Coffee, Tea and Dementia

Preston: [00:00:00] So if you remember in the late nineties and early two thousands, people would say, Hey, turns out if you drink wine, you live longer. Maybe it has to do with the antioxidant benefits of grapes and blah, blah, blah. And there's all this explanation. And it turns out that this has now been debunked, and it's probably because rich people are more likely to drink wine and it was being rich all along.

Yep.

And welcome back to How to Be Patient. The podcast where we are. We 

Margaret: don't talk about death for a day. 

Preston: Yeah, no death. this is just no existential themes today, 

Margaret: guys, 

Preston: today coffee, change chat, and more than just my accent is actually the content of this episode, which is going to be coffee, tea intake, dementia risk, and cognitive function.

We, it's 

Margaret: a journal club episode. It's, you 

Preston: knew was coming. You're getting [00:01:00] jam right now.

So this, and this is hot off the press, not as hot as the coffee I had this morning, but this came out in early February and this is a, study done by the, Harvard School of Public Health. And very interesting content we have here. But before we go any farther with this study, 

Margaret: content being the journal article, 

Preston: you know, that's kind of what I was thinking.

As 

Margaret: you once said, 

Preston: it's 

Margaret: all content. As you once said, in our early like three episodes, you said, what are academics but content creators that. You didn't say this, but that don't get enough views. 

Preston: True. Yeah. 

Margaret: And everything's, 

Preston: they're, dry content creators is what they are. 

Margaret: I feel like we're like news for those of you who are listening, these 

Preston: less velocity edits and like zoom maybe that help them lens transitions.

So for those 

Margaret: of you who are listening and not watching, I feel like we're like news anchors today with the like and coming at you live outta Denver. [00:02:00] Coming at you Live outta Chan Public School of Health at Harvard in Boston. 

Preston: Try to gimme your best news anchor voice. 

Margaret: Oh, I can't do it on the spot. I get nervous.

Preston: Okay. 

Margaret: I get nervous. 

Preston: on the spot this afternoon looking at Margaret, who is attempting to give her news anchor voice, but pressures seem a bit high. 

Margaret: It's too high. This is why I don't talk to camera TikTok, dude, 

Preston: that I 

Margaret: can't do it. At first, I thought it was insecurity, and now it's just like I truly look at the camera and I'm like, I have nothing for you.

If you were like, talk to the camera for the next 10 minutes, I can talk to you. 'cause I'm pretending I'm just talking to you. Mm-hmm. And no one else is here. Gotcha. And I'm like, let me yell at Preston for an hour. But you were like yell at the camera. Can 

Preston: you, always 

Margaret: yell at 

Preston: me. 

Margaret: I know one. 

Preston: And now back to our mean stories.

So that was Margaret. Everyone moving on with today's icebreaker breaker. So the icebreaker is, what is your favorite way to consume caffeine? 

Margaret: I love a drip coffee. [00:03:00] For me personally, 

Preston: mic drop. Who, can say anything more than a drip coffee? 

Margaret: I love a drip coffee. I love, like I have like a Smeg coffee maker, so it's like pastel blue and pretty, and I love 

Preston: smeg.

Margaret: And then I, you can, I set it like many coffee makers in 2026. You can set it the night before. and so I'll like wake up in the morning and I have these like lights that can be turned on by like, on a schedule. And so my like lamp slowly starts to turn on and then my coffee starts brewing and I can, and it's like 5 45 in the morning because I'm going to teach Pilates and it's great.

So that's specifically the experience that I love. What about you, Preston? 

Preston: Me, it's gotta be a cortado. And I'm sharing my screen right now. Is this the Smeg coffee maker that you have? 

Margaret: Yes, but I have it in, I have it in light blue. That one in the bottom right. This, 

Preston: that is cute. I 

Margaret: it's so cute. 

Preston: Not, sponsored, but smeg, we love, [00:04:00] we, we love what you got going on.

Margaret: I want one of their toasters so bad I can't fork over the money for it. but 

Preston: do they have a fridge too? 

Margaret: That's never gonna happen. Our podcast would really have to pop off for 

Preston: Yeah, 

Margaret: for 

Preston: that fridge. So, I, my, my brother-in-law's from Costa Rica and like his whole family's down there, so we've gone to visit a couple times and Costa Rica's whole thing is drip coffee.

So. I found this out as, I was going down there 'cause I like espresso and I was like, oh, the espresso's gonna go crazy there. Which it did. But every time I was asking about like different espresso roasts or beans, like the cost Ricans would be like, nah, we can do it. But like our thing is drip coffee.

And I think one person told me at some point that I love espresso so much, I should just go to Italy. Which like made sense. but one thing I really liked about Costa Rica is. How precise they are about their bean growing. [00:05:00] So, coffee beans go really well in high altitudes and like, like moist areas.

So any place that you can think of that's like mountainous and jungley is like great for growing coffee beans. So like Costa Rica, Columbia, Ethiopia, I believe. anyways, all that stuff aside, I, whenever I think about good drip coffee, I think about Costa Rica. Me, I'm an espresso guy, so, so it'd be Italy, which I've not been to Italy actually, ironically, really just, my, my machine's from Italy.

It's a lelet. Which, 

Margaret: and how, when did you discover that, like espresso was the way you liked, like when did you first start drinking coffee regularly? 

Preston: Probably in college, and I only consumed it as a means to an end. So I remember, like I was at the, I was at the Air Force Academy and I would have like 10 minutes to eat in the cafeteria, and I distinctly remember like pouring the coffee from like that giant VAT they [00:06:00] had.

Margaret: Yeah. 

Preston: And then just grabbing like a handful of ice cubes and shoving it in there and being like, iced coffee. But I literally just made it iced coffee so that I could drink it faster and then go to class. Like, like it was like 

Margaret: warm coffee, like 

Preston: bottoms up. You know, this terrible coffee, you're gonna try your best to drink.

Margaret: I similarly like, well I started drinking coffee every day when I was like 15 because I was like, had my first job when I was 15 at this like daycare. And I had to be there at like six in the morning, which is early when you're 15. And so my older brother, Patrick, which Patrick, don't say, I never mentioned you on the podcast.

Yep. 

Preston: Patrick, 

Margaret: don't Patrick worry about it. Patrick, 

Preston: you've 

Margaret: been mentioning, he's been like, should, I come on the podcast? And I'm like, no. But he, I will get in this. He like, I was like getting up for my first day of like ever of work and he was like working in a construction job that summer. So he also had to be up really early.

So he came into my room with this. Old mug that was full of our dad's horrible love you dad, but [00:07:00] horrible Folgers, like drip coffee and it had like a ton of milk and like probably a third cup of sugar and a straw, like a bendy straw. And he goes, just drink this and trust me. And I was like, it, I don't want, I don't like coffee.

It tasted. And he's like, just trust me Maggie. I'm like, sat next to me while I drank it. And then he was like 20 minutes later he was like, how do you.

Preston: You just unlocked this memory of being in the back of a car, like my dad's driving me to a, like an early morning soccer game. You remember those like commutes? Weekends, we have a sports game somewhere. My dad's like, wake up. Wake up. Here's some caffeinated chocolate. And I think I was like 10. I was like, dad, this tastes so bitter.

And then I remember afterwards him being like, yeah, how are you supposed to play in the game? You're in the back just sleeping. And I'm like, you need to get locked in, or whatever the equivalent saying was at the time. So that was probably one of my earliest experiences with caffeine. 

Margaret: It's like, Dumbledore, you have to [00:08:00] keep drinking.

You have to keep, 

Preston: oh, you guys 

Margaret: keep drinking professor? 

Preston: Like, no, but I, actually do like caffeinated chocolate now. Awake. 

Margaret: Oh, really? 

Preston: Here. Those, chocolates are awesome. Awake 

Margaret: mentioned. 

Preston: I love those. Yeah. Awake. if you like the podcast, we, like you. but all our caffeine habits aside. We actually do have something interesting to talk about with coffee, and it's more than just coffee.

It's also tea. So, the paper that we're talking about today, this is coffee and tea intake, dementia risk, and cognitive function by, Dr. Wang and colleagues. And what I kind of had planned for the episode is we're gonna kind of discuss. The, format of the paper itself. We're gonna kind of go through how they approach this study and then we're gonna look at the findings, and then we're actually gonna go take a, global view and talk about their [00:09:00] overall discussion and conclusion.

And if, you know, we agree with it and what we kind of think some of the limitations of it are. So we're gonna take a quick break and when we come back, we will get into the paper.

Margaret: Sometimes emotion regulation looks like sensory comfort. And for all of my sensory comforts, I like Preston is showing on the video right now, use cozy earth blankets, comforters, and socks. What do you use to comfort yourself, Preston? 

Preston: I mean, I would show you the socks that I'm wearing, but I'm too comfy under this cozy earth cuddle blanket to get up.

I'm actually not sure if I'll ever get up again. I might just live here. 

Margaret: Well, we'll talk about that later, but what you can trust is that there's a hundred sleep. Guarantee to be able to return any products that aren't fitting with you. But we think you probably won't make many returns and there's a 10 year guarantee.

Preston: So use our code patient@cozyearth.com and make sure you include us in the post-purchase survey because we did send you, 

Margaret: and in the meantime, we [00:10:00] wish you a lot of emotion regulation. You're gonna need it. Mm-hmm. For the rest of this episode, 

Preston: or at least a blanket.

I always love that, kinda like going through these because I, like remind myself of the, like, epidemiology training that I had or like those, practice questions we took. So there's, there are like. Cohort studies and case control studies and they have associated like outcomes that we're looking for.

If you're in med school, you remember like going through all this stuff. This one is a cohort study, so for those that aren't familiar, essentially this is where you follow a group of people and then you see what happens to 'em. So they are starting out with this cohort from the NHS trial, and that's not the National Health Society, that's the N Nurses health study.

And the, health professions FS trial, which is just a bunch of doctor, male doctors. Doctors. [00:11:00] 

Margaret: Is 

Preston: it doctors or male professionals? 

Margaret: Male health professionals, 

Preston: yeah. 

Margaret: is it just like broadly male health professionals? 

Preston: Mm-hmm. So there's, that's actually the two genders. So, so both of these groups were enrolled in between like 19 75, 19 80.

They had about. 120,000 nurses between ages 30 and 55, enrolled starting at in 1976, and then there were about 51,000 male healthcare workers in 1986 enrolled between the ages of 40 to 75. Now these are like giant studies that multiple papers have come off, like it wasn't. They didn't do this study just for this one.

Coffee tea intake paper. Like the, nurses' health study has multiple arms. They start cohorts at different times. So I think they have another cohort. They started in 2001, another one they started in 2020, I believe. And there's been a lot of really important data that's come out of the, the nurses' health study.

Like they got [00:12:00] information on the association between OCPs and cancer risk. It uncovered a lot to do with, like these, the strong associations between, cardiovascular risk and smoking. So there, there are many things that have come out of studying this cohort. So this is just kind of like the, one of the most recent things.

Margaret: Yeah. And this paper came out in February this year. Right. 

Preston: So more, more fresh than that. Folgers Coffee your brother brought you. 

Margaret: Hey. That half cup of sugar helped. 

Preston: Yeah. Yeah. Well, hopefully won't, we won't need a cup of sugar for this one. The, hypothesis overall is that. Increased coffee, tea, and c and overall caffeine intake will be associated with a lower risk of, instance of dementia.

And kinda like looking at the broad like scientific method applied here we have our independent variable and ever dependent variable. So the independent variable is like gross caffeine intake, which was kind of actually the second variable. The first one was, coffee, tea, and [00:13:00] decaffeinated coffee intake.

Margaret: I, I just wanna pause just in case for people like. Also who maybe aren't used to this form of what we're doing in terms of journal club. I think one of the things that is pointed out in the paper as well is just to say at the top, the question for the paper is what they are trying to find out from this cohort is long-term intake of caffeinated and decaffeinated coffee associated with risk of dementia and cognitive outcomes.

Just to put that out there concretely like that is what everything else we're about to talk about is describing the methods of how they're trying to see. If their kind of original assumption or question is answerable from the data, 

Preston: right, because that's how hard cold, complicated science is done. You, ask a question and then you figure out how to answer it.

You don't just think really hard about it and decide what you've concluded. 

Margaret: You don't say, I did the research and my grandma experience this. 

Preston: Yeah, exactly. Because there are a lot of people that are asking this question. [00:14:00] Does, long-term caffeinated beverage consumption have any association with the risk of dementia incidents?

And I think, they put together a great answer. So, so when we kind of take that question, parse it out into how do you investigate it, we then have those independent variables. Independent variables like we talked about. So the independent being, how much caffeine, coffee, tea are you consuming? Then the dependent variable variables being subjective, cognitive decline, or how much you perceive your, like thinking to decrease.

And also incidents of dementia. either diagnosis of like Alzheimer's, Parkinson's, things like that. So remember, dementia is a clinical syndrome, not necessarily, as not necessarily associated with one singular neurodegenerative disease. So. When we're looking at, like, how they parsed out the, the cohorts, this is a, giant group, right?

So we have, I wanna say like 150,000, 170,000 starting potential candidates between the [00:15:00] 120,000 from the nurses' health study and the 51,000 from the, male health professionals. they went through some exclusionary criteria, so. If you recall, like some of the men started between ages 40 and 75. So some people actually already had dementia at the start of this study.

So those were, those people were excluded. Anyone with cancer was excluded. And then, anyone who just did not include their, caffeinated intake was excluded. So for most people, like even if they said zero, that was answering your caffeinated intake, but some people just like were lost of all that, all.

So those people were excluded and then. The last group that was excluded was, people with implausible reported energy intake. 

Margaret: Preston, why do you think that they excluded those people? 

Preston: I think it's really just like a question of the, validity of the answers that you're getting. Mm-hmm. I mean, like humans are notoriously bad at self-reporting.

there are plenty of studies that we do where you ask someone how many calories they think they eat in a day, and [00:16:00] then you follow them with a, a clipboard and record how many they eat. But people that are like that far off the mark, it's like, how close are you to everything else? And, for context, the implausible energy consumption rates were like less than 500 calories a day for females.

And I think for males it was 

Margaret: less than 800 than or greater than four. 

Preston: Two than 200. Yeah. That's a lot of calories. 

Margaret: Yeah. 

Preston: Or, a little. So 

Margaret: why do you think they've excluded people with a history of cancer? 

like specifically cancer? I don't know. I actually don't have an answer for this, but I thought that because I have like dementia and then Parkinson's, which makes sense to me.

But then cancer was interesting as like a, an illness, broad illness subset to, to carve out. 

Preston: Yeah, I'm not sure. I think it was just like, it's so strong of a confounder, in itself for like other, either caffeine consumption or cognitive decline. 

Because, 

one of the outcomes we're looking at is [00:17:00] subjective, cognitive decline, which could be like directly related to cancer and it's, a whole body illness that I think is like hard to parse out.

They did other subgroup analysis, but I think they were just, did not want to include cancer in that. 

Margaret: But like the thing is, and maybe it's 'cause like that can be parsed out more of whatever, but it's just interesting that like category was input there. 'cause you could make a similar argument for like, I don't know, a history of substance use or a history of like, psychia, like there's other comorbid with dementia, things that I would think more than the, so anyway. Interesting. And just, sorry, I, I do love digging into this throughout of just like, why, do we think that they excluded that? 

Preston: No, it's good.

and like I can frame myself as interpreting your hypotheticals instead of like, when you ask like, why do you think they didn't include cancer? It's like. that sends me into like med student mode, you know, like, 

Margaret: oh, no, I don't mean to, I'm sorry. 

Preston: And I don't, think you're pimping me.

but I was just like, oh God, no. [00:18:00] I didn't even think, 

Margaret: but I feel like this is like such a good example for like, when we talk about like, what is it that you do in med school and residency or like people who are actually in research. We're not primarily researchers at this point in our careers, but like what does it mean?

We talk in like literature a lot or in art about like staying with the art and really like taking it in and thinking about it and like a journal club done well is doing that where we really we're not necessarily, you know, I'm not gonna, I'm not trying to pimp you, I'm really just trying to think out loud together, but like when it's done well, it like really helps us understand.

Sort of like when we did with the, like your brain on chat, GPT, like why this amount of time? It's like, oh, well it was actually just a logistical thing. We didn't have money to do this or like, whatever. or this other piece of research showed us that this is the thing. So 

Preston: yeah. And I like it when there's, that simple of an answer.

No, I'll, survive. So I'll just press and projecting. so, so we got, [00:19:00] we have our cohort that we have our exclusionary criteria, and then there is. 121. Oh, sorry. 130,000 left standing after they were excluded. It feels like a, game show and the, contestants still love to drink caffeine.

One 30,000 view, like we're on like a Mr. Beast video or something. So then we actually have to look at how we're following them up. Their dietary and cognitive assessments. So every two to four years people would reach out and, call the participants and ask them to fill out these, validated, I think FSQ or FFS questionnaires, essentially all the things that they're eating over the course of a week.

Those questionnaires have been validated against like other seven day dietary patterns. So they feel pretty good about actually the, quality of information from the people reporting plausible. Calor can take what they're eating. And then for the cognitive assessments, there's kind of two [00:20:00] branches to this one.

So they gave everyone a subjective, cognitive question over the phone. They essentially asked them yes or no questions, seven total questions. Do you feel like you're having less energy to the day? Do you feel is your concentration's declining? Is it harder for you to remember things? Stuff like that.

And then if people answered yes to more than three of those questions, that was kind of considered like. Significant or positive. and then they did actual objective cognitive testing where they had people recall things from the Boston naming test. They had them say digits forward and digits backwards, and this was all done over the phone.

So it's actually, it's, impressive the amount of manpower that goes into these studies. You're calling hundreds of thousands of people and doing like subsets of the moca with them over the phone. So I just kinda wanna take a moment and say, wow guys, that, that is incredible 

Margaret: and thank you [00:21:00] nurses and male healthcare professionals, whoever you are, male healthcare professionals.

Yeah, thank you for doing that. Probably amidst your many hours of shifts 

Preston: just to can imagine you're in this study, you finish a 12 hour surgery. All you wanna do is go home and they're like, do you have a second to do digits forward and digits backward 

Margaret: for the love of the game? 

Preston: Oh God, fuck this study.

Why don't I join 

Margaret: this? 

Preston: And then, looking at the dietary intake, more focused, they divided people into quartiles for their caffeine consumption. So if you look at, coffee, tea and decaffeinated, coffee they had. The first quartile, which is the low, the lowest amount of consumption, which was essentially zero cups per day, and then the next quartile was less than a cup per day.

So most people are beating like 0.2 and 0.8 cups per day. You're not like literally drinking 0.8 cups per day, but it's like I'll have a cup of coffee every other day or every third [00:22:00] day. And then after that was one to 2.5 cups per day. It was the third quartile and the fourth quartile, the highest was two and a half or more cups per day.

And interestingly. The females in, like the nurses cohort I know consumed much more coffee than the men. Yeah. So each, quartile was like a little bit staggered. Like the most, the highest quartile for men was like two cups or more a day. And for women, the highest quartile was four and a half cups or more a day.

Margaret: Well, it's, interesting to think about like how, again, I don't know, and I'm sure this data is available that we could look into, but like. Did, does the study control for night shift does the study control for the, like most nurses were, are working twelves and I think they were working twelves still even then, maybe longer.

And was there a variety of like male healthcare professionals that were in all in light that those changed a lot and then just like, probably other things related to lifestyle and things, but it, is, I did [00:23:00] notice that it's interesting that it's like a much higher average in terms of like the quartiles for women.

Preston: Mm-hmm. I, this is probably not based in anything, but I was just picturing those giant Starbucks iced coffees in like a stately cup. I know, but this is not that 

Margaret: timeline. 

Preston: Yeah, you're right. Yeah. I guess this is, I mean, I mean some of it's within the last 20 years, the last 10 years because is 

Margaret: it, when did it end?

Preston: This is every two to four years. 

Margaret: Oh, and is it ongoing? 

Preston: Yeah. 

Margaret: Oh, okay. So at some point it was, so 

Preston: I'm not 

Margaret: sure what is the 1980s version of, that. 

Preston: Yeah, it's like diner coffee. 

Margaret: Yeah. 

Preston: but, they did control four and I'm glad you're bringing that up. Is, smoking, BMI, a POE four alleles and Alzheimer's disease polygenic risk factor scores.

So, essentially. And, for those that aren't familiar when you're controlling in these kind of cohorts is you compare all the results among the subgroups. So [00:24:00] for that like quartile of people that don't drink coffee, you then divide them further into people who don't drink coffee and smoke and compare within those people.

And people who don't drink coffee and don't smoke because you don't want it to be confounded. Like basically variable that affects both the a star and the outcome. and those were like the biggest. Confounding for the, development of dementia that they wanted to control for. 

Margaret: One of the things, I guess, and this just to point out to our listeners for this paper, one of the reasons that they are looking at coffee versus tea versus decaffeinated coffee, which is not zero caffeine, but is, much, much lower.

And then I don't know how much. Caffeine is in tea and they also didn't like specify what kind of tea that was in one of the limitations in the paper. But the point of this is to like look at like caffeine versus like organic compounds in coffee. That might be helpful [00:25:00] because if like decaf coffee was as good as regular coffee and there was no benefit in tea or something with caffeine, then it would be like, oh, it's not the caffeine factor.

This is part of why these groups, just for some, for our listeners, for some explanation of like, why do we care about decaf versus regular, 

Preston: right? 'cause, because you can imagine someone would reasonably come up and if you say like, Hey, drink coffee is good for you, must be the caffeine. And they're like, well, maybe it's just the coffee and caffeine has nothing to do with it.

the, and I just looked it up. So Decaffeinated coffee still contains about five milligrams of caffeine per eight ounce cup. So they, clear about 97% of the caffeine from it. So there's trace amounts in there, and then Yeah, like tea it, it's gonna vary by the tea type, which has the most caffeine.

I think black tea has the most caffeine. Green tea has a decent amount caffeine too. But each of these, they also have their own separate independent organic compounds. 

[music]: Mm-hmm. 

Preston: Like right within coffee and within tea. Yeah. So kind of like now getting into [00:26:00] the interesting and important results, and I'll break this kind of down by quartile.

[music]: Mm-hmm. 

Preston: I'm gonna read off right now is the, respective incidents for each quartile per 100,000 person years, and that a person year is kind of an abstract metric, so we'll try to explain it now, but it's essentially like if you're looking at an aggregate group or population data, it's the total amount of years to live.

So, I don't know why the, easiest metaphor for me is to look at like. Risks of like car accidents, where instead of like person years, it's like car miles or something. So, you know, if you're trying to, talk about like what is the risk of a tire, blowing on a Honda Civic, they will say, okay, for, you know, one Honda Civic, it might be a certain risk or another, it's a higher risk, but.

If you're only driving one [00:27:00] Honda Civic like two, and from the grocery store and the other one you're driving across the country, well, if you're looking all Honda Civics together, you just include the total amount of miles that every Honda Civic has driven. And then you take that and you divide that under the amount of tires that get blown.

So then it's like, okay, incidents of the event over total miles driven. So this is incidents of dementia who developed dementia over total amount of years lived by these patients. 

Margaret: Whereas if you could imagine in like the car analogy, like a different way to look at the statistics, could make things much more binary and make them yes or no, which is to say, did this car ever have a tire blow in its whole span?

Which would maybe help answer some types of questions about the car and buying cars in their use, but it doesn't answer the same types of questions that answering does the tire blow? Every 500 miles or every 2000 miles. And so I think, again, not a perfect analogy, but these different ways of moving the statistics around.

[00:28:00] First of all, I know we probably have some statisticians who listen to this podcast, and if you find errors in how we talk about this, please let us know because neither of us have a PhD in stats. The last time I checked and I think. That just as like an aside, sorry to interrupt you. 

Preston: We're trying and we get stuff wrong.

Margaret: No, I think you're getting this right, but this is just an aside, which is like he get, for our people listening, he's giving a heart, hands, fingers. this is why people get, we get pissed off about things where it's like a paper, like this comes out and then you see like a, an online publication or your favorite, like wellness TikTok or be like.

You see this study showed that there was a hundred more people with dementia or something if they didn't drink this coffee. And you know, it's even be and like misinterpret the data and we're like trying to be super careful and thoughtful after being in the field for like eight years. And be like, okay, I [00:29:00] think I'm getting the statistical analysis right, which we're not even getting into like real depth with this, like how they actually divided things out and like going into further things on that, which is just to say that this is very complex stuff and it's why we say don't jump to conclusions based on one paper.

But all that was an aside. I'm sorry, but I do feel like this is part of the point of journal clubs on this podcast is to be like, let's learn better and also see. What conversations do actually come up when we talk about it in depth. And don't just accept a headline. 

Preston: Yeah, Absolutely. And as easy and fun as it is for us to just throw headlines up and it get clicks, we're, here to, to yap.

So we gotta nuance. So, to get to the punchline now, so we, so per 100,000 person years. The first quartile that like low coffee drinking group had 354 incidences of dementia. And then going up to between, you know, [00:30:00] 0.2 to 0.8 cups per day, it was 302 incidences of dementia. Then at one cup or more was 2 26 and at two and a half cups or more was 94.

So there was actually like. You know, 354 incident of dementia per hundred thousand person years at no coffee or caffeine intake to down to 94. So it's almost a third for the group that was drinking, the highest amount of caffeine or moderate amounts. 

Margaret: A relative third. 

Preston: Yeah, relative third. and then taking that same data.

For decaffeinated coffee, they, converted that into TER tiles, which I'd never heard that before. It's like a quartile, but it's three, so it's a tertile and just, 

oh, 

Preston: it's just funny for me. 

Margaret: Oh, like tertiary? Yeah. 

Preston: Yeah. 

Margaret: Okay. As I said, we love root words here. 

Preston: Yeah. So, so basically the tuiles for decaffeinated coffee were no decaf coffee.

a little bit of [00:31:00] decaf coffee and a lot of decaf coffee and. Their incidence was 2 59 2 19, 2 62. So actually it was not unchanged between those who drank a ton of decaf coffee and those that really didn't drink any decaf coffee. 

Margaret: And was that, is 

Preston: interesting, 

Margaret: significant. Like was the p value significant for that?

like was there, because I thought there was overlap for the decaf. Like, like there was no significant difference when it came to the confidence. 

Preston: So 

Margaret: that could be the wrong term for this actually, now that I said that, but. 

Preston: I believe they did a two-sided, tea test for these, And they, I ign would decaffeinated coffee and then they were significant for the quartiles between the caffeinated coffee and tea beverages.

So when we're talking about a p value, what we're saying is that this is the percent chance that it all could have just happened via chance and usually in statistics. We accept something if it's a [00:32:00] 95% chance of being statistically accurate, which the P value is just the inverse of that. So it'd be 0.5 or 0.05.

That's just how we present it. But a p value less than 0.05 means that, essentially there's a greater than 95% chance that this is not just random and there's a 5% chance that maybe looking at the data, it just randomly happened to line up like this. 

Margaret: Right? Yeah. 

Preston: Because there's always a chance, you know, you leave enough monkeys in front of a typewriter, they're gonna produce Shakespeare.

You happen to look at data, and then the correlation may come out of it, but it may actually not have a relationship. So this is significant or much more likely to have a relationship than not. 

Margaret: And that's why we gotta replicate the studies. Well, not this one, but you know what I mean? That's why we talk about that.

And then we talk about, yeah, 

Preston: you got time to call a hundred thousand nurses. 

Margaret: Maybe you do. 

Preston: If I put my mind to it, I might be able to 

Margaret: be like, can I make a hundred thousand new friends in this [00:33:00] hospital before I graduate? Yeah. Maybe. 

Preston: try. 

Margaret: I do know some people though, who it does seem like they know every single person in the hospital, and you're like, how do you, do this?

but if 

Preston: you could do this with social media, probably 

Margaret: That's true. Okay. So a lot of coffee. Good, but not kind of. Not too much coffee, decaf coffee. Not a big difference in dementia. 

Preston: Exactly. So, so that, that's relevant because now people are wondering, okay, is it just the caffeine itself that's making the 

Margaret: difference now?

Like, can I take my alani new and just call it a day? 

Preston: And we're gonna, we're gonna talk about the limitations really quick, and then we'll kind of get into like why it may just be the caffeine that's helpful. So. A couple things to keep in mind because this is pretty compelling data, that we have. basically a dose dependent or stepwise decrease in dementia incidents, with increased ca caffeine or coffee and tea intake [00:34:00] is that they did not differentiate between types of coffee and tea.

So whether you're taking green tea, black tea, you have robusta beans, Arabica, you're taking es, espresso shots, drip coffee, cortado lattes, who knows if one's better than the other? 

[music]: Mm-hmm. 

Preston: maybe everyone who's not drinking decaf coffee, they're all just going for drip coffee, and that's, the real benefit.

But who's, the same? Right. and it could be possible that, you know, the. The overwhelming amount of tea drinkers were drinking green tea, but there's like less benefits in black tea. Who knows? So that's just like one limitation. The other one is that correlation does unequal causation, which we always have to take into account.

So there could be a potential reverse causal pattern where we have to think of what if. Instead of caffeine preventing dementia. Dementia prevents caffeine. So it's possible that patients [00:35:00] experiencing prodromal development of dementia have actually just been lowering their caffeine intake. So what if when I start to get Alzheimer's, I just feel like drinking less coffee?

And that's why we're seeing that. And so in that case, caffeine would be the canary. In the coal mine that's signaling us that someone has dementia rather than preventing it from happening. So we always have to keep that into account. we're seeing a correlation, in this cohort study, but we can't assume perfect causation.

[music]: Mm-hmm. 

Preston: the other one is that we can't account for all the confounders, so. We did try to look at the confounders like smoking, BMI, the APO four alleles, which are the high risk fuels for Alzheimer's and the Alzheimer's, like polygenic risk scores. But there are many other confounders like socioeconomic status, you know, race.

I guess we did look at gender between them. but there, and there's technically an infinite amount of potential confounders here that we can't take into account. So we have to, always like cite that as a limitation and then. Finally the [00:36:00] objective cognitive testing was only really done in the nursing cohort.

So on the male cohort, they only did the subjective cognitive screen. They didn't actually do numbers forward and backwards. So there, there are some like differences in the groups. I think both groups were powered enough. We have, you know, 50,000 versus like 86,000 or 40,000 versus 86,000. So I think there's plenty of numbers, but there are possible differences in the groups and how they got data from 'em.

What are your thoughts about the limitations of the study? Does it, make you want to throw this thing in the trash? 

Margaret: No, not at all. I mean, I think probably similar to you that, well, I actually don't know what you think yet. I think that this is a really well, like, powered paper. It has limitations as all good papers recognized that they do.

I think you could come up with a million things that could confound it, even to the extent that like, is it actually the coffee? Like not. many things for correlating, but also like, is it the coffee, like as an [00:37:00] ingredient that actually is neuroprotective, or is it the fact that most people drink coffee and then they go and do more because of the neuroactive impact of the coffee?

And those other things are actually the things that make them, like they're more cognitively active. They have a job, they're engaging with other people socially that makes it, mm-hmm. Like that could be. 

Preston: Is 

Margaret: one of many possible 

Preston: is coffee a tool to a healthier lifestyle. And that healthier lifestyle is really what, preventing risk of dementia.

I think that's, a great point. And so we are gonna take another quick break and when we come back we're gonna talk more about these confounders and also dig a little bit into the science of why caffeine might be the thing that's helping.

Margaret. I loved your point about. Caffeine or coffee just being a tool to living a more active, healthier, more, maybe more social lifestyle. Because when I was thinking about the limitations of this paper, one place my mind went was those old, I guess they're urban legends now, but a lot of the [00:38:00] studies on wine and longevity.

[music]: Yeah. 

Preston: So if you remember in the late nineties and early two thousands, people would say, Hey, turns out if you drink wine, you live longer. Maybe it has to do with the antioxidant benefits of grapes and blah, blah, blah. And there's all this explanation and it turns out that this has now been debunked and it's probably because rich people are more likely to drink wine and it was being rich all along.

Yep. That was the most important thing about living. 

Margaret: It was like being rich and having friends was like, oh 

Preston: yeah. It's like, oh, that's 

Margaret: like universal healthcare, 

Preston: right. Once we controlled for being rich and looked at rich people with friends who do drink wine, rich people with friends that don't drink wine, was no longer beneficial.

And if anything, it was deleterious. And so the official advice at this point is no amount of alcohol is healthy or good for you. 

[music]: Mm-hmm. And 

Preston: even small amounts can have, Significant risks for [00:39:00] cancer, cardiovascular disease, X, Y, Z. So, so there's, we, do not say that alcohol's good or healthy for you, you should drink it.

But for a while we used to think that, and, that's what happens with these studies. And, one of the other things that they didn't include, when they did these initial studies was, the nuances in the groups that abstained from the groups that still drank. So actually there was a lot. Of unhealthy people in the groups that abstained because they were alcoholics for 30 years and then they quit drinking and still had a lot of the sequelae of those problems.

But when the study went through, they were like. Do you drink? How healthy are you? Wow. People that don't drink are kind of healthy. 

Margaret: It turns out tequila is good for you and I'm sponsored by them. 

Preston: It's like, no, they stopped drinking because they didn't wanna die. No, you're just asking them they drink or not.

Margaret: Can I tell you something related to our, so while we were doing this and we asked what kind of coffee were the nurses drinking [00:40:00] in the eighties, I texted my dad who trained in the eighties. Wow. And I said, dad, what kind of coffee were the nurses drinking in the eighties? And he goes, yes. They were drinking a lot of coffee, bad coffee that tasted like cigarette butts.

And then there was a problem with leaving styrofoam cups sitting around and where all of us would write our notes. They had a huge stack of charts in the back. So that was live from the eighties. Hospital coffee, 

Preston: maybe it was cigarette butts all along that are preventing the dementia, 

Margaret: but there was also more smoking around.

They didn't, down from the cigarette around the hospital. Then I think it was like there was cigarettes being smoked outside the hospital by nursing doctors and all staff and still, and then there was also just the like dregs upon dregs of coffee that was like where the coffee hospital, the hospital coffee came from.

So I just wanted to, you gotta give a personal source if you have one, right? 

Preston: Yeah. That's great. I'm back when spilling coffee on the chart was a problem. You can just, I know, pull a KU on your phone. So, cigarette [00:41:00] butts aside, caffeine and coffee has its own specific things that may be helpful. So there's.

no neuroprotective and stimulating properties in caffeine. And this has actually been established in, a couple different papers, that have at least just looked at associations between decreased incidences of, dementia and caffeine consumption. I think this is the most powered one, high powered one that I've seen, but it's not the first to come to this conclusion.

One of the possible mechanisms of caffeine and preserving, cognitive function or, preventing instance of dementia is the antagonism of the adenosine receptors. So the A one and a two receptors are blocked by, caffeine, which suppresses the proliferation and accumulation of a beta amyloid. So.

It may literally like stop the like kind of clumping of the proteins that we know to be [00:42:00] associated with dementia. It also might lower pro-inflammatory cytokines. So these are things like our interleukins or our prostaglandins that lead to inflammation in astrocytes that might cause scarring or be more likely to contribute to downstream.

Immune or inflammatory processes that hurt your cognition? I, don't want to go too far into the weeds of this, partly because I don't have the ability to, but also it's some, I feel almost like a little

wellness when I say like, it decreases inflammation. 

Margaret: Right. 

Preston: You know, but it, actually does. Attenuate inflammatory responses in your brain and, that is helpful for, preventing against cognitive decline. 

Margaret: I mean, I think that's one of the true things about like, like is like the wellness world takes claims that are like actually true [00:43:00] and then amplifies them to the point that they're not true and then makes them somehow hyper exclusive and niche rather than just like.

A cup of coffee and a walk might be good for your brain. And it's like I have a, coffee with mushrooms and ecstasy in it. And then you're gonna do this very specific walking protocol also. Also it's an NMA cost 200. And also 

Preston: because, you want the true anti-inflammatory properties, it's gonna bypass, your liver, 

Margaret: right?

We're gonna give your liver the week off. We're gonna give all the rest of your organs a bad time. 

Preston: Next up eyeball shots with nausea. So the other, possible benefits of, caffeine may be more indirect. So, we know that caffeine affects insulin sensitivity in a good way. It makes you more sensitive to insulin, which you rarely hear about.

Usually it's you're less sensitive insulin than more prone to diabetes. I had [00:44:00] a, call the other day, say. You know what Type three diabetes is And I was like, what Kenny? And he goes, Alzheimer's, which is, it's a way to put it. I don't, know if I agree with that claim, but ultimately, if you have elevated levels of high blood sugar, it can cause damage to adherence to the like structural tissues in your blood vessels, which increase your risk of dementia.

And so anything that's gonna lower your risk of developing diabetes may also lower your risk of dementia. 

[music]: Mm-hmm. 

Preston: And then, finally, we haven't talked much about the tea, but there's obviously caffeine tea, but tea also contains l-theanine. Green tea does, and oh my gosh, I'm gonna mess this up. It's, epi Togo, Kain, EGCG.

Which, also has a lot of anti-inflammatory benefits. It, inhibits the [00:45:00] production of, pro-inflammatory cytokines as well. So there are some compounds that are unique to tea that are not in coffee, that they have their own both pro cognitive and anti-inflammatory benefits. The other thing in coffee are, these phenols or phenol lenanes.

So I became interested in these because they taste really bitter. And when I'm trying to like dial in my espresso shot, you actually, there's, like different, like a acidics and like, linolenic acids that make it more like kind of sour at the beginning of the shot. And that comes out really early when you pull the shot.

But later in the shot, these phenols, these alkaline phenyl linin come out and they make it, the shot tastes more bitter. If you do a good job of balancing that out, like when you time the espresso shot, you can actually get to a pH of like six or seven, and it tastes pretty smooth. But if you screw it up, well, if you fuck it up, [00:46:00] you, can have a super sour shot of a pH of like three or four, or you can like, you know, get above seven and taste really bittery.

Margaret: Do you wanna tell 'em that you have pH strips? 

Preston: I have. So I got pH strips and I started dropping my coffee on the pH strip 

Margaret: wine. Just gotta see where I was at. Drop acid. And you're like, yeah, I'm making coffee. Do you wanna call wine? I'm gonna dunk tomorrow morning and order a dunk a latte and be like, can you make sure the pH of that is.

Alkaline the shot. I need the shot at the forward part to be a little sour and they're gonna be like, bitch, this is a Dunkin donut. 

Preston: I would like extra phenol lins. If you could do that, please. 

Margaret: can you pH test it? Okay. 

Preston: Anyways, these, fennel lins, they actually have been shown in vitro to inhibit both tau and, a beta amyloid aggregation.

The only compound we've seen, human brain cells, both. Yeah. Only one we've seen that does both of them. 

[music]: Interesting. 

Preston: So it's also really [00:47:00] fascinating. So, but all that decaffeinated coffee that has lenanes in it and they didn't see any difference in the subject, in the incidence of dementia. So 

Margaret: yeah, this is where we run into a lot of the stuff where I feel like there becomes issues with a lot of, like, on one hand, like I think nutritional psychiatry has a lot of good evidence for broad, kind of simple changes, people's diets.

But I do feel like this gets in that realm too, and the like. The like, lead, author, not the first author, but the last author of this paper does work in this and is, does great research, but I think this is what you run into in this kind of research, which is hard, which is like. Actual science, trying to figure out what element of this food or compound or whatever is helping and then not having it be taken by the wellness world and be like, it is that element in it.

And so we hyper concentrated it in a lab and now you can shoot it into your nose and. [00:48:00] You're never gonna be 

Preston: introducing Linde nasal spray 

Margaret: Hyper. Yeah. 

Preston: Don't worry about the headaches. That's just your, the plaques being broken up.

And if your nose is bleeding, it's because the inflammation's going down. It's a good thing. 

Margaret: It's a good thing. It's the inflammation and the spirits are coming out of your nose, out of your body. The four humors are perfectly balanced now.

Preston: Well, that was all I really had for the, scientific mechanisms of it. 

Margaret: I have one, I have, one thing. 

Preston: Oh yeah, go for it. 

Margaret: I looked for, one of the things that I learned when we were doing our episode on chat, GPT, with the paper and with the paper's author, was to actually look for context of the author talking about the paper that exists.

And you were tricky with this one 'cause this one just came out, but. they, the Harvard Gazette did a piece on this article. shout out, [00:49:00] mass General Brigham Communications. Not a real person cited, but they quote Daniel Wang, who is the, like, primary like lead I think of this body of research. He is quoted as saying, while our results are encouraging, it's important to remember that the effect size is small.

And there are lots of important ways to protect cognitive function as we age, which is the most scientist thing to say ever, which is like, yeah, I worked on this for a long time, but like, you know, take it with a grain of salt. All research is just, we're all just seeking truth. And take it and don't run too far with it.

Preston: Yeah. Get back here. Stop that. Put your six cup of coffee down and 

Margaret: put you sleep. 

Preston: Please 

Margaret: don't misquote. And then the person who is the first author who's using Zang, who's a student at Harvard Trans School and a research trainee at Mass General Brigham said, we also compared people with different genetic predispositions to developing dementia and saw the same results.

Meaning coffee or caffeine is likely equally [00:50:00] beneficial for people with high and low genetic risk of developing dementia, which may be from a different study that they did, but I love when they get the first author and the last author in on this. Mm-hmm. 

[music]: So 

Margaret: take it. You know, this is, I import, this is cool work.

These are cool results. And they're not, they exist within, they didn't just fall off a coconut tree, the real world. Yeah. 

Preston: Shout out Kamal Harris. The, other thing that, they mentioned towards the end, which I think we know intuitively, which is if you drink too much coffee. That can lead to increased levels of anxiety and decreased levels of sleep, which also have their own like independent risk factors.

So we saw, and remember when we were looking at the effect size, it's greatest at the moderate level. And once you go past that, you know, three to four cups a day, they didn't get any additional benefit. Which part of it may just be you can't absorb anymore caffeine, but also. You start running into the deleterious effects of caffeine.

[00:51:00] So does it mean go jump on your caffeine fast and do six coffee enemas tonight? It's just 

Margaret: a deni. 

Preston: Keep doing all the healthy, normal things and your caffeine is not, as much of advice as it is if people say it is and you have this paper to show that. If anything, 

Margaret: I think that's actually super important.

'cause like the cortisol divas online that have been selling like adrenal fatigue stuff and like you have cortisol, this, that and the other. Love to be like. If you have coffee, it's stressing your body out and that's why you are ugly and broke and why you're gonna go to hell and whatever. But at least from the dementia risk 

Preston: can't get a boyfriend.

Margaret: You get a boyfriend because you're cortisol, you moon faces is what they're saying. Yeah. 

Preston: and it's all 'cause that coffee you drink 

Margaret: and it's just like, girl, just enjoy your coffee. Right. just let us enjoy our coffee. But yeah, 

Preston: this 

Margaret: is a really 

Preston: great take. I know a lot of people that they, say like, oh, I'm, trying to get off of caffeine.

I just don't wanna be addicted to something. Sure. You sure? You hear people say [00:52:00] that at one point? 

Margaret: Yes. 

Preston: And to that, I say, so what? Enjoy your coffee if you get withdrawal headache. Like, okay, but people that drink two or three cups of coffee have decreased, incidence of dementia and less subjective cognitive decline as they go through life.

So. If there are worse vices to have. You know, I always say, you know, there, there are people that are struggling with heroin use en enjoy your stuff. 

Margaret: You always say that 

Preston: mean, agree. Just like my grandma used to say. 

Margaret: We do, like, I think we've said this on here, this is not a carcinogen, but we choose our risk factors.

I always think, you know, we choose our own carcinogens and some are worse, some are better in terms of how quickly they will. Come home to roost, but 

[music]: mm-hmm 

Margaret: We all choose our own risks and I think we're here to just not fear monger you. Although I will say a lot of our listeners are healthcare workers and I think that you are drinking the coffee regardless, but 

Preston: exactly.

Margaret: Be confident in it. [00:53:00] 

Preston: Running is bad for your knees, not running is bad for your knees. At some point your knees are gonna give out, so, so just do what you feel like. That's 

Margaret: right. 

Preston: That's the existential part at the end. 

Margaret: Preston asked me when, if Lent was over yet, and I said no. And just to, give what you just said a little bit more.

you are dust into dust you shall return. So including your knees in the step challenge. 

Preston: Yeah, I gotta get on that. Okay. so. We're gonna step away and do the Patreon, section. 

Margaret: It's the private 

Preston: club section, which is gonna be me making espresso. I'm gonna bring you guys over to my espresso setup and we're gonna, we're gonna test out this, dementia, preventing elixir ourselves.

and then next time that I lead an episode, we're gonna be doing our final existential psychotherapy, bit on the meaning in our lives. 

Margaret: You can catch the next part of this on Patreon. 

[music]: It's [00:54:00] patreon.com/happy Patient Pod. 

Preston: and we are back from the Patreon section. That coffee smells good. I know Margaret can't smell it, but through the screen it looked good.

Margaret: it's 9:00 PM where I am. You're drinking coffee at nine 8:00 PM 

Preston: I drink coffee whenever. I feel like 

Margaret: you're sleep soon. 

Preston: Thank you so much for listening everyone. Thank you all for joining the step challenge. So some of y'all are magging us right now. I'm pulling up the results and I am 10th with you are 38,000 steps max.

I'm 

Margaret: 11. 

Preston: Good lord. 57,702 steps. Isabella is. 11,000 behind her at 46,000. And in a G 42,000, 617. So those are our top three. This is three days into the step challenge 

Margaret: Visa. Matt's 

Preston: currently 

Margaret: averaging thir like 12,800, which I'm like, those numbers aren't adding up, so I, it's. [00:55:00] She's at 57,000. 

Preston: That's, so I'm looking at her profile and her picture is, I think it's, I think this is a Tokyo's, it's the Tokyo Marathon.

Oh, 2026. So like, she did not come to play. She's probably the middle of her like marathon training right now. And she's like, oh yeah, I'm just get the steps, 

Margaret: get in here. shout out also to the DM who said. who said we need to ban marathon runners, and I said, or we need to rise their level. And I just got a thumbs down 

Preston: there.

There are 68 of y'all in the challenge so far, and, if you want to join, it's still not too late. Basically, if you get the Pacer app, it's free to download. And then once you get it, it will sync to your Apple Fitness account. And then it will just it'll retroactively include all the steps that you've been getting over the week.

So if you have an Apple Watch or anything that's tracking your steps, you can still join later on and you won't be, you know, zero while, [00:56:00] Mags has 150,000 steps. 

Margaret: And you can, you'll be somewhere in the middle. Listen to the podcast. You can listen to the Patreon. You can also do what I do, which is I can only, scroll while I stroll for the most parts.

so I can only be on TikTok when I'm on my little walking pad or commuting home and like waiting for the bus, walk. Tick, walk. Yeah. Walk, yeah. Walk, talk, walk, talk, walk, 

Preston: talk. that's probably better. Wach talk. I 

Margaret: like that. Like walk kind of, it kind of has something to it. 

Preston: Tick, tick, walk and talk.

Anyways, 

Margaret: I walk it while I talk it. 

Preston: Whoa. that's good. I like that. Or I make stir fry while I scroll, so that literally, I also walk it while I talk it. 

Margaret: Let's, talk about how good the song Stir Fry is on the next episode, but let's, we will leave it there. 

Preston: Let us, know what you think of this show, how the step challenge is going.

can y'all send us DM us pictures of you walking for your step challenge so we can repost them on our story [00:57:00] because we've been having, we will do that a lot of fun with this. We'll, 

yeah, 

like always. You can find us on Instagram TikTok at human Content Pods. How to be patient. Instagram page now has more than 4,000 subscribers or followers.

There 

Margaret: will be a season, 

Preston: there will be a, there will be a fifth season. We've been renewed by ourselves. 

Margaret: are we on the 

Preston: fourth season to all the listeners that are what? 

Margaret: We're in our fourth season right now? 

Preston: No, we're in our third season. 

Margaret: Okay, so it'll be a fourth. 

Preston: I'm skipping. I 

Margaret: was like, 

Preston: and a fifth season we get to five.

Margaret: Yeah. Endless 

Preston: five. 

Margaret: Endless. 

Preston: Yeah. Actually I'm don't wins to that challenge. You get 

Margaret: to be our third co-host. Sorry. Okay. We gotta, end this episode guys. 

Preston: you can always find full episodes on, my YouTube at its pre or on Spotify, apple Podcast, wherever you wanna listen. We're your host, Preston Roche and Margaret Duncan.

Our executive producers are me, Preston, Roche, Margaret Duncan. Will Flannery, Kristin Flannery, Aron Korney, Rob Goldman. Shahnti Brook, our editor and engineer [00:58:00] is Jason Portizo. Our music is Bio Mayor Ben V. To learn more about our program, disclaimer, ethics, policy submission verification, licensing terms, and our HIPAA release terms, go to how do be patient pod.com or reach out to us at how to Be patient@human-content.com with any questions or concerns.

How to be patient is a human content production,

[music]: how to be patient.

Preston: Thank you for watching. If you wanna see more of us or if you wanna see, this is lilac. She's my cat. She's gonna be waving her hand at one of the floating boxes, which will lead to more episodes. Lilac Point to the other episodes. Lilac doesn't know what the internet is, but I swear they're there. They, probably exist for real, but in the meantime, I'm just gonna pet lilac and then.

I'm gonna go dance in the [00:59:00] background.