Science Friday - Your ‘Biological Age’ Could Be Different Than How Old You Are

Episode Date: May 30, 2024

Aging often looks very different on different people. There are some 70-year-olds that exercise regularly, have no trouble going for a walk around the block, and remain mentally sharp. Others really struggle at 70, and aren’t able to maintain a quality of life they’ve had in the past.There’s a growing field of medicine dedicated to better understanding how we age. And this field is looking less at the number on one’s birth certificate than you might expect. Dr. Aditi Gurkar, assistant professor of medicine at the University of Pittsburgh’s Aging Institute, is one of the researchers working to better understand why two different people may age very differently.Earlier this year, Dr. Gurkar and her team published a study that identified certain metabolites that seem to be reliable markers to index biological age. Dr. Gurkar joins Ira to talk about this study and the implications of better understanding a person’s biological age.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Could we be looking at age the wrong way? No two people age the same. And so biological age is what we think could capture health. It's Thursday, May 30th, and you're listening to Science Friday. I'm SciFri producer D. Peter Schmidt. We've all seen how some people seem to age more rapidly than others, even if they're at the same chronological age. So why is that?

Well, there's been a growing field of medicine dedicated to better understanding how we age. Here's Ira with a researcher who's trying to. find out more. Joining me now to talk about this is my guest, Dr. Adity Gerka, assistant professor of geriatric medicine at the University of Pittsburgh School of Medicine in Pittsburgh, PA. Welcome to Science Friday. Thank you so much for having me on the show, Ira. It's nice to have you. Now, I understand that you got into this topic of biological aging by watching your grandparents age. Is that right? You know, in India, we grew up in like sort of a joint family. So my grandparents actually stayed, home with us, which was great. I loved having my grandparents around. But as they were getting older,

it was very easy to tell that my grandfather, who aged, you know, very gracefully and naturally, did almost everything functionally till the end of life. You know, did my homework with me, told me grandpa jokes, basically. And on the other hand, my grandmother, you know, her last 15 years of her life. She could really not make it out of bed. She had dementia. Really could not even remember who I was. So at a very young age, I started wondering why, you know, two people in the same household, but seemed to age very differently. And that's kind of what captured my interest very early on. Well, is there is there a common definition of what aging or getting old is? That's the million dollar question, I guess. Right. We all.

all look at clonological age, which serves as a conventional marker, of course. That's the age that we have on our license and on our passports. However, just like you captured it in your introduction, no two people age the same. And so biological age is what we think could capture health. And so how healthy we are, how much wear and tear our bodies have gone through, basically telling us about how we feel. And it does so by capturing the interplay of multiple factors including our genetics, our environment, what did we eat last night? Or did we even get some exercise during the day? So biological aging is sort of like a quality of life thing. Correct. Correct. That much more difficult to measure. Yeah. And it's not something that you can

determine by just looking at a person. Unfortunately not. Maybe we can when a person's 70, 75 maybe, right? But the goal would be to capture biological age very early on so that we can predict whether one's going to be a healthy ager or a rapid ageer so that we can take the right steps to change that. Now, you recently made a breakthrough in biological markers to determine aging. Tell us what you found there. Well, thank you, first of all, for calling it a breakthrough. As a scientist, I'm always, you know, looking at my work and I think there's so much to do, right? Right.

But, yes, we are really excited about this new study that we did. Some of us in the field, including our lab, but many others, had identified that as we age, we all accumulate certain cells, disregulated cells in our body, that in popular. literature get called zombie cells. And in science, they call it senesin cells. So these cells accumulate in all of us and seem to be playing a major role in disease. Really? Yeah. And when I was a postdoc, seems like ages ago now, we had worked with multiple teams, including the Mayo Clinic and the Scripps Research Institute, to look for drugs that could eliminate such disson. dysfunctional cells, at least in animal models. And what was really exciting was when we could get rid of these zombie cells, at least the mice did much better. They aged much more healthy. And that was sort of like, oh, wow, can we start a process where we can delay biological aging?

Right. So in the study, what we did was we looked at markers of this senescence. But we also integrated it with another marker called metabolites. You know, our body releases unique small molecules, chemical fingerprints, if you will, all the time. And these are substrates, intermediates, and byproducts of our everyday metabolism. What's great about metabolites are they're circulating in all of us and can really tell us about how we feel. They tell us about our physical state, our functionality. So in this study, for the first time, we have integrated two very important things, metabolites, as well as markers of senescence together in order to capture biological age.

And so how do you judge what biological age is based on these markers? Great, great. So what we started out was with this cohort where we really looked at functional capacity, mostly by doing a walk test or a gate speed. The reason we decided to look at gate speed for our initial study was that the gate speed has been linked to hospital readmissions, linked to how we feel, and it really captures multiple things going on in our bodies, including pain, how we are feeling on a specific day, right? So all of these things together kind of go into gate speed and walking ability. So that's kind of what we captured in our first study was we called biological age as healthy ages who could walk for about six minutes without taking many rest and felt really good doing so.

There was a part of the cohort that could not walk for the six minutes continuously. and needed to take breaks. And so that's what we call rapid agers. Now, mind you, all of these people in this cohort were about the age of 65. And we kind of set off this chronological age setup or threshold to kind of really capture what's happening with age rather than comparing someone who's 25 with a 65-year-old. Right. So did you find more markers in a certain group of people? Tell me about that.

Yeah. So what was exciting was by looking at about 1,400 metabolites that are circulating in one's blood, we could come up with a marker of 25 metabolites that could distinguish between healthy ages and rapid ages. Now, what are these metabolites? Some of these are lipids. Some of these. Some of these, These are basically byproducts of plants, fruits, and vegetables that people eat. And together, these 25 metabolites could tell us who is a healthy ageer versus someone who could be an early or rapid ageer. So these sounds like sort of like aging risk factors. Well, in this case, that's actually a good point. And that's where we have now done some more work into looking at,

causal factors that could really drive biological aging. And we have come up with two things that we think are really exciting and we want to follow through. One is how well one's mitochondria functions. Mitochondria are these organelles in all of us, most popularly called the powerhouse of the cell. This is an organelle which is very important for metabolism, breaks down fatty acids, and gives us energy, basically. And so we find that healthy agers seem to have better mitochondria, more functional mitochondria, compared to rapid ages. So that's kind of exciting, and we think that rapid ages instead,

because they cannot use their mitochondria, seem to break down their fat in other places, such as another organelle called the endoplasmic reticulum or the ER. And here we get these byproducts that might end up being more toxic to health. So that's kind of the first thing we are following through. The other exciting part was, and this is more, I guess, you know, proof that my mom was right because my mom always told me to eat more vegetables. And one of the metabolites that we found in our study really comes from fruits and vegetables.

And this really correlates well with healthy ages. So, you know, I think, again, everybody, your moms were right. Please eat your fruits and vegetables. Well, it sounds like you were investigating the rapid aging people at 65. What about the normal, quote, unquote, aging people? Right. I mean, was there a difference there? And then I'm going to move on to the older people who are still, as I say, playing pickleball at 80.

Correct, correct. So in this cohort, we had 200 people that were, 100 of them were healthy ages, what you called normal, you know, aging. So these are the people who could play pickleball. They didn't need to rest for five minutes. They could walk fairly well. We had also captured many other things, including their memory scores, you know, how fast they can get in and get out of a chair, things like that. that. And these people did really well in these functional tests. So just like you said, people who can do great even in their 80s. Right. And then we compared them with the rapid ageers. So comparing these two is what gave us this index of healthy aging. I see. I see. So what about genetics? Because there are some people that, you know, like my mom lived to just about almost 100. Wow. Yes. Thank goodness.

And you come up with people who, you know, and we're having an aging population that's living a lot older for some people, aren't they? Absolutely. I mean, is there something useful you can take out of your study for that cohort? Absolutely. I mean, I think this is why we need to look at aging right now, you know. We are all surviving to much older ages than we did 40, 50 years ago. So our population demographics are changing completely. Now, does genetics play a role in biological aging?

Absolutely. There is no question about it. However, we think, and several studies have looked at this before, where they've compared even twins, right? So having very similar genetics and looked at how they age. and other factors can kind of control how one's aging. Even in these twin studies, their environment, their lifestyle choices, all of these made an impact on how they were aging, not just their genetics.

And so that's why we decided to look at metabolomics, because it can arise from capturing all of these factors, including genetics and lifestyle choices. So what are the implications of your findings? Are you talking about a possible test you can take at the doctor's office and look at your metabolites and say, oh, you're not eating enough vegetables or something like that? Yeah, I mean, the hope is that, you know, we are at very early stages in our study. What I'm really looking for in the future is, yes, when we do our annual exam, can we just

do a simple blood test? and that can tell us, although our chronological age is 40, like I am, but my biological age is only 30, or whether you're heading in the opposite way. And by catching your risk to be an early ageer, you know, we can perhaps personalize these interventions. Maybe someone has a lot more of these senescent cells. And so maybe there's an intervention of giving. senolytics or xenotherapeutics, the small molecules that can eliminate senescent cells, right?

Oh, I see. Now, on the other hand, some medical tests are based on how old you are. For example, a colonoscopies for cancer are not prescribed for people 75 or older, right? Because the risk outweighs the benefits. But if your biological age is, let's say, 65, and though your chronology is 75, shouldn't you still be getting those tests? Correct. Exactly. I mean, that's the thing is we know that, and especially now, I'm sure you've realized this as well. In the last few years, a lot of people in the middle age also have started becoming susceptible to other cancers, right? Yes, yes, absolutely.

And so we will have to change policies on when we have to start testing probably soon. And for something like that, we kind of need to dig deeper into what one's biological age is. So when might we see your test, your panel, so to speak, be available to doctors to use? Great question. As a scientist, I'm always very careful about, you know, making sure that our test is going to be sensitive. It's really going to pick up biological aging. And it's reliable and comfortable. right? Saying that, I think there are two main things we need to do. One is hopefully do a study where we can look at already known interventions for aging. For example, exercise. It's the best known intervention, at least that we have currently. So we are hoping that we can look at a cohort where before and after

exercise, do we see any changes in their biological age based on our metabolites? And then the second thing we need to do is figure out how early on can we tell a person is biologically aging. Is it in their 30s? Is it in their 50s? Or really, we have to wait until their 70s, right? And then it doesn't really serve a purpose or maybe much of a purpose. Right. So I think those two things are important questions to address. And we are really working towards both of these currently. And if we can get that to go, then I think I'm really looking forward to having this test a few years from now. So what you're saying is it's very important to determine your biological age, possibly even early in life, and then keep up with it, keep determining it as you get older because it's got a great impact. Absolutely. Absolutely. Because I think what we are doing in medicine now,

is only taking care of the symptoms. Once we have a disease, that's what we are treating. But if we can think of aging as the underlying factor that drives all of these diseases, and if we can really intervene early on in life, then the hope is we don't have to treat one disease at a time. We can just have a healthier life for a longer period of time. A lot of what you said is really interesting and makes a lot of sense. I want to thank you for taking time to be with us today. Thank you so much for having me again, Ira. Dr. Adity Gerka, assistant professor of geriatric medicine

at the University of Pittsburgh School of Medicine in Pittsburgh, Pennsylvania. And that's all the time we have for today. Lots of folks help make the show happen, including Kathleen Davis. Diana Plasker. Beth Rami. Danielle Johnson. Tomorrow we'll be rounding up the top news and science this week. I'm Cyfry producer D. Peter Schmidt. See you then.