more or less of that might give our thinking skills a bit of a boost," says psychologist Alan Gow from Heriot-Watt University in Edinburgh, Scotland.

One strategy to protect against age-related cognitive decline is to target a specific part of the brain. The brain area important for spatial navigation, the hippocampus, is believed to be the first part of the brain affected in Alzheimer's disease, several years before symptoms start to show.

"For years we've known that people with Alzheimer's often get lost as an initial symptom," says neurologist Dennis Chan from University College London, UK, who specialises in early Alzheimer's detection. And early detection is crucial, he says. "The earlier we identify [cognitive impairments] the faster we can do something about it."

Protecting this brain area could therefore help prevent or delay symptoms. For instance, studies show that ambulance and taxi drivers have among the lowest rates of Alzheimer's-related mortality compared with other roles, precisely because these drivers had been using their brain more for "spatial processing", the researchers propose. It's also long been known that taxi drivers who had spent years learning the city's streets without the use of a map, have an enlarged hippocampus.

Similarly, one study of healthy men who performed a spatial navigation task for four months showed improved navigational skills and no loss of hippocampal volume, whereas the control participants (those who did not perform the task) did experience expected age-related shrinkage.

It's unclear whether enhancing this part of the brain could prevent dementia, but building extra cognitive reserve could offer extra protection. This helps explain why, as Chan says, post-mortem brain analysis has shown that some elderly individuals had extensive Alzheimer's-related changes in their brain tissue yet showed no symptoms while alive. One reason why, he says, is because their scaffolding must have been robust – potentially helped by the way they lived, though genetic factors are also believed to play a role.

And despite the increasing risk of dementia as we age, it's those who do not show symptoms that Chan says should be encouraging for all of us. "They are generally those who are physically active, more intellectually active, and those who are more socially active."

We can all work at enhancing our spatial skills too with sports like orienteering or, in children, playing with building blocks. Working out directions without using the map on your phone could also help – as using GPS has been linked to poorer spatial memory. There are also computer games that could help if carefully designed. One small trial in older adults found that those who played a virtual reality spatial navigation game helped improve memory, for instance. However, this was a game designed by researchers, so it does not mean that your favourite computer game is going to improve your memory.

In line with that, numerous lines of research have shown that staying socially active protects us from cognitive decline. Centenarians with higher social engagement have better brain health, for instance, while taking part in social activities during midlife has been associated with higher overall cognitive ability in old age. ( Read about why later life can be a golden age for friendship.)