The 21st century began with the first draft of the human genome, and with it, the promise of immense new powers to treat, prevent and cure disease.
In high-income countries like Australia, rates of heart disease were falling, and life expectancy was rising.
Over the past two decades, lots has changed about the factors that affect our health, wellbeing and how long (and well) we live.
So what do we know now that we didn’t then, and how far have we come?
As part of Radio National’s Big 20 series, Dr Norman Swan speaks to three leaders in their field to find out what’s happened in dementia research, cancer care and chronic disease over the last 20 years.
Chronic disease has been getting worse
Dr Norman Swan talks to Professor Chris Murray, director of the Institute of Health Metrics and Evaluation at the University of Washington.
Dr Swan: Take us back to the year 2000. What was the pattern of disease?
Professor Chris Murray: In the year 2000, right before the big push globally on reducing health problems in low income settings, we were pretty much nearing the peak of the HIV epidemic and, particularly in sub-Saharan Africa, we still had a very large number of deaths under age five — 12 million or so a year.
We hadn’t yet had the big efforts to control malaria. And many middle-income countries were right in that transition from a profile of disease burden dominated by infectious diseases and starting that shift towards cancer, heart disease, chronic kidney disease.
Listen to the podcast
Hear the full interviews with Dr Norman Swan on the Health Report podcast.
In the high-income world — Australia, Europe, North America — the [disease burden] looked pretty similar. It was already heavily dominated by heart disease and cancer, chronic kidney disease, but there was less obesity back then, there was less diabetes, and we were still back in the heyday of heart disease coming down pretty rapidly.
Dr Swan: What has happened in the two decades since?
Professor Murray: We’ve seen really dramatic progress bringing down child death rates.
In a place like Niger in West Africa, the improvements are just spectacular. You’ve probably halved child death rates in that period … bringing [it] down below the 5 million mark because of antiretrovirals for HIV.
There has been real progress on controlling malaria because of bed-net programs. So just lots of progress racked up, until COVID, on a number of fronts in the low-income world.
Then at the other end of the spectrum in the high-income world, we’ve seen heart disease progress slow, and in some places reverse.
We’ve seen this steady rise of obesity and bringing with it diabetes, high blood sugar, bringing up blood pressure levels in some countries, despite all the therapies that exist for them.
In the middle-income world we’ve seen progress but we’ve seen the rise of ambient air pollution in the last two decades. It’s becoming a bigger and bigger issue in China and India and a number of other upper-low-income, middle-income settings.
Ambient air pollution is a risk factor for cancer, for chronic obstructive pulmonary disease, for a range of cardiovascular outcomes, including ischaemic heart disease and stroke.
Dr Swan: For countries like Australia, where rates of heart disease aren’t improving, is it obesity that’s the problem?
Professor Murray: Most of us believe that the main driver of the stall for heart disease is obesity. And that’s one and the same with high blood sugar and also has this knock-on effect on blood pressure.
The other possibility is that there has been [a lack of] innovations in therapy. We haven’t seen major new innovations for stroke and ischaemic heart disease and other major cardiovascular outcomes … so maybe that’s also part of it. But probably obesity is the biggest driver.
Dr Swan: What has happened to life expectancy?
Professor Murray: In a country like the US, progress was still there at the national level, but it was slower. And there were some really interesting differentials by race and ethnicity, with white middle class and poor Americans having actual reversals in some settings in life expectancies. Then in the last three or four years it stalled out on life expectancy.
We’ve seen the same [stalling of progress] in a number of countries in Europe. If you dig into it, the reductions in heart disease [rates] aren’t there anymore, we are seeing a rise in diabetes, and in some places we are also seeing the phenomenon people talk about as ‘the deaths of despair’; rising deaths from suicide and drug use.
Dementia dogged by drug failures
Dr Norman Swan talks to Henry Brodaty, scientia professor at the Centre for Healthy Brain Ageing at the University of New South Wales.
Dr Swan: There is some good news in the last 20 years — incident rates of dementia are falling in rich countries. Is it happening in Australia too?
Professor Henry Brodaty: We don’t have very good data for epidemiology [of dementia] in Australia, but it seems to be a consistent finding across Western European countries and in the United States and the UK.
I should stress that the number of new cases [are falling] but the actual number of existing cases is going up because people are ageing.
We think [the drop in dementia cases] is because of the prevention of dementia — with a number of vascular risk factors, risk of coronary disease and stroke going down — and we are looking after our blood pressure better, we are smoking less, and we are getting better education.
[But] possibly because we have this epidemic of diabetes and obesity, that may counteract some of the gains that we’ve had in the last 20 years.
Dr Swan: In the year 2000, everyone was going on about amyloid and Alzheimer’s disease. Have we been barking up the wrong tree for 20 years?
Professor Brodaty: There hasn’t been a new drug for Alzheimer’s disease for 20 years, despite billions of dollars being invested. There is a drug currently before the FDA called Aducanumab, it’s an antibody against the amyloid protein. About two weeks ago, the FDA said they’re going to hold off — they don’t want to give a decision on this yet, so it’s in limbo.
Dr Swan: If targeting amyloid isn’t the answer, what is it likely to be?
Professor Brodaty: People have looked at the tau protein as well, and trials there haven’t been successful. There are people trying stem cells, trying to introduce agents using viruses injected into the body to introduce it into the brain. But it may be we don’t have a treatment or it may be we need multi-pronged treatments.
People have looked for infections, and so far that hasn’t been successful. The bloodstream is important and we know that vascular risk factors not only increase the risk of vascular dementia but also Alzheimer’s disease, and that’s a much more achievable target working on things like blood pressure, and physical activity, exercise.
Failure of Alzheimer’s drug trial ‘devastating’, as researchers grapple with where to go next
Some scientists say ‘we’re on the right path’. Others insist it’s time to ‘go back to square one’. Where to next for Alzheimer’s disease?
Dr Swan: Let’s look at prevention — is there evidence that brain training works, and if so what kind?
Professor Brodaty: It works modestly — better in healthy, older people trying to stop cognitive decline and in people with mild cognitive impairment, than in people who already have dementia.
Certainly, for prevention there is evidence for [exercise], and people who are physically inactive are more likely to develop dementia.
Dr Swan: What about psychosocial interventions?
Professor Brodaty: We know that one of the big complications of dementia are the behavioural issues. And we know the drugs don’t work — people have been using antipsychotics and have a high rate of serious side effects, including stroke and death, and so there has been a big push to reduce use of medications.
Psychosocial interventions, such as stimulating people using music, humour therapy, person-centred care (there are many kinds) have all been shown to reduce the behaviours without side effects.
We are now getting to the stage where we prescribe the psychosocial intervention with the same precision that we use for pharmacogenomics for breast cancer.
Want more science — plus health, environment, tech and more? Subscribe to our channel.
Cancer survival rates have improved, but not for all
Dr Norman Swan talks to Fran Boyle, professor of medical oncology at the University of Sydney.
Dr Swan: The 21st century began with a first draft of the human genome, which promised all kinds of benefits for people with cancer. Has the Human Genome Project paid out for cancer?
Professor Boyle: Some of the biggest benefits — for instance [identifying] a type of breast cancer and the best way to treat that — probably actually predated the genome project.
But for many of the more difficult-to-treat cancers, the genome project has really sped [their treatment] up. So if you take breast cancer or childhood cancer as the frontrunners, what they have allowed some of those more rare and difficult cancers to do is to skip a couple of decades and catch up in terms of matching treatment to the type of cancer.
Dr Swan: In the year 2000, the criticism of cancer care was that there really hadn’t been substantial improvements in survival, despite an enormous amount of money being spent. How are survival rates going overall? Is it justifying the expense and the amount of research?
Professor Boyle: It is, and survival rates are improving. Even for some of the difficult cancers like pancreatic cancer, survival is improving.
But particularly for breast cancer, things have improved dramatically over that time period, and that has come about because of targeted therapies, but also because those therapies are easier to tolerate.
A real theme of cancer treatment in the last 20 years has been tolerability. How can we reduce side effects, how can we keep people on treatment longer? Because then if they are tolerating the treatment, their adherence is likely to be better. So that supportive care element is, in a way, just as important as the targeted therapies or the genomics.
It means that people you might otherwise not have been able to treat — older people, people with other comorbidities — suddenly, they become within the realms of treatable patients when they weren’t before.
Dr Swan: How have patient expectations changed over the last 20 years?
Professor Boyle: Expectations have changed — and thank goodness they have — in terms of the expectation of communication from the doctor and the other staff involved in care.
Over that time [the last twenty years] we’ve seen the growth of the multidisciplinary team approach now formalised across most cancers.
And I think the patient engagement in decisions about their care has changed for many patients and that’s a very welcome sign.
Dr Swan: But there are still unacceptable variations in outcomes. You could improve the outcome for pancreatic cancer, rectal cancer, oesophageal cancer overnight without another dollar spent on medical research — by just getting people into the best centres.
Professor Boyle: It’s partly that linkage between not only is the person a good surgeon, but do they know also when not to operate? When is that patient going to go better with chemo and radiotherapy, rather than an operation first? And that is a team decision.
One of the silver linings of this year is telehealth, and a lot of barriers could be broken down by including patients from distant or rural sites in a multidisciplinary team meeting where spectacular surgeon A, B or C operated, but is supported by a spectacular medical oncologist, radiation oncologist and clinical trials program. I think we are hoping that’s going to be one of the outcomes from this year that will make a difference.
These interviews have been edited for brevity and clarity. The full interviews are available on the Health Report podcast.