JOHN YANG: Tonight on PBS News Weekend, Volodymyr Zelenskyy goes to London to rally European support after the fiery exchange in the Oval Office signals a rift in U.S.-Ukrainian relations.

Then, Canada braces for a trade war after trying to head off the steep tariffs Washington is set to impose next week.

And why medical experts say the risk of dementia for people over 55 is much greater than previously known.

MAN: If you're thinking about your lifelong health, it makes you realize that you need to consider the risk that at some point you may hit dementia before death.

(BREAK) JOHN YANG: Good evening.

I'm John Yang.

Tonight, Washington and European capitals are still feeling the reverberations of yesterday's heated Oval Office exchange between President Trump and Ukrainian President Volodymyr Zelenskyy.

Hours after Mr. Trump scolded Zelenskyy for not showing enough appreciation for U.S. support, the Ukrainian leader posted on X.

We are very grateful to the United States for all the support.

I'm thankful to President Trump, Congress for their bipartisan support and the American people.

He also reiterated his opposition to a quick ceasefire that President Trump wants, saying Russian leader Vladimir Putin can't be trusted.

Now Zelenskyy is in London to rally the support of European leaders.

Today he met with U.K. Prime Minister Keir Starmer, and tomorrow he'll attend a European summit in London to discuss the way forward.

Kurt Volker is a former U.S. Special envoy to Ukraine and a former U.S.

Ambassador to NATO.

Mr. Volker, what do you expect to come out of this European summit tomorrow that Zelinsky is attending?

KURT VOLKER, Former Special Envoy to Ukraine: Well, I think there are some good things that we've seen already, these expressions of European support and solidarity for Ukraine.

I think it's important for Zelenskyy psychologically.

I think it's also important for the Ukrainian people.

But I hope that behind closed doors they're actually talking about what kind of things need to be done to get Ukraine and the United States and Europe all on the same page again.

We can't be creating a dynamic of Europe and Ukraine against the United States.

We all have to pull together.

And there I think it's going to be a matter of Europe being willing to put on the table forces for security assurances for Ukraine.

And I think it's got to be President Zelenskyy saying that he wants peace.

He wants to have a ceasefire.

He will agree to one as soon as Putin to get things back on track with the U.S. as well.

JOHN YANG: If U.S. aid were to be cut or even go away, could Zelenskyy, could Ukraine go on with just European support?

Are there enough forces and hardware to keep them going?

KURT VOLKER: It's not enough.

It's good.

It is supportive.

It'll buy Ukraine time.

But the U.S. provides many unique capabilities, including intelligence, satellites, training, equipping, logistics.

There is so much that the U.S. is doing here that is vital to.

This is not enough Europe on its own, although it is very important that Europe play a major role.

JOHN YANG: You say it's important to get all three sides, Ukraine, United States and Europe on the same side, but in European capitals, aren't they seeing what happened yesterday and him, the way he talked and the way he talked about the war in Ukraine.

A message to Europe that you're on your own.

I mean, war in Ukraine, obviously, is about European security to the European leaders.

KURT VOLKER: No, I don't think that was the message.

I think the message was that we got to get Putin to the negotiating table.

You don't want to bash Putin, criticize him personally, and then never get an end to the war.

If you want to end the war, you got to get Putin to the negotiating table.

Basically taking a position that is firmly fighting against Putin.

Trump is not going to do that he wants to actually end the war right now.

And so he's being careful not to position himself that way.

Unfortunately, what happened in that meeting, Zelenskyy, I think, missed a real opportunity to get the U.S. and Ukraine in alignment.

Trump has been putting together this concept, if you will, of ceasefire reciprocity with Ukraine, where we get paid back for military assistance.

So it's a fair deal for the American people.

Deterrence in terms of security assurances and European presence so Putin doesn't attack again, and improving the burden sharing ratio so that Europe does more, the US does relatively less.

JOHN YANG: But since this meeting, he's also said that he doesn't want a quick ceasefire because he doesn't think Putin will keep his commitments.

Clearly, that's what President Trump wants.

How do you bridge that gap and save this relationship?

KURT VOLKER: Yeah, exactly.

And Zelenskyy needs to reframe the way he's talking about this.

Saying he doesn't want a ceasefire because he doesn't trust Putin is the wrong way to say it.

The way to say it is he wants a ceasefire as soon as Putin agrees to do that as well.

And it will never be Ukraine that is the first to break.

But if Putin breaks a ceasefire, Ukraine will defend itself.

He needs to flip it back onto Putin and say that Ukraine is willing and ready for peace.

It's Putin.

That's not.

JOHN YANG: Yesterday in the Oval Office meeting, we saw a continuation of a pattern of President Trump not criticizing Putin, as a matter of fact, expressing sympathy with Putin while excoriating the leader of the country that Putin invaded.

Why is that?

KURT VOLKER: Well, I think you have to go back to earlier in the meeting.

Trump was very positive towards Zelenskyy toward Ukraine praising Ukrainian soldiers.

He was setting this up to be very positive for Zelenskyy.

And it was only after Zelenskyy then responded to J.D.

Vance talking about diplomacy that it became a bit of a back and forth in an argument.

And then you saw Trump lash out and criticize President Zelenskyy.

As far as Putin goes, Trump is trying to avoid personalizing and demonizing Putin because he needs to get Putin to the table.

And I think President Trump thought he was getting this all together.

He was moving Putin that way.

He was working with President Zelenskyy.

He was shaping a deal that would put the U.S. And Ukraine in alignment.

And then that discussion, the Oval Office just got out of hand and blew everything up.

JOHN YANG: Former Ambassador Kurt Volker, thank you very much.

KURT VOLKER: Thank you.

JOHN YANG: Today's other news, phase one of the Israel-Hamas ceasefire ended today and talks about phase two of all but disappeared.

U.S. And Israeli negotiators are in Cairo with Egyptian and Qatari mediators who are representing Hamas, but no progress has been reported.

What's next isn't clear.

Phase two is supposed to include the release of more Israeli hostages and the ceasefire is to continue during phase two negotiations.

In phase one, Hamas released 33 hostages in exchange for more than 1,700 Palestinian prisoners and detainees.

It's estimated that 59 hostages remain in Gaza, half of them likely dead.

A federal court judge extended an order blocking President Trump's plans to pull federal funding from institutions that provide care for transgender youth.

The judge said two of the president's executive orders are unconstitutional because they treat people differently based on their transgender status.

It's a setback for the administration's efforts to limit official recognition of transgender people.

Three years after resigning in scandal, former New York Governor Andrew Cuomo is trying for a comeback.

As was widely anticipated, Cuomo said today he's running to be New York City mayor.

In a video announcement, he promised to guide the city out of social and political turmoil and lower crime.

He briefly acknowledged past mistakes.

In 2021, he resigned after a number of allegations of sexual harassment.

The Democratic primary is in June.

The Vatican says Pope Francis is improving after a breathing crisis.

Yesterday, they say the pontiff drank coffee and read newspapers during breakfast.

The Vatican also said Francis spent several hours today off of a noninvasive ventilator, a sign his lung function is improving.

He was put on the ventilator after a coughing fit led him to inhale vomit.

Today, health care workers at the Rome hospital where the Pope has spent more than two weeks with double pneumonia, made a pilgrimage to St. Peter's Basilica to pray for the 88 year old pontiff.

And David Johansson, the frontman and last surviving member of the 1970s band the New York Dolls, has died.

The glam rock group was the forerunner of punk, made a big cultural impact, but was never commercially successful.

Johansson's greatest commercial success came in a solo career as his lounge lizard alter ego Buster Poindexter.

David Johansson was 75 years old.

Still to come on PBS News Weekend, with tariffs expected to go into effect on Tuesday, we explore last minute efforts to avert them and the growing risk of dementia in adults over the age of 55.

(BREAK) JOHN YANG: President Trump says his 25 percent tariff on imports from Canada will go into effect on Tuesday, despite the efforts of Canadian officials who've been trying to persuade their American counterparts that they are working on border securities and have improved it.

David McGuinty is Canada's Minister of public Safety.

This week he's been in Washington meeting with administration officials.

I want to remind people the reason President Trump says he's opposing these tariffs.

He posted this on Truth Social.

He said drugs are still pouring into our country from Mexico and Canada at very high and unacceptable levels until it stops or is seriously limited.

The proposed tariff scheduled to go into effect on March 4th will indeed go into effect.

What do you say to that?

DAVID MCGUINTY, Minister of Public Safety, Canada: I think what we say is we've had a wonderful four days here in Washington, D.C. meeting with our counterparts, both folks in the Senate, the House.

I brought down the head of our Canada Border Services Agency, brought down the head of our RCMP, brought down our new fentanyl czar to meet with executives and folks in the White House, for example.

So I think what we've been able to show this week is enormous progress on that border.

And it's important for us to remember that a border is a two way street.

We've made progress in terms of southern flowing problems, and we're making progress with the United States on northern flowing problems.

JOHN YANG: What's been the response to that?

What do they say to that?

DAVID MCGUINTY: I think we're all encouraged because we're all remembering just the extent to which we're connected here.

We have had a relationship that goes back 150 plus years, a very productive one, frankly, a special relationship between both our countries, not something that neither of us, I think, want to compromise.

So I think what we're hearing back is thank you for bringing us up to speed.

Thank you for showing us these practical measures.

And there have been all kinds of those as I mentioned appointing a fentanyl czar, listing criminal cartels as terrorist organizations last week, a whole series of these measures which are really starting to kick in.

JOHN YANG: But in terms of meeting what the President says he wants, he says he either wants the fentanyl traffic either ended or seriously limited.

Have they told you what seriously limited means?

DAVID MCGUINTY: We know what seriously limited means.

It means as little as possible if no fentanyl, because fentanyl is a terrible scourge wreaking havoc in both of our countries.

There are some days on a per capita basis, there are more Canadians dying from fentanyl and opiate overdoses than the United States.

So we understand this, we get this.

We also know that we cannot wrestle the fentanyl crisis to the ground unless we do it together.

JOHN YANG: Looking at the statistics, there's very little compared to the southern border.

Very little comes in over the northern border.

DAVID MCGUINTY: Less than 1 percent of fentanyl entering United States comes from Canada.

Less than 1 percent of illegal immigration in the United States comes from Canada.

But there's more to be done.

And I think this week was a very good series of meetings for us to share the improvements and to see where we can continue to cooperate.

JOHN YANG: As you say, the Canadian fentanyl czar, Kevin Brousseau, was on your delegation.

His appointment is one of the things that helped President Trump decide to delay these tariffs at the beginning of February.

How was he received?

What was he able to tell them about what he's done since he's been in that job and how was it received?

DAVID MCGUINTY: I think it was very well received in the sense that the administration and politicians and others understand that this fentanyl crisis is a whole of society problem.

It's not just law enforcement.

It's not just chemistry and tracking and tracing precursors, for example, from other parts of the world.

It's many factors, many players together.

And Kevin Brosseau's job, the fentanyl czar's job in Canada is to help integrate all of those responses so we can really wrestle us to the ground.

You know, just last week we convened six of Canada top banks to strike a new agreement on tracking and tracing money flows, finding out how folks are money laundering through our banks, engaging the private sector.

When we listed these cartels as terrorist organizations, we've given our law enforcement now more powers to interrupt the flow of money and really to go after the money and to seize assets, even assets of those who cooperate with these groups.

JOHN YANG: Well, you talk about the fentanyl problem, that it's got to be worked on both sides.

Is this a bit like the drug situation a few years ago, that it's not so much the supply as it is the demand?

DAVID MCGUINTY: It's both.

It's both.

And it's wreaking havoc on our communities right across both of our countries, which is why we're here to indicate the degree to which we're prepared and are cooperating.

Another measure we just launched together is a new joint strike force.

10 new teams in the United States and Canada working together, more cooperation at the border, more cooperation in terms of tracking and technology.

So these things we believe will really help wrestle the scourge to the ground.

JOHN YANG: Based on your meetings this week, is there any reason to hope or believe that these tariffs will be paused again, as they were at the beginning of February?

DAVID MCGUINTY: You know, one of the things I've learned a little while ago is we can only control what we can control.

But the president of the United States and the new administration has said they had concerns about these issues.

We've addressed them to the best of our ability.

JOHN YANG: Canadian Public Safety Minister David Mcguinty, thank you very much.

DAVID MCGUINTY: Thank you very much.

JOHN YANG: A new study shows that Americans risk of developing dementia at any time after turning 55 is more than double what earlier research found.

The New York University study estimates that the number of dementia cases will double by 2060, reaching 1 million new diagnoses each year.

Dr. Joseph Coresh is the director of the Optimal Aging Institute at NYU's Langone Health System.

He's also one of the authors of the study.

Dr. Koresh, how significant is the findings?

DR. JOSEPH CORESH, NYU's Langone Health System: I think it's important for all of us, right.

Because if you're thinking about your lifelong health, it makes you realize that you need to consider the risk that at some point you may hit dementia before death.

JOHN YANG: And what accounts for the higher risk?

JOSEPH CORESH: So basically, we did a study that was more diverse in more centers and spanned both white and black Americans.

And we also spent an enormous amount of energy to make sure we captured all of the cases.

And then the population has gotten older.

So as life expectancy has gotten older, the risk is higher.

So the risk by age 75 is 4 percent.

By age 85, it's 20 percent And by age 95, it rises to the full 42 percent chance of getting to dementia before death.

But more than half the risk is after age 85.

JOHN YANG: So I just want to make sure I understand this is because the population is aging.

It's not that something has changed about dementia.

JOSEPH CORESH: Exactly.

The population in the U.S. is aging.

And that is also the reason that we expect the number of new dementia cases to double between now and 2060.

It's also true that our estimate of the incidence, the risk, is higher than the previous estimate.

But I think our estimate aligns with the current estimate of the number of people we have in dementia in the U.S. which is about 6 million people.

And the old estimate of risk needed to be adjusted, it was about twofold too low.

JOHN YANG: Who's most at risk for developing dementia?

JOSEPH CORESH: So when you get to 42 percent, you're really talking about all of us.

When you talk about earlier onset, Black Americans are at higher risk.

People who are genetically susceptible with a gene called APOE e4 alleles are at higher risk.

So that risk manifests before the age of 75.

And then women, because they have a lower risk of mortality, get to the more advanced ages.

And as we said, more than half the risk is after age 85.

And women are more likely to get there, so they have a higher lifetime risk.

JOHN YANG: Why is the higher risk among black Americans?

JOSEPH CORESH: So among black Americans, I think we'll get to the fact that the Lancet Commission estimates that about half the risk of dementia is preventable.

The factors include more education and better quality education at early life and creating cognitive reserve.

And the black participants, particularly the ones in this study, which were often from Jackson, Mississippi, probably had fewer educational opportunities.

The other thing that's happened is vascular risk factors are connected to dementia risk.

And so the black participants had more hypertension, more diabetes, more obesity, and possibly somewhat less treatment for those conditions, increasing their risk.

JOHN YANG: Is the health care system ready for this surge in dementia cases?

JOSEPH CORESH: I think we're already struggling with the number of dementia cases we have.

I think we need to think about how to adjust to our aging population, which would include both trying to reduce the risk of dementia through some of the risk factors I talked about.

And then we need to make sure older adults are allowed and able to stay productive and are not socially isolated, which is another risk factor for dementia.

And then at the oldest ages, we will need more ability to have care and partnerships between care facilities, care team, healthcare teams and families.

So there is a lot of work to do.

JOHN YANG: It's very interesting.

What is the link between hearing and developing dementia?

JOSEPH CORESH: So we've spent quite a bit of time on that.

It is clear that people who have hearing loss and hearing loss increases dramatically with age, much like dementia, are at an increased risk of dementia.

And last year we published a large randomized study which showed that in the first three years, if you're at high risk of having cognitive decline, hearing aids with a proper fitting and several times to make sure you really use them, the majority of the people found them to be transformative, improving their quality of life and reduce their rate of cognitive decline by 48 percent.

JOHN YANG: What are some of the other mysteries of dementia that researchers are still trying to unlock and answer?

JOSEPH CORESH: I think the biggest thing for us is the focus on late onset dementia after age 85.

Because we have more than half the cases of dementia, the number of years with dementia is lower.

But it's really important both societally and in terms of quality of life and engagement.

I do think that we should spend a little time on the good news that over the last 10 to 20 years we've realized that a lot of dementia risk is preventable.

JOHN YANG: Talk about what can be done to prevent it.

JOSEPH CORESH: Yeah.

So the Lancet Commission has a wonderful report that names 14 different risk factors.

I'm not sure I'll hit them all, but early in life we talked about more education to create cognitive reserve.

You want to avoid traumatic brain injury, both early, middle and late life sports injuries and later in life falls.

Once you hit your head hard enough, you need to allow your brain to recover or otherwise you have an increased risk of dementia.

In midlife and later, vascular risk factors prevent diabetes, no smoking, less alcohol, blood pressure control and low blood pressure is critical.

Cholesterol and obesity, as you get later in life, sensory losses, hearing and vision, correcting those should really help.

And as you get to very late in life and even earlier, social isolation, depression, addressing those issues and then later teamwork in terms of caring for people can allow lots of people, even with the onset of dementia, the majority of people in early stages stay at home, can be cared for by family members and with the correct teamwork and medication, be managed quite well.

JOHN YANG: Very interesting.

Dr. Joseph Coresh, thank you very much.

JOSEPH CORESH: My pleasure.

Thank you for having me.

JOHN YANG: And that is PBS News Weekend for this Saturday.

I'm John Yang.

For all of my colleagues, thanks for joining us.

See you tomorrow.

(BREAK) END