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In memory of the man who put red and green squiggles under words

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Every little thing in a graphical user interface that we take for granted today, no matter how small, was thought up by someone, at some point. Case in point: the little red squiggly lines underneath misspelled words. In one form or another, these are everywhere now, and have just become a regular staple of every single text editing field we encounter every single day and don’t stop to think about. Still, they were invented by someone, and we happen to know exactly who that was: Tony Krueger.

In early versions of Word, the Spell Check feature was something that you explicitly invoked, and then you had to sit and wait while the program looked for all your potentially-misspelled words, and then showed them to you one at a time for a decision on what to do for each one. Word did introduce an Auto Spell Check feature to run spell check when the user was idle, so that when you hit the Spell Check button, the results were ready to go. However, the Auto Spell Check was still a blocking operation. As a result, a lot of users turned it off because it always seemed to decide “Now would be a good time to spell-check the document” just as you wanted to do something, forcing you to wait for the spell check pass to complete before you could, say, save and exit.

Tony made the spell checker much more unobtrusive so that it didn’t interfere with your foreground work. And when it found a problem, instead of waiting for you to trigger a spell check, it immediately drew red squiggles under potentially-misspelled words (and later green squiggles under potential grammatical errors).

↫ Raymond Chen at The Old New Thing

Tony Krueger passed away recently, after, among other things, having worked on an dizzying number of Microsoft Word releases. Imagine coming up with something that seems to basic and elementary to us now, and seeing it spread pretty much everywhere. I wonder what it must feel like to have invented something that seems so simple, most people don’t even realise they use it every single day.

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mareino
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satadru
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Asphalt and inertia: The deeply flawed $16.4 billion Chesapeake Bay Bridge plan

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Ocean City’s tourism industry is looking sunny. Hotel vacancies are down, spending is up. Even traffic has improved: Where once 118,000 drivers crossed the Chesapeake Bay Bridge every Friday, Saturday, and Sunday of the summer, today just 94,000 do the same. This is not due to lower demand but the post-pandemic work week. Workers once squeezed by rigid work hours into three-day weekends can now take their time by heading out on Thursday and coming back Monday.

But Maryland’s planners have not kept up with the times. Citing years-old models projecting explosive weekend travel demand, the Maryland Transportation Authority (MDTA) plans to spend $4.4 billion to widen the Chesapeake Bay Bridge from five lanes to eight on top of the $12 billion overall replacement cost.

The now-$16.4 billion project – some 2.9% of state GDP – is the result of profound bureaucratic inertia built up over a decade of work. MDTA damned transit with a geographic double standard and comically poor cost and ridership models, and it relied on pre-pandemic travel demand forecasts based on optimistic and static land-use plans to demonstrate a surge in demand, thereby excluding narrower options. After the pandemic, MDTA never revisited these decisions, locking the state into a trajectory for a destination that no longer exists.

This is not simply about the state’s passive acceptance of a decades-old, highways-first planning process. It is about how Maryland’s institutions, grinding through that process, doomed a transit alternative, and how the state must now break the inertia of its bureaucracy.

The manufactured geography of asymmetry

Before doling out federal transportation funds, national environmental law requires states to clearly define their goals and rigorously analyze all options to meet those goals. In theory, transit has a fair shot at meeting these goals, and by law it must. In practice, states can simply describe the project’s goals such that only roads could ever hope to meet them.

For the Bay Bridge, MDTA was able to take advantage of the existing highway networks on either side of the bridge to limit its scope to a single 22-mile bottleneck, stating that traffic could simply filter out on either side. Maryland could simply punt the impacts on the side roads and feeder roads to other projects and agencies.

MDTA afforded transit no such luxury. While the agency restricted its highway alternative to just one segment of the network, it forced its transit alternative to solve the entire 192-mile journey from DC and Baltimore to Ocean City.

This double standard was not born out of malice but of the deep rut Maryland has carved for itself. Over the past 80 years, the state government has spent billions of dollars to stitch together a highway system linking its every corner. It is only logical for highway planners to take advantage of this sunk capital, just as they always have, to restrict their work to a single geographic chokepoint. But doing so blinds them to the cascade of traffic problems this project will cause, the economic drain caused by those new problems, and the cost to fix them. Transit planners cannot afford such blinders.

Golden rails, ghostly riders

The geographic disparity was only the first blow against transit. Next came costs. For these, MDTA drew not on peer intercity rail projects but on the quintessentially urban WMATA Silver Line, effectively modelling a $321 million-per-mile Metrorail extension to Ocean City, using today’s dollars. This would make it even more expensive than California’s pricey high speed rail project, which is now projected to cost a relatively modest $184 million per mile.

A more realistic North American analogue, the 180-mph Brightline West from Los Angeles to Las Vegas, costs just $98 million per mile, while slower diesel projects like TEXRail can be delivered for a mere $49 million per mile.

Buses were not immune from such inflation, either. Rather than model a modest high-occupancy toll lane within the 22-mile limits of the project, which would have cost effectively nothing, MDTA used the now-cancelled Corridor Cities Transitway, which would have run throughout urban Montgomery County at a cost of some $75 million per mile, and stretched it over the same 192-mile journey.

Costs per mile (2025) Total cost (2025)
MDTA Heavy Rail $321 million $61.6 billion
MDTA Light Rail $289 million $55.4 billion
MDTA BRT $75 million $14.5 billion
California High Speed Rail $184 million $35.3 billion
Brightline $98 million $18.9 billion
TEXRail $49 million $9.4 billion

Having inflated costs to absurd heights, MDTA then suppressed ridership in ways that border on comedy. Most ridership models for transit take into consideration the totality of the service on offer: its speed, its frequency, and the places it serves. MDTA dispensed with such complexity. Using 2017 ridership data from mixed-traffic commuter buses and travel patterns that date from George W. Bush’s first term, MDTA assigned cities and counties a static percentage of travel to Ocean City that would be done by transit: 10% for DC, 5% for Baltimore, etc. Any intermediate ridership potential, and any data from this decade, were ignored entirely.

The result was an infinitesimal ridership projection. MDTA confidently concluded that just 0.7% of corridor travel would be done by transit on weekdays and 1.14% on weekends, no matter how fast or slow the train, no matter if the bus had its own lanes or fought through gridlock, no matter how many trips per day were scheduled, no matter where the stops were located.

Tautologies of travel demand

Defenders may concede that the MDTA’s study was flawed but insist that its conclusions were valid. Maryland’s model of future travel demand, the one that predicts 135,000 trips per summer weekend day, projects that planned land uses and developments will be scattered rural and semi-rural places that cannot be well-served by transit. Spending billions on a transportation project sized for summer demand would be a waste. Besides, even if travel demand has slumped, it would be irresponsible of the state to abandon the Eastern Shore to future congestion.

As Queen Anne’s commissioner-at-large Jim Moran fatalistically put it to Baltimore Magazine’s Lydia Woolever: “Will there be more traffic? There always will be more traffic.”

These defenses are politically convenient but analytically hollow, relying on an artificial divorce of land use and transportation capacity. The state’s forecasted summer travel surge, for instance, is derived from local land use plans that are static and optimistic, entirely immune to how congestion impacts development viability or land value.

Localities, banking on driving remaining the only viable option, have planned accordingly, and the state is making its decisions based upon how localities believe the state will make its decisions. In short, Maryland says a wider bridge must be built in order to meet travel demand that will very likely only materialize if a wider bridge is built. And because these localities banked on driving at the outset, regional transit will remain boxed out. It is a tautology dressed up as a model.

Yet even this is not the end of the state’s methodological flaws. MDTA left travel demand management tools like congestion pricing out of the final analysis because these tools could not solve congestion on their own. Apart from its use of an unfair baseline and absurd assumptions in analyzing transit, MDTA never actually modeled transit using state travel demand forecasts. And MDTA ignored its own estimates that a modern bridge could carry 6% to 11% more traffic per lane per hour than the existing twin span. As a result, a six-lane option, paired with demand management, never even advanced to the final analysis.

Taken together, a wider span seems to have been a foregone conclusion. By analyzing congestion pricing and bridge modernization apart from one another and apart from travel demand, relying on models that unrealistically divorce land use from transportation capacity, and sabotaging transit at every turn, the only option left standing was the $16.4 billion option. Even if an eight-lane bridge is the right choice over a six-lane option, the methodology and analysis are so flawed there is simply no way to know.

Breaking the inertia

As a result, MDTA must halt this process before it closes the book this November by issuing a Record of Decision and correct its methodological failures with a Supplemental Environmental Impact Statement. To do so it will have to rewrite the goals of the project to consider the entire 192-mile corridor, allowing roads and transit to compete fairly. And it will need a new travel demand model that realistically incorporates the inseparable link between land use and transportation, and which is based on contemporary data.

Finally, MDTA needs to assess a new set of alternatives that incorporate the complementary nature of congestion pricing, transit options, and modernized bridge lane capacity based on real-world analogues. MDTA must exorcise from its analysis the self-fulfilling demand models and shadows of the pre-pandemic world.

Any supplemental analysis will also need to incorporate Maryland’s statutory greenhouse gas reduction goals and transportation policies. Under the Climate Solutions Now Act, the state is required to reduce its greenhouse gas emissions to net zero by 2045 – the same year travel models predict 135,000 vehicles per day will cross the Chesapeake Bay Bridge.

To help achieve this goal, Governor Wes Moore’s administration has pledged to cut per capita driving by 20% by 2050. Either of these goals would be difficult for any government to meet, but they are not impossible. Alongside vehicle electrification, the state will have to unwind decades of highways-first planning. To achieve this, the state will have to aggressively and consistently expand transit and active transportation options, deploy congestion pricing, and encourage smarter land use policies before even considering pouring more asphalt. Only then could it possibly meet its goals.

A plan to spend a generational sum on the state’s largest highway project based on old data, inflated costs, and flawed models, however, is an active threat to the administration’s goals and the state’s duty of due diligence to its taxpayers. Maryland cannot allow the weight of its bureaucratic inertia to set such errors in concrete.

Top image: Maryland is intertia-ing its way toward an expensive plan to widen the Chesapeake Bay Bridge.  Image by Peter Burka licensed under Creative Commons.

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mareino
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Mosquitoes, already? Blame cars

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Maybe you, too, have already swatted away – or worse, been bitten by – mosquitoes despite the early date on the calendar. Usually, mosquitoes are a problem only in DC’s notoriously damp late summer, and especially given the bitter winter that just passed.

If you’re in central DC, you might be able to blame cars, or more specifically underground parking garages, for creating year-round mosquito sanctuaries. That’s the finding from “Paved Paradise: Below ground parking structures sustain urban mosquito populations in Washington, D.C.,” a 2021 article in the Journal of the American Mosquito Control Association by Arielle Arsenault-Benoit and Megan Fritz, two University of Maryland entomologists, and Albert Greene from the federal Public Buildings Service.

The study was prompted after federal workers at office buildings in Southwest DC complained about mosquitoes. Mosquito species known to carry tropical diseases, including dengue, Zika, yellow fever, and West Nile fever, were identified around these buildings in summer 2018 and 2019. Researchers visited nine below-ground sites at federal office buildings in central DC over the course of a year to log temperatures and collect both adult and juvenile mosquitoes.

Three of the underground sites harbored juvenile mosquitoes, indicating that mosquitoes were breeding there. Genetic analysis showed that the populations were related from year to year, definitively proving that the mosquito populations were established inside the garages rather than newcomers from outside.

Aedes aegypti mosquitoes spread diseases, and find year-round homes in local parking garages. Image by IAEA Imagebank licensed under Creative Commons.

Temperatures underground are pretty much constant at around 50 degrees Fahrenheit year-round. In years past, people took advantage of this fact to keep ice cold in summer and food unfrozen in winter; today, it makes geothermal heat pumps possible. It also means that even these unheated underground garages, open to the chilly air above but otherwise enveloped by the unfrozen thermal mass of the Earth, could maintain an average temperature of 52 degrees Fahrenheit and not drop below 41 degrees.

So any mosquitos that find a puddle underground can shrug off DC’s winter chill – the outdoor low that winter was 12 degrees. After all, the winters inside are as warm as in the Florida Keys. And puddles are plentiful underground; basement garages are damp and their drainage systems, which have to pump water up against gravity, are often sluggish.

Now that we know where mosquitoes are overwintering, they can be targeted more effectively. If you’re noticing mosquitoes early in the year around your home or office, talk to your building’s management and cooperate with neighbors, because mosquitoes don’t care about property lines.

Meanwhile, we can now add “reducing the chances for disease-carrying vampire insects to survive” to the long list of reasons to pursue parking reform. Nonexistent, or at least smaller and shallower, parking garages would offer fewer warm-weather havens.

Top image: Underground parking garages, like this infamous one in Rosslyn, are great places to hide spycraft – or tropical mosquito species. Image by the author.

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mareino
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Saturday Morning Breakfast Cereal - Spiraling

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Click here to go see the bonus panel!

Hovertext:
We were both spiraling, kids, when we found each other.


Today's News:



Red Button mashing provided by SMBC RSS Plus. If you consume this comic through RSS, you may want to support Zach's Patreon for like a $1 or something at least especially since this is scraping the site deeper than provided.
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Iran is Trump's Katrina

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Photo by Jocelyn Augustino via Wikimedia Commons

Young people won’t remember this, but there was a distinct point at which George W. Bush started to lose the country. In August 2005, a giant hurricane swamped New Orleans, killing over a thousand people and washing away whole parts of the city. Bush displayed startling incompetence and tone-deafness during the cleanup, which began a process of general disillusionment with his presidency that intensified with the financial crisis of 2008 and the long slog in Iraq.

I don’t know whether Trump’s debacle in Iran will be a similar moment for his presidency. For one thing, unlike Bush, Trump’s approval ratings were already very low before Iran:

Source: Nate Silver

Compared to the other stuff people hate about Trump — the blasé attitude towards inflation, the tariffs, the unprecedented corruption, the ICE raids, the various abuses of power — the Iran War may end up being a minor footnote. But there is one similarity with Katrina: This is the point at which even many of Trump’s defenders will be forced to admit, in private if not in public, that the man and his administration are grossly, pathetically incompetent.

The details of the deal that Trump is trying to make in order to withdraw from the war he started are still murky and unclear — probably because as soon as those details are released, people will realize that the U.S. has effectively been defeated by Iran. Here’s what the deal is rumored to contain:

(Update: Bloomberg has the confirmed details of the draft memorandum, and and the initial reports look to have been completely accurate.)

Plenty of people, looking at these details and observing the conduct of the war, are ready to speak the plain truth that the U.S. lost the war to Iran. Tom Nichols, a former professor at the U.S. Naval War College, had this to say:

Trump and his team, in record time, just lost a war to a militarily mediocre—but nonetheless extremely dangerous—adversary…[E]ven before we have the details, it is clear that Trump has failed to achieve every one of the goals he put forward for this war of choice, and now he is determined to sign, seal, and deliver America’s capitulation as quickly as possible.

The New York Times editorial board concurs, with the headline: “Trump Lost the War He Started in Iran”. The WSJ Editorial Board is slightly nicer, writing “Trump Stages an Iran Retreat”.

As regular readers of this blog know, I’m very skeptical of claims that America has “lost” this or that war:

For example, we clearly won the Iraq War, despite a generation of pundits who got used to repeating that we “lost”. We defeated all enemies — Saddam, various militias, and ISIS — and established a friendly, pliant government that allows U.S. oil companies unfettered access to the country. Bush’s war was a strategic mistake — in my opinion, the geopolitical benefits weren’t worth the costs — but by any reasonable historical standard, it was a victory.

The same is not true, however, of Trump’s war in Iran. This one really is a clear defeat for the U.S. The reason is not just that the U.S. failed to achieve its strategic goals. It’s how Iran forced the U.S. to give up those goals.

How Iran won the war

Iran used military force to defeat the U.S. First, it successfully dispersed and hardened its key forces — missiles and drones. This is from the Washington Post on May 7th:

A confidential CIA analysis delivered to administration policymakers this week…found that Tehran retains significant ballistic missile capabilities despite weeks of intense U.S. and Israeli bombardment…Iran retains about 75 percent of its prewar inventories of mobile launchers and about 70 percent of its prewar stockpiles of missiles, a U.S. official said. The official said there is evidence that the regime has been able to recover and reopen almost all of its underground storage facilities, repair some damaged missiles and even assemble some new missiles that were nearly complete when the war began.

And this is from CNN on May 21st:

Iran has already restarted some of its drone production during the six-week ceasefire that began in early April, one sign it is rapidly rebuilding certain military capabilities degraded by US-Israeli strikes, according to two sources familiar with US intelligence assessments…Iran’s military is reconstituting much faster than initially estimated…[S]ome US intelligence estimates indicate Iran could fully reconstitute its drone attack capability in as soon as six months…Iran has been able to rebuild much faster than expected due to a combination of factors, ranging from support it is receiving from Russia and China to the fact that the US and Israel did not inflict as much damage as the two countries had hoped, one of the sources told CNN…

Thousands of Iranian drones still exist — roughly 50% of the country’s drone capabilities[.]

Iran dispersed and buried both its weaponry and its defense industrial base, and the U.S. was unable to destroy it.

Next, Iran used its surviving weapons to execute an effective naval blockade of the U.S., and its key allies.

The naval blockade was Iran’s closure of the Strait of Hormuz. This vital waterway, which delivers much of the world’s oil, is right next to Iran, so Iran had the geographic advantage. It used drone boats, naval mines, aerial drones, and missiles to prevent ships from transiting the strait. This did two things. First, it raised the global price of oil, which raised gasoline prices in America:

It also sent U.S. inflation back to around 4%, which caused Americans’ real wages to start falling:

Meanwhile, the U.S.’ allies — the Gulf states and Saudi Arabia — were severely impacted by Iran’s blockade of Hormuz, since much of their oil couldn’t be sold. These allies put pressure on Trump to end the war.

The U.S. tried many things to open the Strait of Hormuz, but nothing worked. American strikes were incapable of destroying Iran’s weaponry or forcing Iran’s regime to submit. So in the end, it had to submit. The deal Trump is reportedly cutting makes huge concessions to Iran, leaving Iran in a much stronger position both economically and militarily than it was before the war:

  • The U.S. will withdraw its forces from the conflict zone within 30 days.

  • All U.S. sanctions on Iran are reportedly being lifted. Before the war, sanctions had crippled Iran’s economy since 2012, leaving it stagnant and sclerotic. With those sanctions gone, Iran will be able to sell oil and grow much more prosperous.

  • Iran will reportedly start charging fees on transit through the Strait of Hormuz. This is a toll on international shipping — something forbidden by the UN Convention on the Law of the Sea. This will be a huge source of income for Iran — something that didn’t exist before the war.

  • The U.S. and/or its Middle Eastern allies will reportedly pay Iran a $300 billion reconstruction fund, as well as unfreezing Iranian assets. This is equal to one entire year of Iran’s GDP, and would effectively constitute war reparations. JD Vance has said that the reconstruction fund is not yet confirmed.

Iran thus compelled the U.S. to withdraw its military, end the sanctions that were in place before the war, and potentially pay Iran reparations. In exchange, Iran will allow the Strait of Hormuz to open (with tolls) and will publicly declare that it’s not pursuing nuclear weapons (which it has always publicly declared in the past).

In addition, Iran will gain an important new source of geopolitical power and economic revenue: control of the Strait of Hormuz.

Before the war, Iran didn’t control the strait, simply because it didn’t realize it could. Drone technology had advanced to the point where Iran was able to shut down Hormuz, but Iran didn’t know that until the U.S. attack forced it to try the risky and desperate move of actually shutting down the strait. The gambit paid off spectacularly, and now Iran knows that modern drone weaponry gives it an advantage it didn’t have in previous decades. So it controls Hormuz.

It’s kind of wild to step back and consider how good of a position Iran’s leaders are in now, compared to the situation before the war. Iran had lost most of its proxy armies in the Middle East — Hezbollah, Assad, most of Hamas. The regime had been rocked by massive nationwide protests, which it only managed to quell by murdering tens of thousands of innocent Iranian citizens. The country’s economy was slowly dying. Now the leaders are firmly entrenched in power, their economy will be revived, and they find themselves the masters of Hormuz for the first time.

Anyway, I don’t see any sense in which this is not a classic military defeat for Donald Trump and the United States. Consider the contrast with Iraq. None of America’s opponents in the war were in power after the war; in Iran, despite the assassination of a few leaders, the regime is even more firmly in power now than before the war. In Iraq, the U.S. suffered some economic damage, but was willing to see the conflict through until all opposition was defeated and all U.S. war aims were achieved (except for the destruction of WMDs, which never existed in the first place and so could not be destroyed). In Iran, economic pressure forced America to make major concessions relative to the pre-war status quo.

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Dementia is rising, but your personal risk is falling | Vox

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I turned 48 this week, which meant it was time for my annual physical. After the usual battery of questions from my doctor — How much did I drink? Was I exercising? How was I sleeping? — it was my turn to ask a question. I had one prepared: Should I get the shingles vaccine?

  • Dementia cases will keep climbing as the population ages — a projected million new US cases annually by 2060 — but your odds of getting it at any given age have been falling for decades. An 80-year-old today is meaningfully less likely to have dementia than one a generation ago.
  • Across wealthy countries, age-specific dementia rates have dropped roughly 13 percent per decade since the late 1980s, and most of that decline tracks with things we can influence: better-controlled blood pressure and cholesterol, less smoking, more years of school. The brain lives downstream of the heart.
  • A 2024 Lancet commission estimated that up to 45 percent of dementia could be prevented or delayed by addressing 14 risk factors — and the highest-leverage window is midlife, not old age.
  • The anti-dementia to-do list: treat your blood pressure and LDL cholesterol, don’t smoke, stay physically active, get your hearing and vision checked, keep learning, and go easy on alcohol. Unglamorous, but it buys time for your brain.
  • A growing run of studies links the shingles vaccine to lower dementia risk. The evidence isn’t conclusive and the shot is only recommended at 50, but it’s worth a conversation with your doctor.
  • There is no drug that reverses dementia today. That’s not the same as being helpless.

According to standard medical guidance, the answer would be no. The shingles vaccine is only recommended by the government for people 50 years or older; the only exceptions are adults whose immune systems are weakened by disease or treatment. And despite the way my back feels when I get out of bed each morning, I wasn’t there quite yet. Our immune systems weaken as we age, but at 48, I was probably still capable of beating back the varicella-zoster virus that causes shingles (and chickenpox).

And yet my doctor was open to the idea for the same reason that I was asking about it: because there is early but growing evidence that the shingles vaccine may be protective against neurodegenerative diseases like dementia. For someone my age, with more time behind me than in front of me, the possibility of developing those diseases — and the desire to do anything to prevent them — is suddenly looming large.

I’m far from alone. Dementia already afflicts more than 6 million Americans today, and a 2025 study in Nature Medicine estimated that the lifetime risk of developing dementia after age 55 is 42 percent, with higher figures for women, Black adults, and those who carry the APOE ε4 allele genetic variant, which is known to increase the risk for Alzheimer’s. That same study projected new US cases of dementia would double by 2060, from 514,000 a year in 2020 to more than 1 million annually, due largely to population aging.

Behind those figures is a universe of suffering. Nearly everyone reading this has watched, or will watch, someone they love succumb to dementia. And once you get to my side of your 40s, that risk starts to feel less abstract and a lot more personal.

Yet the frightening story of the rise in dementia cases as the US population ages obscures real progress that is already being made to prevent it — and the even greater progress that could follow. Dementia may feel inevitable, a cruel side effect of longer life. But it doesn’t have to be.

The Nature study is about incidence — new cases, not the total number of people living with dementia. Separate CDC estimates project nearly 14 million older Americans living with Alzheimer’s disease, the most common form of dementia, by 2060.

But the rate hasn’t been holding steady — it’s been dropping. A 2020 study that drew on data from six countries across Europe and North America found that age-specific dementia incidence for people of European ancestry had fallen about 13 percent per decade since the late 1980s, and around 16 percent per decade for clinical Alzheimer’s. A 2016 study tracked five-year dementia rates across four periods between the late 1970s and the early 2000s and found them steadily falling, ultimately dropping 44 percent by the most recent period. The authors of the 2020 study project that if the decline in incidence remains steady in the future, 15 million fewer people might develop dementia by 2040 across high-income countries than if the incidence of the disease remained unchanged.

That good news may not be shared by everyone. The 2016 study found that the decline only showed up among people with at least a high school diploma — more on that below — and even then, it wasn’t evenly shared. And the sheer increase in older people means that a continually dropping incidence only blunts the coming dementia wave, rather than blocking it. One study of older adults in England actually found dementia incidence falling through 2008 and then creeping back up; the researchers also found that when you account for the fact that people headed toward dementia tend to die earlier, the drop gets much harder to see. What’s fallen before can rise again.

But what this likely means in practice is that a person turning 80 today is meaningfully less likely to have dementia than a person who turned 80 a generation ago. And it’s reasonable to hope the same will hold for whoever turns 80 next — like, say, me.

The question, though, is why.

Here’s a veteran health journalist tip: if anyone ever asks you why something is improving in public health, just attribute it to the decline in smoking. There’s a decent chance you’ll be right.

While Alzheimer’s is a brain disease, and dementia is the umbrella term for several kinds of cognitive decline, there is a growing consensus that they are deeply driven by vascular health — meaning what damages your heart and blood vessels is ultimately what damages your mind. Thanks to the development of blood pressure and cholesterol-lowering medicines, better heart disease and stroke management, and perhaps most of all, drastic reductions in smoking, cardiovascular health has been improving. Even with the rise of obesity and diabetes, most vascular risk factors have decreased over the same time that dementia and Alzheimer’s prevalence fell.

The rise in education over the same time period may play a role as well. Americans turning 80 today went to school during a great mid-century expansion in education, while their parents were schooled — or rather, not schooled — in the 1920s and ’30s. In 1940, only 24.5 percent of Americans 25 and older had a high school diploma, and just 4.6 percent had completed a bachelor’s degree or more. By 2017, high school completion had reached 90 percent, and the share of people with a bachelor’s or more had hit 34 percent. And researchers have correlated higher education attainment with lower dementia and Alzheimer’s rates.

Now repeat after me: correlation is not causation. Researchers don’t really know why more years of schooling seem to be associated with a lower risk of dementia, though there are theories that education might boost the brain’s “cognitive reserve.” But the hopeful take is that the decline in incidence is largely driven by behaviors and life conditions we can change. And one of the most unexpected and promising acts is something as simple as routine vaccination.

Last April, I wrote about what I called “one of the brightest spots in an otherwise dark field”: a study in Wales that found that older adults who received a vaccine against shingles were 20 percent less likely to develop dementia in the seven years following vaccination than those who did not receive it. It wasn’t a randomized trial, but it was stronger than the usual observational association: the study harnessed a natural experiment in Wales, where vaccine eligibility turned on a birthday cutoff, meaning it was less likely that the results were because vaccinated people were simply healthier.

Earlier this year, a study in Canada looked at hundreds of thousands of people over the age of 70 and, like the Welsh study, found that those who had taken the shingles vaccine were less likely to develop dementia. And a new analysis from late 2025 of the data in the Welsh study found that the vaccine was associated with benefits that went beyond prevention — it also seemed to slow the disease for those with dementia and reduced deaths attributable to it.

The shingles vaccine in the Welsh study was an older, live-virus version; the current vaccine is a newer recombinant form that can’t accidentally cause shingles, and another study found it was associated with even greater protection from dementia.

These findings are promising but still leave plenty of questions. The Welsh live-vaccine study found a larger apparent benefit in women, who also suffer higher rates of dementia. But the pattern is not settled: the newer recombinant-vaccine study found an association in both men and women, though stronger in women. Shingles may be connected to dementia, though the evidence is still messy: A large 2025 health-records study found recurrent shingles was associated with a modestly higher dementia risk than a single episode, while earlier evidence has been more mixed.

Shingles occurs when the dormant varicella zoster virus — the same virus that causes chickenpox — reactivates. It’s possible that the resulting neural inflammation may feed dementia. A randomized controlled trial published in December tested a related herpes-virus idea, treating 120 adults with early Alzheimer’s or mild cognitive impairment — all with evidence of prior herpes simplex infection — with a medication called valacyclovir. After 18 months, researchers found no significant advantage over a placebo, dampening hopes that herpes antivirals could be an effective Alzheimer’s treatment.

That’s a real strike against the simplest version of the theory that the virus itself is rotting the brain. But it could mean that the shingles vaccine’s possible protective effects don’t come from shingles at all. A 2025 study found that the newer shingles vaccine and an RSV vaccine that share the same AS01 immune-boosting adjuvant were each associated with lower 18-month dementia risk compared with flu vaccination, and researchers did not find a statistically significant difference between the two AS01 vaccines. The implication is that the benefit might come from giving an aging immune system a jolt, rather than from any one bug it’s aimed at.

But as the vaccine science sorts itself out, there are lifestyle changes you can make to help protect yourself without getting a shot. A 2024 Lancet commission found that, in principle, up to 45 percent of dementia cases could be prevented or delayed by addressing 14 risk factors, including not smoking; lowering high LDL cholesterol in midlife; treating hearing loss, especially from midlife on; and limiting obesity. The key period here is midlife, which the commission defined (rather widely in my opinion) as 18-65. Which, for someone my age, means there’s no better time to focus on prevention.

I don’t know whether I’ll go ahead and try to get the shingles vaccine early, and to be clear, I’m not telling anyone they should. The science is still uncertain, and I am, obviously, not a medical doctor. But the lifestyle factors that have been shown to protect against dementia — which are largely the same ones that help cardiovascular health — can be adopted by everyone, for their health now and in the future.

No one knows for sure what the future holds, for me or for you. What’s certain is that, barring a medical miracle, the sheer number of dementia cases will continue to rise as our population ages, and that some of us will be in that number. But that doesn’t mean we’re helpless.

A version of this story originally appeared in the Good News newsletter. Sign up here!

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Swati Sharma

Swati Sharma

Vox Editor-in-Chief

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acdha
7 days ago
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Close to home age-wise 💉
Washington, DC
mareino
7 days ago
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Washington, District of Columbia
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