How Walking Improves Memory | Dr. Alan Castel & Dr. Andrew Huberman

Walking & Brain Health

00:00If you go on a walk, some really good research shows that, you know, walking three or four times a week um can enhance hippocample function. The part of the brain that's very involved in declarative memory. Um and that part of the brain, you know, having turned 50 recently tends to decline by about one 2% a year in terms of volume.

00:17So this is kind of physical shrinkage of the brain. But in the walking group, the group that was randomly assigned to walk three, four times a week for 40 minutes, compared to a stretching group who's still engaging in exercise but not cardiovascular exercise, the walking group, their, you know, hippocampus actually increased in volume by 1%.

00:35So you're changing the the brain, but you're also changing the behavior. Their memory was much better a year later. So I think, you know, if you saw a doctor and said, you know, I'm having some memory problems. What can I do? most people are looking for a pill or you know sometimes it's eat this or do that but I think physical exercise can be so important uh and it probably the mechanism we don't know exactly but it probably trickles down to things like improvements in sleep as well you know if you're getting exercise maybe earlier in the day you're going to

01:07have better mood you're going to sleep better we know a lot of memory formation happens when you're sleeping uh we know as we get older our sleep quality tends to decline even if our quantity tends to increase. So I think just knowing that there are some things we can do and I'm using physical exercise as the example and it doesn't have to be you know the extreme version um walking, dancing.

01:27Um a lot of people you know enjoy being outside. Uh that can be incredibly important to offset some of the things we do know can can lead to dementia. Was the walking vigorous? you know, in this group, I think it's really 30 to 40 minutes. And there's nothing special.

01:47It's certainly about walking, but it's something where you can randomly assign people to either walk or engage in stretching. So, if you're biking, if you're swimming, if you're dancing, any of these things can be beneficial, but here it's, you know, you can randomly assign people to walk and and it should be at a rate where you're, you know, there's research showing that the people who walk slightly faster actually live longer.

02:05Um, so, you know, you're not sure exactly causality there. Could certainly be that. and and a lot of this research, it's tough to do aging research because it's hard to randomly assign people to to certain conditions,

Balance & Fall Prevention

02:17but I think as a psychologist, knowing that you have a little bit of control over the process is important. And I think, you know, most people when they talk about aging, they're so worried about dementia and, you know, Alzheimer's disease as a specific form, but balance is even more important, I think.

02:33And most people aren't even aware of their balance. Mhm. So, one in four people over the age of 65 will experience a fall and that fall can be very detrimental. You can break your hip, your collar bone often, you know, you're getting up at night more frequently.

02:48You trip over a carpet or a rug and, you know, if you're in bed recovering from these falls, you're not walking. You know, your hippocampus is shrinking. If you ask people, "How's how's your balance?" Most people are like, "Well, it's fine.

03:00I I don't haven't had a fall." But there's a very simple test. We could do it now if you wanted where you just stand up and see if you can balance on one leg for at least 10 seconds. And I have, you know, when I do presentations, I do this ideally 30, 40 minutes into the presentation.

03:15We shouldn't be sitting for so long. And most people do pretty well. It's a younger group and sometimes it's older adults I'm speaking to. And you can tell, you know, I'm like, "Make sure you have something you can hold on to." And you can tell that balance changes considerably with age.

03:27And then I say, "Okay, now try doing it with your eyes closed." And I actually usually don't do this with my older adult group because then you see the younger people start to tip. And you know, it's very we get a lot of cues from our visual environment for balance.

03:42The young the older people tip. Everyone, you'll see the younger people start to tip. That's why it's even more surprising. It's like a field sobriety test. It it very much is, but it's this again from this metacognitive standpoint where you think your balance is fine because you haven't had a fall, but you could be close to falling at any given point.

04:00And so, you know, the cerebellum, the almost very primitive part of the brain is involved in a lot of this. What's interesting with balance is it's very trainable. And so, you know, there's parts of balance that involve visual inner ear, but if you engage in some training, and it can be as simple as standing on one leg or doing yoga or taichi, you can improve your balance considerably within a month or two.

04:19And so, I think when I talk to older adults who, you know, sometimes are even middle-aged worried about their memory, I think balance is often overlooked and it's something that's trainable. Um, so I've started to do it a little bit and I've noticed changes in my balance.

04:35Sometimes good. I also notice I don't sleep well. my balance isn't as good. Um, and I think that's probably the most important thing to be on the lookout for because, you know, these things are related. If you if you lose your balance and you have a fall, you're not going to be engaging in physical exercise.

04:47Your memor is going to decline. Yeah, the old skiers and the uh old surfers look to be in pretty awesome shape. Um, there are million compounds there. The sunlight, the social connection, the water, the cold, the, you know, I mean, there are a bunch of things.

05:05Um, obviously it's not just the skiing or the surfing, but there are certain sports where you look at the people and you say, "Okay, they're not the biggest and strongest, nor are they the ones with the most endurance, but on balance, they seem strong.

05:18Their posture looks good."

Breathing Habits of Super Agers

05:22Yeah. Um, they seem relatively happy. Who knows, right? I'm intrigued by the fact that I look at a lot of these videos of of uh super aers and athletes in their 70s, 80s, 90s who are doing remarkably well. It's very rare to see a video of athletes or non-athletes past 80 where they're breathing through their nose with their mouth shut.

05:46Almost always you see, [panting and sighs] now I'm not saying it's causal, but there does seem to be a shift in the way that people breathe as they get older. just look at some of the um I forget his name now. He's a television um personality uh who's been around a long he's in his hundreds and he's been on YouTube and the and news programs recently.

06:06But at rest, it's like a mouth open breathing pattern. You kind of wonder whether or not they're getting enough oxygen to their brain. And I I do think that the shift in how we breathe, spontaneous movement, these things all go together. Um and I do think each component part needs to be looked at individually.

06:23So, okay. So, it's the movement, it's the exercise, the novelty, the social connection, but ultimately there's a lot of other things going on. Like, we know older people just don't they don't move spontaneously very much. We had Twilight Tharp in here, the you know, world famous choreographer, and she's in her somewhere in her 80s, you know, she can deadlift um twice her body weight, works out at 5:00 a.m.

06:45every morning for two hours. Wow. She boxed for a while. Yeah. Um but actual boxing cuz she's Twilight, right? She's she's a really uh she's got a lot of spirit, but she doesn't sit like I'm sitting like kind of lazy back. She's she's fully active and she's she's moving and she's nasal breathing when unless she's speaking like she's she's her nervous system is turned on.

07:07I notice that and I go, God willing, I'll be I'll be like that. But I notic with each passing year, I take a few more opportunities to lean against things as opposed to standing up, not leaning against them, or starting to resemble the bulldogs I've owned.

07:23There's opportunity to lie down, they lie down. If there's opportunity, you know, sleep. And I don't know that that's good. Maybe

Importance of Brain Oxygenation

07:30we need to nudge ourselves to be a little more active than we're comfortable. I think the insight is so important to be like, I notice I'm doing more of this or I'm looking a lot like this and I'm surprised. So things starting like posture or even breathing.

07:43And I think you know I'm not an expert in this area but just getting more oxygen to the brain is so important. I think that's probably the mechanism be you know for physical exercise you're getting more oxygen to your brain which really as you get older it's harder to do that and so exercise might be kind of the mechanism um that does that and maybe with the you know advances we're going to find other ways to do that.

08:02Uh but I think that insight is is really important and it's also you know we have age-based stereotypes of what happens like oh as you get older you know let's say you know my knee hurts and some people are like oh well you're just getting older well my other knee is the same age and it feels fine [laughter] so something's going on maybe there's some [clears throat] trauma there's something but it does give you this feeling like hey there's something I can do or maybe you know I'm a firm believer like in physical therapy like a lot of the exercises we do, you know, if you

08:36keep doing the same thing, that's great. But then you lose a lot of the other, you know, muscle mass and, you know, I think exercise, even walking, people will say it's really like a controlled form of losing your balance and regaining it and losing your balance and regaining it.

08:50And so you add that into hiking, which is has unpredictable surfaces. You know, all these muscles that are, you know, you're not using too often now have to be engaged. And so I think I think that coming back to like challenging yourself can be very important.

09:02putting yourself in uncomfortable positions. I mean, it's great to be on this podcast, but there's a time where I'm like, I'm not sure I want to do this, right? Like, you know, how do you get that feeling that way now? No, now I feel fine. But I think as we put ourselves in these uncomfortable positions and I remember, you know, when I first started teaching, you're like, gosh, 300 people, you know, is this this is an uncomfortable situation.

09:24And one of my mentors said, you know what, there's only one thing you need to do, and that's breathe. because you start to forget that, you know, that is the most primitive thing to get oxygen to your brain that then you can do what you probably can do quite well.

09:41And that's a a psychological oversight where we just kind of start, I don't know if it's just mouth breathing, but as we get older, you know, or there's more stress, we stop being aware of, you know, the things that can really help us. [music]