Dr. David Eagleman

The key is to actively seek those challenges and seek new things and seek to become expert in various sorts of fields.

And I think the key is that once you become good at something, you have to drop that and take on something you're not good at.

This is the best thing you can do for your brain.

The reason is because what you're doing is you're constantly building new roadways and pathways in the brain.

There's a study that's been going on for decades now called the Religious Orders Study, where a bunch of Catholic nuns agreed to donate their brains for autopsy when they passed away.

What the researchers discovered when they look at the brain carefully is that some fraction of these nuns had Alzheimer's disease.

Their brains were physically degenerating with the ravages of this dementia.

But they didn't show any of the cognitive deficits that one normally has.

They didn't seem to be having memory problems and so on.

It turns out it's because all these nuns lived in these convents till the day they died.

They had social challenges and they had fights with their fellow sisters and they played games with their fellow sisters and they had chores and responsibilities and they were doing stuff.

What that means is even as the tissue, the brain tissue, was physically degenerating, they were making new roadways and bridges all the time.

And so that's what kept them cognitively healthy.

We call that cognitive reserve.

Contrast this with people who retire at 65 and they go home and they watch television and their social circle shrink and so on.

That's when you've really got concerns because you're not building the new pathways.

Almost certainly with cognitive decline, because you're just not getting the challenge.

At that point, you're just coasting on your internal model.

It's tragic.

But what happens often is that people's hearing gets worse.