Why Do Some People Live to 100—and How?

Thomas Perls, director of BU’s New England Centenarian Study, explains how and why some people live to 100 years old. While genetics plays a huge role in whether someone becomes a centenarian (or supercentenarian), Perls says we can still do four things to increase our chances of living longer. 

Find Perls’ Life Expectancy calculator here. 

Learn more about the New England Centenarian Study (NECS) here. The study is funded by the National Institute on Aging, the William M. Wood Foundation, and the Martin and Paulette Samowitz Family Foundation. 

Have a question or topic idea for a future episode? Send an email to today@bu.edu. Bonus points if you attach a voice memo with your question.

Transcript

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You can also find all this information in the show notes. Now on to the show. 

This is Question of the Week from BU Today. 

Today about one in every 5,000 people in the United States is a centenarian, or someone who is 100 or more years old; about 85 percent of them are women.

And while the odds aren't great that we'll all make it that far, the Census Bureau predicts that in about 40 years, the number of people who live to 100 could be six times as high. 

So, why do some people live to 100, and how? 

To learn more about it, in this episode BU Today executive editor Doug Most, talks to Thomas Perls, a BU School of Medicine professor of geriatrics and director of BU's New England Centenarian Study, the largest study of its kind in the world.

Thanks to the internet, we also discovered that Dr. Perls has created this life expectancy calculator based on his research. So we had Doug get an estimate. We figured that he'd want to discuss his results with Dr. Perls.

Doug Most: Tom Perls, thanks for joining our podcast today.

We're going to talk about living to 100, we're going to talk about whether I want to live to 100. What are you seeing out there right now in terms of how people are making adjustments or changes to their lifestyles? And I'm curious if you're noticing any trends or patterns in how people are living and perhaps setting themselves up to grow and live longer lives.

Thomas Perls: First of all, thanks very much for having me. Average life expectancy in the United States is not so great compared to other countries. In the United States average life expectancy is about 77 years or so. In other countries, it's as high as 82 years. And part of it, I'm afraid to say, is we are very much a country of haves and have nots.

And life expectancy is highly correlated with socioeconomic status, years of education, and access to good health care. For sure, there's a big chunk of our population that has all those things and there's also many who do not, and it's the many who do not that bring that average down.

And then there's a segment of the population that we'll talk about, where many of those things don't seem to matter in terms of getting to really, really old age, which is pretty interesting. But another thing is, we still have many people in this country who smoke. In a place like Hong Kong, where advertising is practically nonexistent for tobacco, where there's very, very strict rules about where one can smoke and a lot of education about the problems with smoking, the rates of smoking are very, very low.

And that probably plays a very big role in why their life expectancy is so high, at about almost 83 years.

Most: Can you talk about this number 100 and how that became a magic number? And do we want people living to 100? When people get that old, is there a question about the strain on the health-care system and how those people are cared for, and I'm curious if that's something that the study looks at?

Perls: We chose the number 100 and centenarians in part as a hook, and to describe, I think, pretty well, the people that we study. We wanted to study a group that was very rare, and set itself apart from others in terms of how they age. And really, what that boils down to is choosing that segment of the population that is about the one percentile of the oldest group in the population.

That would be women age 102 and men age 99, almost 100. So centenarians describes them pretty well. As far as why would you want to live to 100 if you wanted to—that was a really important question for us at the beginning of the study, which goes—I'm afraid to say—all the way back to about 1995 when I was a fellow in geriatrics at Harvard.

And back then, in my training, as a medical student, as a resident, the people that were the sickest it seemed were our oldest patients. And the ones that we worried about the most in terms of mortality, the idea of the older you get, the sicker you get, was very, very common among the lay public and even the medical community.

And so, if you thought the older you get, the sicker you get, then one would expect that everybody age 100 and older would have a myriad of age-related diseases and be on death's doorstep. The first few centenarians I got to meet as a geriatrics fellow did not fit that bill at all—they were among my healthiest patients actually.

One lady I remember, Celia, she was 102 and she was never around for me to go visit her at this independent living community. I thought maybe she was out seeing her doctors or something. But no, she was out playing piano at all kinds of gigs and really complex Chopin.

I mean, she was really one of the reasons for an epiphany, which was: Well, if she was all that sick, how would she have gotten to this age? And that these individuals must have aged very slowly and had very little in the way of aging-related diseases. And from there on, we've studied more than 2,000 centenarians.

Most: So, I want to know Celia's secret. What did Celia have that perhaps the rest of us wish we had? Is it genetics? Is it certain habits or her lifestyle that really helped her get to this age in such strong condition? How do I replicate what Celia got?

Perls: One of the things we've learned is that these individuals have a long history of aging very, very slowly. And they do delay any kind of disability towards the very end of their lives. Some of them have aging-related diseases, but they are highly resilient. And if they do have any aging-related disease, like cardiovascular disease or stroke, even diabetes, or some kinds of cancers, I would say those don't cause a problem for them.

They get to on average about age 94 and 95 without any disability, whereas other people either die of these diseases or they have long periods of disability before they die. And then, there's a group who get to even older ages, 104, 105, who not only greatly delayed disability, but also age-related diseases.

Our crème de la crème folks are those who are 110 and older, what we call super centenarians. They are truly amazing in terms of, on average, being disability-free and living independently at the average age of—are you ready?—105.

Now that delay in disability, and then to some degree delay in aging-related diseases, especially something like Alzheimer's disease, led to us turning this notion of the older you get, the sicker you get on its head. And coming up with this idea, the older you get, the healthier you've been. 

And to address your question of how do you get there, I would say most of us, really on average, should be able to get pretty close, based upon our health behaviors, to an average of about age 90.

That's a lot, that's 30 years beyond the age of 60, okay? That means you have maybe 40 years ahead of you if you do things right. Things like managing your stress really well. Eating right. And what I mean by eating right is have a diet that is conducive to what for you as a healthy weight.

And then to some degree, I would say also avoiding meat, or removing as much meat out of your diet as possible, maybe having it once a week or something like that. Certainly not smoking, that's a biggie. Regular exercise. I think certainly exercising every day is important. Mixing it up, not just doing aerobic exercise, but also strength training gets even more important as we get older, [because] it's especially important that we maintain muscle.

Muscle has all kinds of benefits for people as they get older. And if I'm asking too much, even just three times a week, it's a heck of a lot better than none at all. Last, I would say having the right genes and picking your parents or perhaps even your grandparents just right.

Now, how do we know doing everything right gets people to 90? And it isn't so much from our New England Centenarian Study, but rather from the Seventh Day Adventist Health Study, which is a study of Seventh Day Adventists who have a religion that really believes that God has given us this wonderful body, and it would be a sin to squander that gift.

And so we need to take really good care of ourselves. Through that belief, they've developed really common sense guidelines of what you should be doing, and those are basically the things I said. They tend to be vegetarian, they don't smoke, they don't drink alcohol, and maybe a little bit of alcohol is okay.

They regularly exercise. When they do eat, they tend to eat in moderation, so obesity tends to be relatively uncommon in this group. And they spend a lot of time with family and religion, which may help them manage their stress better. And lo and behold, average age in this group—even though it's a very mixed group in terms of race, and ethnicity, and geographic location, even socioeconomic status—they, on average, get to 86 if you're a man and 89, almost 90, if you're a woman.

Most: Do more women tend to live longer, or does that not factor in?

Perls: In terms of sex, women definitely win the longevity marathon by leaps and bounds. Only about 15 percent of centenarians are men, and the other 85 percent are women. Women age more slowly than men, they markedly delay things like cardiovascular disease and stroke compared to men.

Men tend to get those things in their 70s, and women tend to get those things in their 80s. And then there's this subgroup that obviously goes on to much older age.

Most: What is the trend right now? Are more people living longer? Are fewer people living longer? Which direction are we headed in?

Perls: We just got through COVID; that was a huge hit to average life expectancy, where we've lost a million people due to COVID in the United States, probably the highest rate per capita in the world. Aside from that hit, I think the United States' average life expectancy is getting better in great part because of the decline in smoking.

There are still areas where we can have a great deal of improvement, particularly in disadvantaged communities. And one of those areas is much better screening and treatment of high blood pressure. In terms of the number of centenarians, that number has actually grown a great deal even since we started the study.

In the 1990s, about one per 10,000 in the population was a centenarian. Now, it's doubled to one per 5,000. Back in the early 1900s, average life expectancy was only about 50. And much of that was because we lost so many people in infancy. A lot of children were dying during birth, they were dying because of infectious diseases, dirty water supplies, poor socioeconomic conditions.

So families could count on losing about a quarter of their children because of these problems. Then with clean water supply, years of education on average going up from 8 years to 12 years, much better socioeconomic conditions, and then later things like vaccines, a quarter more of the population was able to age.

And so, many more people were going on into adulthood. You combine that with improvements in health care and socioeconomic conditions for people in middle age, and you get this combined effect of many more people who would have otherwise died having the opportunity to go on to be 100.

And so that's why we've seen this doubling. But we're starting to hit a plateau, I think. With all those improvements, maybe the prevalence of centenarians will continue to increase a bit from one per 5,000 to, who knows, maybe one per 3,000 or something like that—that's to get to 100, 101.

Getting much beyond 102 or so becomes so strongly genetic that beyond doing these really good health behaviors that might get you at least to 90, genetic influence—again, picking your parents or grandparents really well—becomes really important. They say that getting to about age 90, 30 percent of that is going to be genetic, and 70 percent is going to be your health-related behaviors.

By the time you look at getting to 110, it's the opposite. It's likely 70 percent is genetic, and 30 percent is these differences in our behaviors.

Most: So I took the brief study that you have available—

Perls: So that's the livingto100.com life expectancy calculator.

Most: I consider myself a pretty healthy person. I don't eat a lot of meat. I jog three, four days a week, I do have stress in my life, but that's probably just because I have two teenagers. So I think that I was sort of hopeful that I would have a pretty good number, and it spit back at me that 88 was my magic number.

[LAUGHS]

Perls: Did the calculator give you a little bit of feedback about where you had taken some hits?

Most: There is some genetic history in my family. So my father has a history of heart disease, but he's still alive today, and 85, and actually pretty healthy.

So I think it said stress is something that I could try to work on. And it mentioned the genetics. Those are two factors that are pretty hard to control for me—[I] can't get rid of my teenagers and can't get rid of my genes. [Laughs]

Perls: Now, don't keep saying that about your wonderful children, who I am sure you absolutely love and adore.

Most: [Laughs]

Perls: Yes, and I guess I would just say about stress, stress is not always bad. It's not the amount of stress that matters, it's how you manage it that is key. In fact, some people thrive on stress in terms of it being motivating. Doing some things that are driven by stress can be very, very rewarding.

You usually know what it takes to decrease the things that stress makes you feel in a negative way. For me, that is regular exercise; for others, it may be meditation, or prayer, or yoga. And it's a matter of you doing the things that you know work for you, and taking the time to do that.

The thing about genes and whether people should be getting genetic tests or what have you, nobody should be doing that for now. All you have to do—and I apologize to people who are adopted and don't know their family histories—really is just look at your own family history. We know that longevity runs in families and remember that it's not just genes that run in families, behaviors run in families too, including things like not smoking and years of education, socioeconomic status, things like that.

But just look at the family history. You fortunately know that there was some cardiovascular disease with your dad. Well, that makes it all the more important for you to see your doctor to check your blood pressure, check your cholesterol, and any other cardiovascular risk factors and minimize those.

And then you're going to nip that in the bud, because fortunately, this day and age we have a lot of things in the toolbox to deal with cardiovascular disease that your dad may have not even had access to at a substantially younger age. The fact that you did not claim some longevity in your family probably made a difference between whether you got to 100 versus more around age 90.

And then maybe there was a little something else that you're just not admitting to us about because you're too embarrassed. 

Most: [Laughs] 

Perls: But so I would say that's a really important thing that all of us need to do is to take stock of family history. If there's colon cancer history in your family, you shouldn't start getting screened at age 50. You probably should start getting screened at age 35 or 40. 

Breast cancer [and] other forms of cancer have a strong familial component. And don't just shrug that off, that's a really important clue for your own life expectancy and health.

Most: What is next for the study? Where’s your focus? What are some of the things you hope to learn in the coming years?

Perls: We just got a couple of pretty large grants from the National Institute on Aging that are pretty interested in generating and actually sharing with investigators around the world a lot more molecular data that is from blood samples and actually also stool samples to produce a lot more data.

Because this is a pretty unique population, there aren't many studies like us, but they hold really important secrets. It's not a matter of lacking genetic variants and other biological markers associated with disease. They have many of the same things as just the usual population. What they have that is different is protective factors, things that actively protect you from the processes of aging and aging-related diseases.

And we want to discover those protective factors, believing that we may be able to translate those eventually into therapeutics and screening strategies that could help a lot more people not get to 100, but help them age better. And hopefully, start doing things like markedly delaying or even escaping a disease like Alzheimer's disease.

As I said, we're getting stool samples from our participants, so that we can look at the microbiome, looking at all the different bacterial populations they have. There's a really important connection between the bacteria in our gut and things like whether or not we get Alzheimer's disease and cardiovascular disease.

These bacteria produce all kinds of important substances that get into our blood streams, and we in part produce things that are important for the bacteria. It's a really important symbiotic relationship and when things go awry, that can also lead to some aging-related diseases, and that's becoming a very important topic.

We do things like network analyses, [and] can do some very complex analyses looking at the interaction of these different data to come up with what we call signatures, or fingerprints. And that can then be translated into understanding biological mechanisms or the underpinnings of this longevity. Again, it won't just be us—the National Institute on Aging is expecting us to share these data on a web portal that is accessible to investigators around the world to hopefully greatly accelerate these discoveries.

Most: Tom Perls, the director of the New England Centenarian Study, I really appreciate you joining our podcast today, and we look forward to hearing more from you and from the study in the future.

Perls: Thank you so much for having me.

 Ferrante: Thanks to Dr. Perls for joining us on this episode of Question of the Week.

To learn more about the New England Centenarian Study, be sure to check out the links in the show notes. If you want to figure out your own life expectancy, you can find the calculator at livingto100.com (that's living to the number one hundred.com.) The calculator takes about 10 minutes and along with the results, it also gives you some suggestions on how to add years to your life.

This episode was hosted by BU Today executive editor Doug Most, engineered by Andy Hallock, and produced by me, Dana Ferrante. Thanks for listening and see you in two weeks.