Vaccines Show Surprising Link To Reduced Risk Of Alzheimer’s

Well, the anti-vaccine community is not going to like this one.

A growing body of evidence, buttressed by a new report out last month, shows that people who are vaccinated have a significantly lower risk of Alzheimer’s disease.

Yes, that’s right: in addition to the obvious benefit of protecting you from infections, multiple different vaccines have now been shown, in two large studies, to be associated with fewer cases of Alzheimer’s.

How big is the effect? Well, the earlier study, published about a year ago, looked at the flu vaccine. Scientists from the University of Texas Health Science Center, led by neurologist Paul Schulz, collected data on more than 1.8 million older patients from around the U.S., of whom half had received the flu vaccine and half had not. Their average age was 74 years, and the scientists examined health records for four subsequent years to see how many developed signs of Alzheimer’s in that time.

In the vaccinated group, nearly 48,000 patients (out of 936,000) developed Alzheimer’s during the four-year follow-up period, about 5.1% of all patients. That might sound like a lot, but in the unvaccinated patients, nearly 80,000 developed Alzheimer’s. To put it another way, patients who got the flu vaccine had a 40% lower risk of Alzheimer’s, 5.1% versus 8.5%.

It appears this benefit isn’t specific to the flu vaccine, though. In the newer study published this September, the same group from the University of Texas looked at three more vaccines: the Tdap vaccine (tetanus, diphtheria, and pertussis), the shingles vaccine and the pneumococcus vaccine. They were able to collect records on 1.65 million people, among whom more than 500,000 had received one or more of the vaccines. All of the patients were over 65 years old.

Remarkably, all three of the vaccines showed similar and quite significant benefits against Alzheimer’s disease. In an eight-year follow-up period, the risk of Alzheimer’s was 30% lower (7.2% versus 10.2%) in patients who had the Tdap vaccine versus those who hadn’t. For the shingles vaccine, the reduction in risk was 25%, 8.1% versus 10.7%. And for the pneumococcal vaccine, the risk was 27% lower, 7.9% versus 10.9%.

(Note that this study looked at the older shingles vaccine. The newer one, Shingrix, has only been widely available since 2017. The scientists hypothesize that the newer vaccine, because it’s more effective against shingles, may provide even greater protection against Alzheimer’s.)

So how might this work? Is Alzheimer’s caused by an infection, and the vaccines prevent Alzheimer’s by preventing the infection? Well, the short answer is no, probably not. Although we don’t know the cause of Alzheimer’s, we don’t have any strong evidence that it’s the direct result of an infection.

Furthermore, with data showing that at least four different vaccines offer similar levels of protection against Alzheimer’s, the evidence indicates that the effect cannot be specific to the flu vaccine, or the Tdap vaccine, or with any of the other vaccines or their ingredients.

The University of Texas group that published the study speculated that vaccines might work to protect against Alzheimer’s by “long-term reprogramming of innate immune cells,” also called “trained immunity.” This hypothesis is far too complex to try to explain here–and it involves immunology, which I don’t really understand myself and which is “absurdly intricate” as science writer Ed Yong put it. So let’s just say that this is an intriguing idea that needs more research.

And for anyone who thinks that getting an infection and recovering (instead of getting vaccinated) might offer the same benefit, that doesn’t seem to work: another study looked at precisely this question and found no connection between the number of influenza infections and the risk of Alzheimer’s. So the vaccine seems to confer a benefit that the disease itself does not. (I mention this because a popular–but wrong–claim of anti-vaccine activists is that you get better immunity from infection by catching the disease and then recovering. Not a good idea.)

Also, I have to add that these studies report correlation, not causation. So even though the effects are large and significant, we don’t know for certain that vaccines do something to directly prevent Alzheimer’s. Maybe people who get vaccinated also have other behaviors that help them avoid Alzheimer’s–although the study design tried to minimize this possibility.

Vaccines have enormous, extensively documented benefits: they prevent suffering and disease, and they’ve saved countless millions of lives. And now it appears that they offer something else: a lower risk of Alzheimer’s. So if you haven’t received your boosters, now you have one more reason to get them.

Most of our common cold medicines don’t work

We still don’t have a cure for the common cold. In your local pharmacy, though, you can find many shelves filled with products that claim to treat the symptoms.

Well, it turns out that one of the most widely used ingredients, long believed to be effective at treating congestion, doesn’t work at all. The ingredient, phenylephrine, has been in use for decades, and it’s in many common cold medicines that are taken by millions of people each year, including Nyquil Severe, Sudafed PE, Robitussin CF, Tylenol Cold & Flu and others.

It turns out that phenylephrine was never properly studied for effectiveness. How can this be? It’s FDA approved, which usually means it has to be safe and effective, right? Not exactly, as I explain below.

As for phenylephrine: well, the studies have finally been done, and last month an FDA panel unanimously concluded, after reviewing the results, that phenylephrine is “useless and no better than a placebo.” It probably won’t cause you any harm, but it won’t have any effect on your stuffy nose.

To understand how this happened—and why it might be true of many other FDA-approved remedies that you can buy at the pharmacy—you have to know about how the FDA approval process has changed over the years. Pharmacists Randy Hatton and Leslie Hendeles, who worked for years trying to get phenylephrine properly reviewed, explained in a recent New York Times editorial that when the FDA was originally created, way back in 1938, it was only required to ensure that drugs were safe.

At the time, that was tremendous progress. Prior to 1938, drug manufacturers could claim pretty much whatever they wanted to.

But it wasn’t under 24 years later, in 1962, that Congress required the FDA to show that drugs were also effective. Therefore the thousands of drugs approved prior to 1962 were mostly safe, but they might not actually treat the disease they were intended to treat. After 1962, the FDA created a process to check those previously approved drugs, but they’ve never had enough staff or funding to check most of them. So phenylephrine was never properly reviewed, until now.

What’s next for phenylephrine? The FDA might ban it from the market, but that will take time, and it might not happen, because the FDA doesn’t have to follow the advice of its panels, although it usually does. Meanwhile, you can still buy cold remedies with phenylephrine, and they still claim to treat congestion.

And don’t even get me started on other treatments that are not only ineffective but that aren’t even subject to review by the FDA, such as homeopathic remedies. These include Zicam, which claims in large print on the front of its packaging that it “shortens colds.” It doesn’t, and Zicam’s manufacturer doesn’t even have to prove it, because it’s homeopathic. If you zoom way in one of the labels on the Zicam website, you’ll find the disclaimer that “Claims [are] based on traditional homeopathic practice, not medical evidence. Not FDA evaluated.” On some of the packages, I couldn’t even find the small print.

(Aside: Congress protected homeopathic preparations from FDA scrutiny way back in 1938, thanks to a homeopath who was also a U.S. Senator, and who helped write the original FDA legislation.)

I wrote about Zicam and other ineffective cold remedies in 2014 (”The Top Five Cold Remedies that Do Not Work”), and that advice still holds. Now we can add another one to the list.

We simply don’t have any drugs that work particularly well for the common cold, despite the many claims you can find online and on the labels of so-called cold remedies. The best thing you can do is just drink warm liquids such as tea or lemon-infused water, stay home and get plenty of rest.