While speaking on the importance of lifelong learning at the Seoul Future Learning Forum on July 12, I was asked a question that everyone in our society should ponder. The gist of the question was, how do you advise teenagers to accept the need for lifelong learning in a country where it is common to think that young people only study hard until they get into a good university, and then they want to have a comfortable job and live with as little pain in the mind and the body as possible? In a way, the question hit home about the general thinking of Korean people after the nation’s rapid economic growth period -- the idea of doing things faster, easier, and ultimately making money.

My answer to this question is simple. If you stop learning early and give your brain a break, you might just end up in old age with dementia sooner. If you stay in bed for long periods without using your muscles, you may not have the minimal muscle strength you need to walk later in life, and you won't have a chance to regain it. Similarly, if your brain is constantly resting without working, your "cognitive reserve" will diminish.

To understand this, it's important to review the concept of cognitive reserve. It can be described as "brain muscle strength.” A person who barely has the strength to walk can't get out of bed after a few days of pneumonia, and the minimal activity required to maintain that strength becomes even more difficult. They have little muscle spare capacity. However, if you have a good muscle reserve, once you get out of bed and start walking, you'll quickly recover and get back to your normal physical activity because the act of walking is an exercise in itself. So, if you don't have the strength reserves you've built up, you could end up spending the rest of your life in bed. The difference between the minimum strength you can walk and your current strength is your functional reserve. It's a bit like the electricity reserve that we hear about every summer.

The same goes for the brain. If you use your body and brain in a variety of ways throughout your life and take good care of your cognitive functions, you have a relatively high cognitive reserve. If you have enough cognitive reserve, even if you accumulate a significant amount of structual alterations in the brain, your cognitive functioning will still be sufficient to carry out your daily activities and you may not suffer from dementia. So you can think of it as your brain's “bank account balance,” and if you build it up over the course of your life, you'll be able to maintain a good quality of life even if aging or disease leads to pathological problems in the brain.

Many studies have shown that how we use our brains throughout our lives has an impact on dementia development and structural changes in the brain. One famous study found that taxi drivers in London who had to memorize maps and addresses had enlarged hippocampi compared to bus drivers. Some studies show that people with jobs that require complex and cognitively demanding tasks are less likely to develop dementia. A study, led by Professor Ross Andel and his colleagues at the University of Arizona in the U.S., found that people with jobs that involved human contact, such as managing and counseling people or serving customers, and collecting, sorting, and analyzing information had an average 22 percentage points lower incidence of dementia than people with less cognitively challenging jobs.

Taken together, the research on dementia risk suggests that activities that can help build cognitive reserve include physical activity, cognitive activity, and social activity. Consistently performing cognitive tasks that are complex, mentally demanding, and uncomfortable can improve cognitive function. It's interesting to note that in these studies, the effects of physical exercise are similar to those of cognitive activities that use the brain, and activities that use both the brain and body, such as dance, are known to be particularly beneficial. In particular, researchers like Professor Emily Rogalski, who studied "super-agers" (people who age very healthily) with very young brains well into their 70s and 80s, found that people with slow-aging brains were also more likely to be physically active, cognitively active, and socially active.

The harder you work your brain, the better your cognitive function, and as a result, the more you work your brain, the more good stimulation it receives, and the more new connections are made between nerves. It's the same principle with muscles. Climbing stairs is hard at first. But as your strength improves, you'll be able to climb stairs more and more effortlessly, get more exercise, and get stronger, creating a virtuous cycle. If you don't use it, you lose function, and if you lose that much function, you lose your life.

From the perspective of cognitive reserve, those of us who will live to be centenarians will likely be studying for life, working for life, and creating a life that resembles being retired all the time. There are many reasons why the traditional life cycle of staying in one job after formal education and retiring at a certain point to spend the rest of your life relaxing may not work as well now. Your primary source of income is constantly changing as technological innovations eliminate jobs and create new ones. Adapting to the new world of technology requires a lifetime of learning.

As a society, we need to move away from the old view of economic activity in later life as a consequence of poverty. Studying and working throughout life is a preventive measure against dementia and frailty. Even the smallest job or volunteer work is good. It requires getting out of the house and going somewhere (physical activity), performing tasks (cognitive activity), and interacting with people (social activity).

In that sense, the Korean college entrance examination system and the study methods that have been adapted to it are anachronistic. The hypothesis that you can spend more money on private education and study harder for a short period in the early years of your life, and then earn an easier income from then on, and live a lifetime without physical and mental hardship is unlikely to work. A healthy and happy 100-year life is built on a lifetime of discovering what matters to you and what you enjoy, and the constant physical and mental effort invested in pursuing those passions. Each of our lives is a work of art to be sculpted throughout our journey.

Jung Hee-won, a geriatric physician at Asan Medical Center, graduated from Seoul National University College of Medicine and trained at Seoul National University Hospital. During his med-school days, while practicing the horn, he realized the importance of muscle maintenance and became interested in sarcopenia. His main research interests include frailty, sarcopenia and establishing age-friendly health systems for acute hospitals. This column was originally published in Chosun Ilbo in Korean on July 26. --Ed.