The Brain Professor: "Popular Treat Now Considered Deadlier Than Smoking!", "Alcohol Is Shrinking Your Brain" - David Raichlen

David Raichlen (0:00)

If you sit for 10 hours a day, compared to 9 hours a day, it's about a 10% increased risk of dementia. If you sit for 12 hours a day, it's about a 60% increased risk of dementia.

Steven Bartlett (0:10)

60%.

David Raichlen (0:11)

Yes. So it's a problem that we have to deal with.

SPEAKER_3 (0:14)

David Raichlen, Professor of Human Evolutionary Biology, Exercise Physiology and Neuroscience at the University of Southern California.

David Raichlen (0:22)

We are dealing with brain health problems that are only going to increase as our population ages. And healthy aging is linked to three behaviors. Diet, physical activity and social connections. For example, people who have stronger social connections tend to have better brain outcomes than people who don't.

Steven Bartlett (0:39)

Does excessive alcohol use to shrink the brain?

David Raichlen (0:41)

Yes. Over one drink per day is associated with negative health outcomes.

Steven Bartlett (0:45)

Sleep is the other one that's a big factor in cognitive decline, right?

David Raichlen (0:48)

It is. Less sleep and lots of sleep are both associated with higher risk.

Steven Bartlett (0:53)

Is there an optimal amount of exercise?

David Raichlen (0:55)

Physical activity guidelines are 150 minutes per week, but only 25% of adults in the US meet those guidelines with older adults doing 2 to 4 minutes per day.

Steven Bartlett (1:04)

2 to 4

David Raichlen (1:05)

But there are these small activities that provide big benefits, that generate new neurons and those neurons get integrated into key parts of the brain. Number one is, remote work is dangerous. It's unnatural for the human body.

Steven Bartlett (1:19)

I'm concerned about physical health. What's the practical advice to people that work at home that is realistic for us?

David Raichlen (1:24)

If you combine with, it will literally change your life.

Steven Bartlett (1:38)

David, if you had to summarize the essence of what your work shines a light on and what it intends to help us understand as human beings, how would you summarize that?

David Raichlen (1:48)

What my work has been focused on is understanding how and why physical activity especially and lifestyle behaviors in general can impact health and most specifically impact the health of our brains. And I think that, you know, we are dealing with brain health problems that are only going to increase as our population ages. So we have 6 million people in the US today that are diagnosed with Alzheimer's disease or other related dementias. That's projected to grow to around 13 million people over the next 25 years or so. We're projected to have 150 million people diagnosed with dementia worldwide over the next 30 years or so. So it's a problem that we have to deal with. My work has been focused on ways that we can prevent these diseases that are associated with aging.

Steven Bartlett (2:46)

Why does the brain matter? And I say this in part because I think for most of my life, I just assumed, you know, I understand muscles. I can go to the gym and work on my muscles, but the brain I just thought is this like piece of tofu in between my skull that I have very little control over.

David Raichlen (3:01)

Yeah. I mean, I think that was the prevailing view for a long time, that we grow our brains as children and during adolescence, and by the time you're in your 20s, your brain has done all the growing it's going to do, and now it's just this progressive shrinking over the rest of your life. And over the last few decades, we've realized that's not true, actually, that you can generate new neurons, especially in key areas of the brain, like the hippocampus that's associated with memory, and that growth of new neurons may be the key to preventing or staving off these neurodegenerative diseases that have this big impact on the aging brain. And so, you know, if we can find ways to do that, and what I study is kind of doing that through physical activity and exercise, then we might be able to prevent some of the cognitive decline people experience with aging, maybe even stave off or prevent the development of Alzheimer's disease or other dementias.

Steven Bartlett (4:02)

What evidence have scientists got that we can actually grow our brain?

David Raichlen (4:08)

Well, that's a great question. The evidence in humans is a little trickier, so I can talk more about the evidence from animal models, because with animal models, you can actually look inside the brain and see what's happening after, say, an exercise intervention. So there have now been many, many studies, especially in mice and rats, where researchers have shown that if you give them access to running wheels or if you have them run on a treadmill, that you actually generate new neurons, and those neurons survive and get integrated into key parts of the brain. And we focus a lot on the hippocampus because it's so important to memory, which is a major aspect of being human, is being able to remember things. And researchers have shown very clearly that exercise and physical activity in these rodent models leads to the birth and survival of new neurons.