The Stimulated Mind

A group of scientists from Harvard analysed data from modern hunter-gatherer groups and found that grandparents were at least as active as parents, often hunting and gathering for several hours per day. Older adults in those societies who were in their seventies and eighties were still three times more physically active every day than the average U.S. adult is at any age.

The loss of the cognitive and social stimulus our brains get from the work environment is probably why retirement is often the point at which cognitive decline accelerates.

Because one big driver of cognitive decline seems to be our own expectations. Over time, we expect less and less of ourselves because we think our ageing brains are no longer capable of what they once were. We therefore use our brains less or offload difficult tasks to technology or other people. As we do less, the brain responds by decreasing its own capacity.

The brain, though, is exactly like a muscle; the more we exercise it, the stronger it becomes and the better it works, regardless of how old we are. Reframing what we expect from our brains therefore sets the scene for them to be healthy and happy in the long term.

Collecting your gold watch and enjoying long days in your favourite chair doesn’t suddenly result in a huge accumulation of amyloid in the brain. Instead, it’s the removal of the complex cognitive stimuli we get from our work and interacting with our colleagues that stops our brain continuing to make regular repairs. And as a result, our brains become less and less roadworthy.

In the past few decades, however, it’s become increasingly clear that the brain is amazingly plastic—a fancy neuroscience word for adaptable and changeable—even in old age. We just have to give it the right inputs and tools to make it adapt.

Studies show that learning new skills or engaging in creative activities (art, languages, music, and even video games) can slow or reverse changes in brain networks that are susceptible to ageing.

Exercise is another perfect example of this—it is the only intervention that seems to either slow or reverse every biochemical hallmark of ageing.24 And, amazingly, exercise can also measurably improve the brain’s neuroplasticity.

What the study found was that our ability to perform complex skills is much more related to how we use our brains than it is to how old our brains are.

The stereotype-embodiment theory suggests that if we expect to lose cognitive function as we get older, we will see greater cognitive decline with age as a result. Some of this is due to the subconscious effects of expectation, but some of it is also a direct result of the activities we choose to engage in, or not, as we get older.

If we expect to lose function as we get older and, as a consequence, stop exposing our brains to the conditions and environment that drove their development in the first place, it’s the removal of those stimuli that drives the loss of function with age rather than the other way around.

The combination of challenging your brain with cognitive activity plus a good diet, regular exercise, not smoking, and not drinking too much seems to be associated with a 50 percent reduction in the risk of dementia!

What the study found was that only longer unbroken periods of being sedentary were associated with higher dementia risk. Put another way, if we accumulate a lot of time not moving during the day—which we often do for work or while we relax—it seems that we can offset that simply by breaking it up.

For each additional thousand steps you do per day above fifteen hundred, the risk of dementia decreases by around 7–8 percent, and the overall risk of dying decreases by around 15 percent.31 Walking, therefore, is a low-risk, free, and easy way to add brain-supporting movement to your day.

Once walking is “brisk” (at least 2.5 miles per hour or one hundred steps per minute), it counts as moderate physical activity. The amount of moderate-to-vigourous activity that people do in a day is one of the best predictors of their daily cognitive function.

Adding thirty minutes of moderate physical activity per day might even be enough to overcome most of the health risks associated with being sedentary the rest of the time.