Personality Type and Cognitive Resilience

December 12, 2022

In this episode we discuss what’s known about the association between personality type and cognitive function. Further, the idea of resilience—or what protects the cognition of individuals with a high level of neuropathology associated with cognitive decline—might have important implications for dementia prevention. Our guests are Dr. Eileen Graham and Dr. Dan Mroczek. Drs. Graham and Mroczek are both faculty at Northwestern University with interests in how personality factors influence physical and cognitive health over the life course.

Transcript

Donovan Maust:

During the neuropathology portion of second year medical school classes across the country, pretty much everyone learns about this Alzheimer guy and a patient of his with symptoms, including short term memory loss. After the patient's death and autopsy, he discovered plaques and tangles in the brain tissue. Which in my medical student mind turned into the idea that plaques and tangles always equal dementia.

Of course I knew there are other types of neuropathology out there, but the bottom line seemed like once you get these misfolding or misaggregating proteins in the brain, you develop dementia. End of story. So imagine my surprise during fellowship to have a lecture where I learned that in fact neuropathology actually explains relatively little, or at least only part of the range of cognition that adults demonstrate. In other words, there are some people with relatively few plaques and tangles who have significantly impaired cognition while others have lots of these plaques and tangles, but are cognitively normal.

Sadly, I was too far along in my training to become a neuropathologist at that point, but it was fascinating to learn about this interplay between neuropathology and cognition. And it seems like these issues have pretty significant implications for dementia prevention or treatment. Today we're fortunate to welcome some guests to help us explore this.

Matt Davis:

I'm Matt Davis.

Donovan Maust:

And I'm Donovan Maust.

Matt Davis:

You're listening to Minding Memory, a podcast devoted to exploring research on Alzheimer's disease and other related dementias.

Donovan Maust:

So our guests today are Dr. Eileen Graham and Dr. Dan Mroczek. Doctors Graham and Mroczek are both faculty at Northwestern University with interest in how personality factors influence physical and cognitive health over the life course. Dr. Graham is the first author of the paper we'll discuss today. And Dr. Mroczek is the senior author. Thank you both so much for joining us.

Dan Mroczek:

Thank you.

Eileen Graham:

Thank you for having us.

Donovan Maust:

So I wanted to begin, in the background of your article there's this statement that one study showed that only 40% of cognitive decline is explained by neuropathologies. So just a couple questions related to that statement. First, little detail oriented. Can you actually explain how is neuropathology actually quantified? It's not like you weigh the plaques and tangles. So where do you come up with that measure?

Eileen Graham:

So in the studies or the data sets that we use to analyze the data for this article, one of the elements of consent when people joined the study was that they consented to being autopsied after they died. So after the study tracked these individuals over the course of the full study period, they died of whatever natural causes they died of. And then the study then autopsied their brains, allowing the researchers or the clinicians as part of the research project to actually gather the neuropathologic data based on those autopsies.

Donovan Maust:

Is it like a stain that's being quantified?

Eileen Graham:

Yes, that is one of the ways that they did... One of the things that they measured as they were doing the autopsy was staining, was one of the techniques.

Dan Mroczek:

Yeah. They take coronal slices of the brain and then essentially do counts of different key dementia related neuropathologies. Such as tau proteins, amyloid plaques, Lewy bodies, things like that.

Eileen Graham:

But there were also, there were a number of other indicators that they collected in addition to the more traditional plaques and tangles. Like Dan mentioned TDP-43, but then they also gathered information on hippocampal sclerosis, micro infarcts, Lewy bodies, atherosclerosis, and arterial sclerosis.

Matt Davis:

So only 40% of cognitive decline being explained by neuropathology is kind of surprising. How should people sort of make sense of that?

Dan Mroczek:

That's a great question. It means that only a fraction of the kind of the clinical aspects of cognitive functioning decline are related to underlying neuropathology. You think there would be a one to one correspondence between... There's lots of neuropathology, there should be cognitive decline and clinical dementia. But it's not a one to one relationship.

There are people who are living with the disease. They have lots of neuropathology in their brain, but they're not showing the clinical syndromes of dementia or even substantial subclinical cognitive decline. It's that disparity, this discordance that is so interesting. And so there's lots of other things that are going on, obviously with that other 60%. What are the things that are accounting for this cognitive decline, other than neuropathology?

And that's one of the things that we explored in this paper. Personality is one of them, but there's others as well. We can get to that later in the podcast.

Eileen Graham:

Yeah. So as personality researchers, we are by nature... We study individual differences. So across everything that we study, we're interested in explaining variation on various outcomes. So the fact that 40% of cognitive decline can be explained by neuropathologies means a couple things to us. So we're usually, when we are saying something like that, we're speaking in fairly statistical terms in terms of a regression model. The amount of variation in neuropathology that can be explained by cognitive decline from a statistical modeling standpoint, 40% is actually quite a bit.

But that also leaves room for other factors to then explain the additional variation in neuropathology. And that's where personality comes in, at least from our interest standpoint.

Donovan Maust:

So that was a perfect segue to the next question. So the title of your paper is Associations Between Personality Traits and Cognitive Resilience in Older Adults. So for listeners, psychologist, or neuropsychologist, when they think about, or talk about personality, you'll hear these specific traits that are often referred to as the big five. Which are neuroticism, conscientiousness, openness, extroversion, and agreeableness.

So I'm wondering for our guests, if you could kind of run us through those big five and if you were talking to somebody at a dinner party and trying to explain what each one of them kind of capture? Could you talk us through those?

Eileen Graham:

We would love to.

Dan Mroczek:

So maybe I'll start with neuroticism. So again, first of all. Think of all the big five traits the way you would think of SAT scores. They're a continua. They are dimensions. The way you would think of SAT math ability or SAT verbal ability. They're kind of... Think of the 99th percentile going all the way through the 50th percentile down to the first percentile.

So neuroticism, think of the most anxious, fearful, stressed out person that you know. That person is probably... Well, you're a psychiatrist. So you probably know people who are perpetually experiencing negative emotion. Those are the individuals that are at the 90th, 95th percentile or higher. Again, imagine people who are in the middle ranges, 60th percentile, 50th, 40th, and so on. And then imagine the lower ends of that range. People at the 20th, 10th, 5th percentile. Those are people who are just kind of, from a dispositional perspective, just very cool, calm, collected. Don't get stressed out very much. Experiencing very, very low levels of negative affect. Even when there's a stressor present. That would be the dimension of neuroticism. Eileen, why don't you pick the next big five trait?

Eileen Graham:

All right. So thank you. So conscientiousness is describing a person's tendency towards efficiency, organization, motivation. People who score high on conscientiousness are typically very motivated and achievement oriented. They tend to be very planful and kind of thinking ahead and following through on tasks. Whereas somebody who's very low on conscientiousness might have a tendency towards impulsivity, have self-control issues. They tend to be less organized and put things off to the last minute.

And there's not necessarily a... So it's separate from neuroticism where there's not an emotional component to it. Whereas they're not anxious about the fact that they put things off to the last minute. It's just, "This is the choice that I've made. And now I have to live with these consequences of this." So also, like Dan said, these are all on a dimension. So everybody has all of these traits and they would score high or low or somewhere in the middle. So there's a distribution for all of these traits. So people kind of fall somewhere in the middle or off to the sides of the average.

Matt Davis:

I was going to ask if they were mutually exclusive, but it sounds like there's a lot of overlap.

Eileen Graham:

No, and I think that's one of the constant, I think uphill battles that we are constantly in as personality psychologists, is that we're always fighting with the ideas around personality inventories that really put people into bins. And that people do not fall into discrete categories as neatly as we would like.

If you say, "I'm an introvert, but sometimes I feel kind of extroverted. I like being social." That doesn't mean you're a bad introvert. It means that you fall on a continuum, not into a discrete category. So that's why we speak very specifically in terms of these traits that they are a continuum or a dimension and you can be high or low or somewhere in the middle.

Dan Mroczek:

Because Eileen just mentioned extroversion. And I guess I'll do that one next. So extroversion, introversion, same thing. It's a continuum. And by the way, you can flip these continua. It would be like, instead of SAT math ability, 99th percentile being high, and 1% being low. You can flip it. It's arbitrary. So just typically it's at the researchers' discretion that, "Well, we can put extraversion at the 99th percentile."

So imagine the person in your life that is the most gregarious, the most loving of social activity. The person that you know in your life who is really craving social activity. Really, really enjoys being around people. That person is probably pretty high on extraversion. They're probably at least above the 90th percentile or more. There's lots of people that you know who would be in the middle ranges, obviously. Maybe leaning to one side or the other. And then think of the shyest person that you know.

Think of the person that really would prefer to be kind of alone at home reading a book. That person is probably down at the lower end of that particular dimension, more towards the introverted end. Maybe around the 15th, 10th, 5th percentile on introversion, or on this particular dimension.

Eileen Graham:

So openness to experience is a trait that is most closely characterized by somebody who is very curious, very inventive, very willing to go out and explore the world. Not necessarily in a social way, but in more of an exploratory way. These people tend to be much more highly educated, and it's very closely associated with higher intelligence.

Dan Mroczek:

And finally agreeableness versus the other end. Sometimes it's called hostility or kind of lack of warmth or something like that. Or unkindness. It's this dimension that essentially gets at friendliness or warmth versus unfriendliness. People high in agreeableness are very kind, very nice people. There's a lot of empirical research indicating that people high in agreeableness are really good people to be married to.

And so they tend to have longer marriages and so on. And then at the other end of the spectrum you have people who are highly disagreeable. So think of like the most curmudgeonly person that you know in your life. That person is probably down at the lower end of that dimension. Not so warm. Not so nice. And so on. So that's what that dimension is.

Donovan Maust:

Are the big five a pretty kind of settled construct? Is there still bickering over whether or not it matters or are people on board, the big five matter?

Eileen Graham:

Scientists will always bicker.

Donovan Maust:

Right. Yeah.

Dan Mroczek:

There's agreement that it's a good coarse level. Dan McAdams, our colleague here at Northwestern has called it the psychology of the stranger. What are the five things you need to know about a stranger when you first meet somebody? Well, is this person kind of social. Extroversion. How is the person going to handle stress? Neuroticism. Is the person reliable? Conscientious. The psychology of the stranger. But you don't know a person really if you know just the big five. You might know the person's percentile score on the big five. That doesn't tell you very much about the person in a deep way. You don't know their loves, their desires, their motives, things like that. So personality does go a lot deeper. But the big five is... There's agreement that yeah, it's a decent coarse level of personality. Some people are getting into, "Well, is there a finer level of traits?" And then other people are getting into, well, completely other aspects of personality like narrative identity and things like that. So there's more to personality than just the big five, but there is agreement that it's... Yeah. For a basic model of personality, it's not too bad.

Matt Davis:

And how is it measured?

Dan Mroczek:

Typically self-reports, but there's some pretty good external informant reports where you might have friends or...

Eileen Graham:

A caregiver.

Dan Mroczek:

Yeah. Oh, yeah. A lot of caregiving research, caregivers, family members. In school settings, classmates. So there's an honored tradition of having external... Other reports. But I'd say probably most of the time it's self-reports.

Eileen Graham:

Yeah. And it's usually a series of items or statements that people have to rate the extent to which they agree that that statement describes them. Like, "I tend to be very organized." One being, highly disagree. Five being, highly agree. So for each of the traits, there's usually a handful of items. Sometimes upwards of 20, depending on the exact tool used to measure the big five. And there's several out there. So people rate how much they agree or how well that statement describes them or how well this adjective describes them. And then those are aggregated in some way to create a composite score of that trait.

Matt Davis:

Having a partner rate a person. That's kind of interesting. It's like, "I think I'm really agreeable." And they're like, "Well, I don't know about that."

Dan Mroczek:

There is actually some pretty cool research, mainly done by Simine Vazire who was at Washington St. Louis and later UC Davis on disparity between other reports and self-reports. And the one where you find actually the most is actually agreeableness. Most people say, "Oh, I'm a nice person." But a lot of other people are like, "Well, no. You're really not."

The one where self-reports are actually the best is actually neuroticism. People tend to know, they tend to know themselves when it comes to things like depression and anxiety. It's like, "Yeah, I'm feeling negative emotions right now. And I am the one feeling them. And so I can self-report on that. But other people are not able to do so." Other reports are also pretty good for extroversion as well. People can usually tell, "Yeah, yeah, you're an extrovert." So that's an interesting line of research.

Donovan Maust:

For your study you used two ongoing cohort studies in the Chicago area. I think we've talked about one, maybe both of them with previous guests. So the Religious Orders Study and the Rush Memory and Aging Project. At a very high level could you just explain to us what were your exposures and outcomes of interest? What were your hypotheses going in? And did you find what you expected to find or were you surprised by your findings at all?

Eileen Graham:

So the very basics of the study were, we used the data from the Religious Orders Study and the Rush Memory and Aging Project to answer our questions. Both of these data sets are based out of the Rush University Alzheimer's Disease Research Center. The Religious Orders Study started in the early '90s and the Memory and Aging Project started about 10 years later. And they were kind of meant to be paired with one another. So the design and the methodology is essentially the same. The key difference between the two is that Religious Orders Study is based solely on priests and nuns and other people in religious orders. Whereas the Rush Memory and Aging Project is strictly community dwelling, older adults in the Chicago area.

So when people signed up for the study or consented to being in the study, one of the first things they did was fill out a personality inventory and basically gave data, provided data on their big five personality traits at what we call baseline. And then over the course of the study among other things, there were many, many things studied or collected in these two studies. They provided cognitive data at every measurement occasion. Which occurred annually. And this was a pretty broad cognitive battery where they did working memory tasks, episodic memory tasks, speed of processing, executive functioning, among other things. To provide a pretty complete picture of what their cognitive function is at every wave of measurement, which is yearly.

So that gives us some very, very rich data on how their cognitive function is progressing throughout their older adulthood. And then as these individuals would die throughout the life of the study, then their brains were autopsied. So we have that neuropathologic data at the very end of their participation. So what we expected to find... We had a couple key hypotheses, mostly around neuroticism, conscientiousness and openness to experience. Those tend to be the three traits that are most consistently associated with various cognitive outcomes in the existing literature.

So for this particular study where we were creating an index of cognitive resilience, we expected to find those three traits to also be related. Mostly that openness and conscientiousness, people who score higher on those two traits, we expected them to have better or more cognitive resilience. And people higher in neuroticism, we expected them to have lower cognitive resilience or more cognitive vulnerability.

Donovan Maust:

And so to be clear, when you're saying cognitive resilience, you mean given the level of neuropathology they have, their cognitive function is better than you would've expected. Is that right?

Eileen Graham:

Yes, exactly. So what we did once we had this data, we took all of the neuropathological indicators of which there were many. And we regressed cognitive function onto those neuropathologic indicators. So in a regression model, that essentially means we have all of this variance in cognitive function. How well does neuropathology predict that? Or how much of the variance in cognition does neuropathology account for?

And whatever variance was not accounted for gets extracted as this residual. So that residual variance is whatever is left over. And that gives us an indication of basically the extent to which somebody has better or worse cognition given their amount of neuropathology. So that residual, we then extracted from the model and used that as our key outcome. So somebody with a higher score, which we named the residual cognitive resilience. Somebody with a higher resilience score has better than expected cognitive function, given the amount of neuropathology they had. And then somebody with a very low score has worse than expected cognitive function, given the amount of neuropathology.

Matt Davis:

That was really cool. And a great example of residuals. Using a residual for something other than just testing your model fit, right?

Eileen Graham:

Right. Exactly.

Dan Mroczek:

No, we should mention that the overall regression line was, as you would expect, it was negative. So on the X axis there's these various indicators of neuropathology [inaudible 00:22:57]. So as neuropathology goes up, as there's greater amounts of neuropathology, there was lower cognitive functioning. Whether it's less visible before death. Or the other version that Eileen mentioned. Using all of the yearly measurements.

And we did it two ways. In both you have this negative regression line, which is what you would expect. Greater neuropathology, lower cognitive functioning. But of course it's not perfect. There's all this scatter around the line. And the distances between every observed point and predicted point are these residuals. And we can harness those residuals to get at this very interesting concept of cognitive resilience.

Eileen Graham:

So similar work has been done, but using more discreet tools to measure this. So other studies have looked at kind of categorizing people. Somebody with high pathology and high cognition, low pathology, low cognition. And then the opposite. If you're low on one, high in the other. High on one, low in the other.

So those are like the concordant and discordant quadrants. And seeing if we can describe people in each of those quadrants. But using residuals is a very unique way of actually being able to keep that continuous information continuous and actually using all of that variance. And so it gives a much richer picture into these other factors that can predict it.

Matt Davis:

Is the basic underlying premise of this though, this idea of looking at personality types and cognitive resilience, is it based on the assumption that different personalities elicit different specific behaviors? And is that kind of the pathway of sort of causality you're imagining?

Eileen Graham:

Yes. So our general theoretical framework is that people with certain personality characteristics or higher levels of certain traits are more likely to either have the tools or go out and get the tools or do the things that are going to ultimately protect them. And that's what's then resulting in better or worse health outcomes later on in life. So it's kind of in a way inherently a mediation model, if you will.

But a lot of the work we do is just looking at these direct pathways. So how well can we predict health using personality? And then the next step is to look at how. So do certain personality traits or people with high levels of certain personality characteristics, more likely to engage in X behaviors that then predicts their health.

Dan Mroczek:

There's a whole line of research that we were pursuing prior to getting into this cognitive resilience work that Eileen and I were pursuing. And then, which I was pursuing before I came to Northwestern when I was at Purdue. That exactly did what you had just mentioned. Why is personality related to mortality risk? Actually, that's what I was really into at the time.

And it's definitely the case that when personalities were related to any kind of health outcome, whether it's some kind of dementia risk or cognitive resilience or mortality risk or any other kind of physical health outcome, it's typically through some kind of health behavior. Not always, but it's usually through some kind of health behavior.

Conscientiousness, for example. Say you're low in conscientiousness. You have impulse control, self-control issues. You're going to be much less likely to take good care of yourself. Keep doctor appointments. Adhere to your medications. Not exercise regularly, maybe engage in poor health behaviors. That over many years will accumulate and lead to a whole host of poor health outcomes down the road, including dementia risk, increased risk for other physical detrimental health outcomes.

And certainly increased mortality risk as well. But yeah, that's exactly where the pathway. And actually, Eileen has a great paper from 2017. It actually shows in multiple study showing the effect of smoking as a health behavior that kind of comes in between personality and mortality risk.

Donovan Maust:

In the discussion there is occasionally use of the phrase, healthy neuroticism. Is the idea there sort of you're neurotic, which you would think might reduce resilience, but if it's kind of channeled in a healthy, productive way, maybe it promotes resilience.

Eileen Graham:

Possibly.

Donovan Maust:

I sort of butchered that.

Matt Davis:

An oxymoron kind of.

Dan Mroczek:

That's the idea, but we been searching for evidence for the idea and it's been elusive.

Eileen Graham:

This is a line of research that we have been pursuing, and there are many ways that one could define healthy neuroticism. The way that we have defined it in the past is the interaction between conscientiousness and neuroticism. So essentially asking what if somebody is both high in conscientiousness and neuroticism? Do the negative effects of neuroticism overriding the positive effects of being conscientious? Or is it possible that somebody's high conscientiousness is kind of ameliorating the negative impacts of a person's neuroticism?

So we did this a couple years ago with this project we did, where we looked at that interaction across a range of health behaviors, health outcomes, and mortality. And we actually found that it seems most closely related to health behaviors, but that does not seem to extend to actual health outcomes or relate to mortality at all.

So like Dan said, it is a little bit elusive. There could be other ways of defining it that might be better able to capture the health benefits. But it does seem to be related to your likelihood of engaging in health behaviors. So when we're talking about this cognitive resilience project, we found it really interesting that the two traits that were related to cognitive resilience were conscientiousness and neuroticism, but separately.

So people who were higher in neuroticism tended to have lower cognitive resilience and people with higher conscientiousness tended to have higher cognitive resilience. So then the question that we would like to ask and probably will in a future project at some point is, if we interact the two, will we find that being high in both is better for cognitive resilience or worse?

Matt Davis:

When you say interact, you mean people that have both?

Eileen Graham:

Right. Exactly.

Dan Mroczek:

Yeah. The idea is, does the high anxiety of neuroticism kind of combined with the kind of motivational aspects of high conscientiousness. So say you see something on your skin and you say, "Oh, my God. Oh, my goodness. This scares me. I really need to get it checked out." And so it's both the anxiety, combination of the fear, the anxiety, "What is this thing?" Combined with the fact that you're high conscientious, and you're motivated to take action.

Dan Mroczek:

That both those things together get you to the doctor to get it checked out. And if it's nothing that's fine. But what if it is something? Then you've caught it really early? So that's kind of the idea underlying healthy neuroticism. It's an idea that was first postulated about 22 years ago by Howard Friedman at UC Riverside. He's retired now. But it's a great idea. We've struggled to come up with empirical proof for it.

Matt Davis:

This next question I have is probably a little bit too much in the weeds. But one of the cohorts that you said that you used was this Religious Orders Study, which is made up of priests and nuns. Right? Did you have any concerns about that group when you're looking at personality and cognitive resilience being different somehow in terms of their behaviors and how their personalities might not sort of manufacture different types of behavioral stuff?

Eileen Graham:

Absolutely. It is a very, very unique sample and that's part of why we paired it with the Memory and Aging Project. So we could see, in addition to the uniqueness of the priests and nuns when paired with the community dwelling older adults what kind of pattern do you see. From a statistical power standpoint, we're not really at a point where we can look very easily at the two samples separately because we need to wait for enough people to die to really model this in a way that is robust and convincing.

So currently the analyses have been done with the two together, but it would be really interesting to kind of run the same analysis on both samples separately. And then talk about the differences that we see. So is there something unique about being in a religious order that is either biasing the sample in a positive way, like is there an advantage to being in a religious order or is it disadvantageous? We don't know.

Dan Mroczek:

One thing about the Religious Orders Study is... So one of the other factors that is related to cognitive resilience is education. That's an obvious one. The more years of education you have, the more you are likely to kind of have this greater amount of resilience. That you can tolerate the neuropathology. Cognitively engaging careers are also another factors.

So this is known from other research. The thing about people, priest and nuns especially born of this era. They were all born... I think Eileen in the 1920s and 1930s, compared to their cohort mates, people born around those same decades, 1920s, 1930s. They all would've had bachelor's degrees and many of them would've had master's degrees. And so they were more educated than other people of that typical generation. And so they probably had higher levels of cognitive resilience, at least in a Religious Orders Study. The map people however, were probably more representative of the general population.

Donovan Maust:

I should ask this back when we were first asking you to explain the big five. But do these change over time or are they pretty much like a fixed characteristic?

Dan Mroczek:

We love this question.

Eileen Graham:

That's an empirical question and we love it.

Dan Mroczek:

But one we have an answer to. Because we've actually spent a lot of years of... So I want you to start out Eileen and then I can chime in at the end.

Eileen Graham:

Yeah. So one of our biggest papers that we put out recently was looking across I think 16 independent data sets that have been tracking people across the world of varying age ranges, the extent to which their big five personality traits change over time. And there is evidence for change, but it's a relatively small amount. Enough to be statistically significant. But in general, we do see patterns of change over time enough to be convincing that studies should be measuring this frequently throughout the life of their study.

Because changing personality could be as, if not more influential on a person's health later on. And that's particularly relevant to cognitive health because for some, even in the DSM, personality change can be considered a symptom of dementia if it's extreme enough. So actually tracking a person's personality change throughout their healthy or possibly prodromal years could be really useful information for understanding whether or not somebody is likely to develop severe cognitive dysfunction or dementia later on.

Donovan Maust:

And do all five change or is it kind of one or two in particular that are the movers?

Eileen Graham:

We see patterns for change in all of them. The most extreme being neuroticism, and then to a lesser extent, extroversion, conscientiousness. And then the weakest ones that we found were for agreeableness. But we're still unpacking why. We found that for some studies agreeableness went up on average. For some, it went down on average. But there also tends to be more measurement differences in the way people ask about agreeableness in the various studies. So we still need to disentangle whether that's a measurement thing or a true difference in change.

Dan Mroczek:

There are individual differences in personality change. So personality itself like depression, like anxiety, like math ability, like verbal ability, these personality traits are individual differences, variables. Well, personality change is also an individual differences variable. That is, some people change and some people change a lot and other people are stable. So in any study, if you do these growth curve models, these multilevel models, you will find some individuals who are... Some people are pretty stable over their lifespan.

After adolescence. There's a lot of change in the childhood and adolescent years. There's a lot of brain development going on. And so for each of the big five traits, there's a lot of change that's going on prior to the adulthood. But once you get to adulthood, some people display change, but other people display stability.

So there's individual differences in change. What Eileen says is correct. What predicts that change? That's been more elusive. There's some theories about social roles and taking on different social roles. That that might be related. That is, when you start a career, partner with someone, have children, that that might promote a conscientiousness, might lower neuroticism. There's some theories about that.

And there's some evidence to suggest that that might be the case. But in general, predictors of change are a little bit more elusive. But the general concept of individual differences in change. Some people are stable and some people are changing. That's something that's been shown by many studies across many countries.

Matt Davis:

I must say I am so relieved that we have empirical evidence that people, yes, can change. I suspect there might be an age threshold though where it's probably pretty unlikely.

Dan Mroczek:

It actually went against a lot of dogma back in the... When some of us back in the 1990s were first showing this to be true. It had become dogma that, "No, personality is stable for everybody. No one changes ever." And that was the 1980. When I was at University of Michigan as a postdoc in the early, mid 1990s, it had really become dogma that the personality does not change. But then by the late '90s, those of us who were starting to do the first growth curve models on... We were like, "Oh, wow. Yes. So some people are stable, but other people do show change."

Eileen Graham:

We run into trouble now when we're trying to analyze data from some of these long-term longitudinal studies, because many of them started back when the prevailing assumption was that personality is stable. Fortunately that has changed. That is not the dogma anymore, but many of these data sets, unfortunately only have personality measurements at that baseline assessment because they assumed it wasn't going to change. We only need to measure it once.

So in this project, unfortunately we can't study personality change of cognitive resilience because we only have a single measurement occasion.

Dan Mroczek:

Yeah. Yeah. The Rush studies are…I know, Eileen and I had a conversation with the director of the ADRC at Rush, David Bennett. Who's a good friend of ours. And, he was like, "Yeah. We were told back in the '90s that personality doesn't change. So you just measure it once."

Eileen Graham:

So if we could go back in our time machine and tell them all, "You have to keep measuring it."

Matt Davis:

Has anybody ever looked at partners of different combinations of personality? I mean, I could sort of imagine that different personalities could affect behavior. Right?

Dan Mroczek:

It's an emerging area. I can say, this is one area where we don't know a lot. There's a lot of interest. I mean, how do different personality traits interact with one another. Healthy neuroticism is the one... There was like, a whole theoretical paper came out. There was some tests. Looks like it... Maybe that one is not going to work out. Perhaps. But there are individuals around the country and around the world that are kind of interested in testing other combinations.

Dan Mroczek:

Like how do different traits interact with one another. Right now, there's nothing really clear or definitive. But I'd say give it 5 or 10 years. And I imagine there's going to be probably more papers than you have time to read. Because there is a lot of interest among many young researchers on trying try to answer these questions. It's a great question.

Donovan Maust:

Anything, any final burning questions, Matt?

Matt Davis:

I was just thinking, it was kind of funny this is a podcast on dementia and we focused on these personality things. Because I don't know, they're kind of new to us and I was thinking, I was like, too bad you can't find five more. And then it would be the big 10. Then we could really put our stamp on it.

Dan Mroczek:

I mean, some of these... I mean we focused on... We've been working on personality as a predictor of cognitive resilience, but like we said earlier, there's others that have looked at other predictors. And education and then kind of being in a cognitively engaged career. Those are two others where there's a fair amount of work. And so it's really kind of cool to think that a major health promoting variable is education.

Get educated and that will actually promote your health. It'll promote your cognitive health. It'll also promote your physical health. Because people who have high level of education tend to live longer, they tend to have better health. So it's kind of a, eat healthy, exercise regularly, take your medications as prescribed, and get as many years as education as possible. And you'll live a healthy life.

Donovan Maust:

So thank you all so much for your time and sharing your expertise with us. For now I think that that's all.

Dan Mroczek:

Thank you.

Eileen Graham:

That was really fun. Thank you guys so much for inviting us.

Matt Davis:

If you enjoyed our discussion today, please consider subscribing to our podcast. Other episodes can be found on Apple Podcasts, Spotify and SoundCloud, as well as directly from us at capra.med.umich.edu. Where a full transcript of this episode is also available. On our website you'll also find links to our seminar series and the data products we've created for dementia research. Music and engineering for this podcast was provided by Dan Langa. More information available at www.danlanga.com.

Minding Memory is part of the Michigan Medicine Podcast Network. Find more shows at uofmhealth.org/podcast. Support for this podcast comes from the National Institute on Aging at the National Institute of Health, as well as the Institute for Healthcare Policy and Innovation at the University of Michigan. The views expressed in this podcast do not necessarily represent the views of the NIH or the University of Michigan. Thanks for joining us. And we'll be back soon.

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