PodMed Double T is a weekly podcast from Texas Tech. In it, Elizabeth Tracey, director of electronic media for Johns Hopkins Medicine, and Rick Lange, MD, president of the Texas Tech University Health Sciences Center in El Paso, look at the top medical stories of the week. A transcript of the podcast is below the summary.
This week’s topics include impact of firearm laws on childhood deaths, healthy lifestyle and genetic risk of Alzheimer’s, systolic versus diastolic blood pressure and cardiovascular outcomes, and cognitive reserve, physical activity, and Alzheimer’s.
0:44 Genetic risk and Alzheimer’s
1:44 Moderate genetic risk with lifestyle
2:44 Absolute reduction small
3:40 Systolic and diastolic blood pressure and cardiovascular outcomes
4:41 Both independently predictive
5:41 Routine blood pressure measurement
6:11 Cognitive reserve, physical activity, and dementia
7:11 Also had objective assessment
8:11 Lower vascular risk, engage in educational activity
9:11 Do have some control
10:00 State laws and childhood gun deaths
11:10 Stricter gun laws had lower rates
Elizabeth Tracey: Can you overcome Alzheimer’s risk with a favorable lifestyle?
Rick Lange, MD: For blood pressure, is it the upper number or lower number that affects cardiovascular outcomes?
Elizabeth: And back to Alzheimer’s — what about cognitive reserve and physical activity?
Rick: Do state guns laws affect pediatric firearm-related deaths?
Elizabeth: That’s what we’re talking about this week on PodMed TT, your weekly look at the medical headlines from Texas Tech University Health Sciences Center in El Paso. I’m Elizabeth Tracey, a medical journalist at Johns Hopkins, and this will be posted on July 19th, 2019.
Rick: And I’m Rick Lange, President of the Texas Tech University Health Sciences Center in El Paso, where I’m also Dean of the Paul L. Foster School of Medicine.
Elizabeth: Rick, you asked me when I sent you the studies for this week, “Gosh, we’re doing an awful lot related to Alzheimer’s,” and that’s because the Alzheimer’s Association international meeting is taking place right now. So that accounts for why we’re focused on that topic. We’re going to turn right to the Journal of the American Medical Association. Can you trump your genetic risk for Alzheimer’s disease or other types of dementia with a positive lifestyle?
This is a pretty big study, almost 200,000 people were enrolled in it, and they took a look at them for about 8 years. They gave them a bunch of risk scores. One of them was, “What’s your genetic risk score for developing dementia?” Twenty percent of the participants had a high risk score, 60% were in the immediate category, and 20% had low risk.
They also took a look at these folks’ lifestyles, including their diet and their exercise, and they graded them as favorable or unfavorable. And they found that you could moderate a little bit of your genetic risk for developing Alzheimer’s disease by adopting a favorable lifestyle.
Rick: I’m glad you picked this particular study because it highlights both things that play into the development of dementia, particularly Alzheimer’s. One is a genetic risk and the second is, can we modify that with lifestyle even if we’re at a high genetic risk?
What the studies show is that if you have a high genetic risk and an unfavorable lifestyle — that is if you don’t exercise and you smoke and you drink heavily — and you don’t have a healthy diet, compared to those that have a low genetic risk and have a healthy lifestyle, there’s a three-fold greater incidence of developing Alzheimer’s. However, the absolute percentage is fairly small.
So when you take the high genetic risk and you say, “Let’s add a good lifestyle on to that,” it lowers the risk from about 1.8% to about 1.1%. That means about 120 people that are at high genetic risk need to exercise for one of those to not develop dementia. So there is a benefit — there’s no question about it. However, unfortunately, it’s relatively modest.
Elizabeth: I guess I would say that since we don’t really understand all of the etiology of dementia right now, maybe going ahead and adopting a healthy lifestyle is going to have lots of other benefits, and it could ultimately end up impacting on one’s dementia risk, even in the presence of genetic factors.
Rick: Yep, and as you suggest — and we’re going to talk about some other studies — maybe initiating these things even earlier can help either delay or prevent the development of dementia. So we’ll talk some more about some of these other studies that support the fact that a healthy lifestyle and other things that we do can actually modify our risk even if we’re a high genetic risk.
Elizabeth: Which of yours would you like to pick? We could either turn to the New England Journal of Medicine or the study in Pediatrics looking at firearm deaths in kids.
Rick: Well, since we’re talking a little bit about lifestyle, let’s talk a little bit about blood pressure for a while, specifically about the relationship between the higher number, the systolic, and the lower number, the diastolic, and whether either one of those or together predict cardiovascular outcomes. Part of the reason we’re talking about this is because there has been some discrepancy.
In other words, early on, 40 or 50 years ago, we thought the lower number was more important. More recently, individuals said, “No, it’s the higher number that you need to pay attention to.” Then we also had varying definitions of hypertension. Is it people that have a blood pressure over 140/90 or is it over 130/80?
The great virtue of this particular study is it involved 1.3 million adults in a general outpatient population. This was in the Kaiser Permanente system and they had over 4 million blood pressure measurements. And they looked at those measurements and actually looked at whether they developed a heart attack or a stroke over a period of 8 years. What they discovered was that each of the numbers independently predict the outcomes.
Now, the higher number was more predictive — it was about twice as predictive as the lower number — but both were independently predictive. So there are some people that only have an elevated upper number, some that only have an elevated lower number, and some that have both. What the study shows is that we need to pay attention to both.
Furthermore, this increase in cardiovascular outcomes was associated regardless of whether you started at 140/90 or 130/80. It didn’t really matter. Anything that elevates either of the blood pressures is associated with an increased cardiovascular risk.
Elizabeth: And so this study, of course, is in the New England Journal of Medicine. What does this tell you about appropriate, sort of, monitoring of blood pressure over time? Should we be monitoring people in their 20s for their blood pressure and watching how that changes, say, per decade?
Rick: That’s a good point. What we know is as all of us age our blood vessels become harder, stiffer, and the blood pressure ends up going up. So for example, if you’re 80 years old, the chance that you will have hypertension is about 8 in 10 individuals.
There’s an increase over the course of time, but you shouldn’t wait till you’re 50 or 60 to measure your blood pressure. It should be done even at a younger age. Any time anybody sees a dentist or goes to their doctor for a routine visit, there should be a blood pressure measurement.
Elizabeth: What about the diastolic number? Would you treat that independently with antihypertensive agents if only that was elevated?
Rick: Elizabeth, that’s a great question. What this study would suggest is, yes, because anything over 80, there’s a gradual increase in mortality even in people that have isolated diastolic blood pressure elevations.
Elizabeth: Let’s go back to Alzheimer’s disease. We’re going to treat these two studies in JAMA Neurology together. One of them took a look at this issue that’s ongoing, and of course, it’s something that’s of interest to you and me. That’s cognitive reserve — and the idea that if we are educated, if we continue to challenge ourselves with learning and with new skills and with brain games and so forth, does that impact on our risk for developing dementia?
[It was a] much smaller study, about 2,000+ participants in the Rush Memory and Aging Project. They followed these folks for a mean of 6 years. What they found was that if you took a look at cognitive reserve and you had high cognitive reserve, middle, and low cognitive reserve, the highest cognitive reserve was associated with reduction in dementia risk, even in participants with high Alzheimer’s disease pathology. In these folks, they actually evaluated them with objective criteria to see whether or not they had all the stuff in their brains that indicated that there was an accumulation of the things we think are related to Alzheimer’s disease.
Let’s go to the other one before you make your comments, which is physical activity and beta amyloid, and does that make a difference with regard to prediction or neurodegeneration in people who entered the study who were normal? This is part of the Harvard Aging Brain study. They actually quantified these folks’ physical activity with a pedometer. They had 182 included participants in this particular analysis.
They analyzed the beta amyloid in their brains and they also looked at their vascular risk, and they found that greater physical activity and lower vascular risk independently attenuated or reduced the negative association of having a lot of beta amyloid in your brain with cognitive decline and neurodegeneration. This is in people who were not clinically showing that they had signs of dementia yet.
So, [what] things [can] we can do? Engage in greater physical activity, lower our vascular risk by … let’s go back to our blood pressure study here. Then engaging in a lot of educational activities and things that help improve our cognitive reserve seem to lower risk modestly.
Rick: Again, the value of these particular studies is, one, they document what we suspected. People that had a high cognitive reserve or people that were healthier had less dementia. But what about the individuals that are at high risk of dementia? We talked about genetic risk a minute ago. Now we’re talking about actually brain pathology and people that have amyloid in their brain. One is a postmortem exam. The other is with PET imaging.
And you might throw up your hands and say, “Gosh, I’m at a high risk. It doesn’t really matter.” But even in those circumstances, these lifestyle changes could reduce the risk of Alzheimer’s by about 40%. So even people that are at high risk — genetic, high risk because of brain pathology, high risk because of amyloid in their brain, they can still modify the risk or progression of Alzheimer’s by doing these lifestyle changes. We do have some control.
And it’s interesting. We’ve tested a number of drugs that try to prevent the progression of Alzheimer’s, and they have not been successful. These lifestyle changes apparently are successful.
Elizabeth: I would point out, however, the difference between the impact of the lifestyle changes on people who are already at genetic risk versus those who have what we think is the Alzheimer pathology because that’s a really important thing. We do see — and have seen — in a multitude of studies this purported Alzheimer pathology that was not associated with cognitive decline in various populations.
Rick: You’re absolutely right. So the presence of amyloid protein doesn’t mean you’re going to get Alzheimer’s. Conversely, for those individuals that will develop it, these lifestyle changes still reduce that risk by about 40%.
Elizabeth: And that’s good news. Speaking of things we can do, let’s turn to our final one in Pediatrics, state laws and their impact on childhood gun deaths.
Rick: Many of our listeners may not be aware that firearms are the second leading cause of pediatric deaths in the United States. We’ve talked before about the fact that gun laws affect adult mortality related to firearms. The question is do state guns laws affect pediatric firearm-related mortality?
So the authors attempted to answer this by doing a cross-sectional study from about 2011 to 2015 where they looked at what’s called the Injury Statistics Query and Reporting System and census data. So they measured both strictness of firearm legislation, which is they had a gun law score from 0% to 100%. How strict were a states gun laws?
And secondly, they looked to see whether there was one of three new gun laws that had been shown to affect adult-related mortality, that is background checks for firearm purchases, universal background checks for ammunition purchases, and identification requirements for firearms.
What they discovered was during this period there was a total of about 21,000 children that died of firearm-related injuries, but states that had stricter gun laws had lower rates of child mortality related to firearms. For every 10% improvement in strictness of firearm legislation, there was a 4% reduction in pediatric deaths. But more importantly, if the state had a law that required universal background checks to purchase a firearm, it decreased children firearm-related mortality by 35%. Good evidence that not only do background checks and strict gun laws reduce mortality in adults, it also reduces mortality in children as well.
Elizabeth: Yep. And a worthy goal. I think we need to advocate for that as well as support pediatricians and others in asking about safe gun storage and all kinds of other devices.
Rick: Yeah, and that’s part of the strict gun laws. I was surprised when I looked at the data, Elizabeth. Most of the gun-related deaths were in the 18- to 21-year-old range, and about 60% was homicides, and about 35% or 40% were suicides. So this is older kids being able to get their hands on guns in states that either have lax laws or states that don’t have background checks. There’s been a reluctance to talk about firearm-related studies. I think we can address this if we actually look at the evidence and do so in an unbiased way.
Elizabeth: On that note, that’s a look at this week’s medical headlines from Texas Tech. I’m Elizabeth Tracey.
Rick: And I’m Rick Lange. Y’all listen up and make healthy choices.