Gerd Kempermann in conversation
Recharging your batteries
Frank Haas in conversation with neuroscientist Gerd Kempermann about getting old and staying new.
For the moderately educated layperson, the brain is a very complex matter. What’s it like for you as a professional? Considering everything you have learned, has it become even more complicated or are you resolving its many mysteries?
A bit of both. The more you know, the more questions you have, of course. And in the sciences you soon find out that, for some things, there are no answers – yet for others there are clear explanations. You may have the occasional victory along the way, when you discover something that had previously been misunderstood. All in all, however, the brain is incredibly complex, and, when it comes to understanding it, we are still really scratching at the surface. But that’s what makes it so fascinating.
The aging of the brain is your main field of research, and you focus on an area called the hippocampus. And this hippocampus is flexible?
Not just flexible. More like plastic and malleable as well. Unlike a computer, a brain under goes constant reconstruction. And if this process grinds to a halt, then the brain as a whole stops working too. Interestingly, there is one region of the brain that is also known as the “gateway to memory.” That is the hippocampus you referred to, and it is particularly malleable. All the information we receive and absorb has to be processed there if we want to store it. And what distinguishes this central region of the brain is the fact that it produces new nerve cells throughout life. These new nerve cells are called neurons, and the process is known as neuro genesis. The rest of the brain lacks this ability, which is why degenerative diseases are such a problem: nothing grows back. You can donate blood and soon you will have your full complement again. Or you might go to the hair dresser’s once a month because your hair keeps growing back. The skin’s stem cells continuously regenerate. The intestine is another organ that constantly renews its cells. The brain doesn’t do that, with this one exception. The renewal in the hippocampus is not the replacement of something lost, though. Instead it’s a continuous process that never stops adapting its network of neurons in this region until the day we die.
How exactly can I best visualize this? In concrete terms, which functions can I acquire or extend?
The hippocampus is the place where information is fi ltered, where it is processed, compressed, and structured chronologically in a way that allows us to adjust fl exibly to our environment and our experiences. That’s a very special feature of the human brain: it helps us adapt well to changing circumstances. The human race is able to colonize the whole planet, from areas at the poles with sub-zero temperatures to scorching hot regions, because we possess a high level of cognitive fl exibility. As our geographical range increases, so do the cognitive challenges entailed. The more we move around, the more we have to remember – about what is happening currently and which information we have received. And we need to be able to orga nize this information by its time. This is called episodic memory. The hippocampus is also responsible for this function. For example, in order to fi nd our way back to a place we’ve been, we need to replay the turns and directions we have taken backwards. In other words, we need to keep things in order. Storing memories in a chronological sequence is extremely important for humans because it lays the foundations for our autobiographical memory, without which we could not conceive of ourselves as people at all. To a very large extent, we are composites of our pasts, and we depend on our ability to remember to be ourselves. It’s horrible to see dementia patients losing track of their own biographies. They do not lose their dignity or status as human beings, but they lose sight of themselves as human beings.
We have now discovered that it is these regenerating neurons that make flexible adjustments possible, enabling us to distinguish between what is old and new, even when there may be very little difference in time between them. If you leave your car in a large parking lot every day, but not necessarily in the same spot, you always have to remember where it is. You don’t have to memorize the entire lot every time; you just need to update your internal map. Information on where you parked earlier then becomes obsolete, although the brain still retains it. The capacity to differentiate between current and past information, and to adapt to it flexibly, is a function of the hippocampus, particularly of these new cells.
Gerd Kempermann is a professor at Dresden Technical University and director of the German Center for Neurodegenerative Diseases based in Dresden. In his research, the neuroscientist is chiefly concerned with sustaining brain functions.
So if my hippocampus ceases to function properly, I won’t be able to find my car?
Exactly. Very often the onset of Alzheimer’s, a typical form of geriatric dementia, takes place in the hippocampus and manifests itself in losses of memory. Many other brain functions might still be perfectly normal. By contrast, other forms of dementia tend to start with problems of social interaction, while the memory still keeps working as before. The symptoms depend on the brain regions affected.
But doesn’t the hippocampus begin to deteriorate either way during the course of a lifetime?
Use it or lose it, that’s the golden rule. Anyone who has passed the 45 or 50 mark will notice a slight change in their ability to remember. Most of the time it isn’t serious; your memory just doesn’t work quite as well as it used to. For the most part, people can still manage for an extremely long time without facing serious consequences. They do notice the differences, particularly the older they get, but then they simply devise strategies for coping. Alzheimer’s dementia, however, causes far more damage than the typical losses in brainpower. And the degree of decline varies from individual to individual, and hence also the ability to deal with it. For example, people who lead very active lives keep their batteries fully charged, which allows them to function longer before they start to go flat. Someone with less in reserve will experience more severe problems more quickly. We are trying to understand this phenomenon, i.e. how to stop age-related cognitive loss. We know that it’s possible. What we don’t know exactly yet is who benefits from training and, above all, to what extent they benefit. Training is actually the wrong word. It’s more about staying active and how that protects us from Alzheimer’s disease, which primarily affects the hippocampus.
How would you define staying active in concrete terms? What can we actually do?
We know from major studies that physical activity, education and a balanced diet are the aces in the pack. Of course, there are highly educated people who get dementia as well. But as a general rule, education offers a relatively solid line of defense. You may not be able to prevent the disease, but if you can at least postpone the outbreak of symptoms, that is already a bonus and you might still have a few good years left. If I live to the age of 95 and get dementia at 93 rather than at 88, then that’s a big plus! So staying active doesn’t actually treat the dementia, but I improve my prospects of managing the condition.
What role does physical activity play?
Physical activity is the super factor per se; the traditional saying that a healthy body keeps you healthy of mind still holds true. And it doesn’t entail excessive amounts of exercise. All that’s really required is a degree of movement, a basic level of activity. That’s because the brain originally had the function of facilitating movement. Physical and mental activity were inseparable. Speaking is a form of movement too. And the brain areas that control motor functions are even activated when we are only thinking. So movement is likely the correct fuel for the brain. By contrast, decoupling mental from physical activity might be human, but ceasing to extend our range of movement, and picking up a book, sitting at a monitor and letting the world come to us instead, is actually completely unnatural. Of course, that doesn’t mean there’s anything wrong with reading in a comfy armchair. But there’s a lesson we would do well to heed. People who spend the whole day seated become mental couch potatoes too.
So would it be possible not only to slow the aging process but even to rejuvenate the brain by subjecting it to specific stimuli?
That we don’t know. There’s the concept of “cognitive reserve” in psychology, according to which you have, so to speak, an optimum that you can maintain for a while but can’t exceed. Education during early childhood is key to achieving this maximum. In other words, dementia prophylaxis begins in kindergarten. Supposedly, people then reach their peak during their mid-20s. Pessimists believe that it’s all downhill from there, although we remain oblivious to the changes. However, the more fully your cognitive batteries are charged, the slower the decline is and the further you can go. Ultimately I don’t believe you can get more out of your brain than was originally there. For me, the challenge is rather about maintaining what I have by using it in the best possible way. Of course, occasionally I can still learn things that I couldn’t before. That much is clear. But it seems unlikely that we can create something completely new at an advanced age if the foundations for it have not been laid in the brain earlier. However, this thesis is somewhat undercut by the generation of new nerve cells, because there really is something structurally new here. Indeed, in its filtering function, the hippocampus needs to become increasingly complex as we grow older, for the simple reason that we see more and more, and have to manage mounting quantities of experiences and memories. The new cells play a vital role in this process. Yet here again the formula “use it or lose it” applies. If I have never experienced anything complex, at some stage the muscle will degrade and I will lose the ability to cope with complexity when I do encounter it.
But now we’re living in the age of digitalization and virtuality, and our hands aren’t being used in the complex ways they once were.
Numerous studies of virtual reality and screen usage have shown that displays can replace reality quite effectively. And, of course, there are things I can learn in simulations that would be impossible in real life. That too is testament to our incredible cognitive flexibility. The greater problems are the pressure to be constantly available, the endless multitasking, and the fear of missing something because people are trying to reach you on multiple channels simultaneously. That’s where our systems start to fail.
What about playing musical instruments? Isn’t that a great form of exercise?
Yes, absolutely right. Music is something very unique that only human beings have really produced in this form, a very special capacity of our brains. Beyond its social, communicative, motor and sensory elements, it also has spiritual and mental dimensions. Singing or listening to music together can be a very primeval experience. Dancing is also good. It’s more than likely that music is an excellent vehicle for producing the activity we need to keep young. We’ve now discussed a variety of factors that can help us to success.
But what about diets? Is there such a thing as a brain superfood?
Let me put it in simplified terms: if my body weight remains within a normal, reasonable range, then there’s a good chance that my metabolism is OK. And if my metabolism is OK, then my brain is likely to be doing better too. We also know that antioxidants help in some way, as do omega-3 oils and so on. But none of the studies trying to prove as much are making much progress. That’s presumably because we wouldn’t normally consume all these things on their own, even if they often feature as ingredients in high-quality foods. We don’t simply swallow fish oil capsules and otherwise abandon nutrition in our diets. All these small steps usually simply reflect an awareness of the issues, our personal taste, or the conscious decision to maintain a balanced overall diet. As with choosing the right type of physical activity, the challenge with choosing food is to develop a sense of what is right for me personally, of how I can nourish myself sensibly as an individual. That doesn’t mean you can’t cut yourself some slack occasionally. You need to steer a generally steady course that is reasonably adequate. If I do my own cooking, use lots of greens, less sugar and little meat, then I still have a huge range of dishes that are basically suitable for my body. And I’m probably giving my brain a treat as well.
In light of your own scientific knowledge and experience, what do you never want to stop and what would you still like to start doing?
What I never want to stop? That’s a great question! I’d like to be able to play piano and am already working on that. And I’d like to keep myself mobile, including outdoors. It’s absolutely correct that we shouldn’t wait until retirement to try something we want to do. We should keep striving in the here and now, and create a sense of continuity. This notion that you could engage in some regime of mental exercises that allows you to start learning Italian at the age of eighty is something I find strange. It isn’t a sensible approach in my view. I need to be living my life today in a way that lets me learn Italian when I’m old, if I want to. In other words: it’s best to get started right now.
Frank Haas is Head of Brand Strategy and Communications at Gebrüder Weiss – and editor-in-chief of ATLAS.