For the first time in recorded human history, the number of people over 65 outnumbers children under 5.
Driven by falling fertility rates and rapid increases in life expectancy, population ageing continues to accelerate, and the number of people aged 65 years or older worldwide is projected to grow from an estimated 857 million in 2025, to about 1.6 billion in 2050.
University of Otago researchers raised concerns about the future of New Zealand’s elderly population in a New Zealand Medical Journal article more than a decade ago.
It said population ageing presented both "opportunities and challenges".
Towards the end of life, many older people would face health problems and challenges to their independence.
Chronic non-communicable diseases imposed the greatest burden on global health and healthcare delivery, and these diseases more commonly affected older people.
There was an urgent need to understand and effectively address the increasing prevalence of age-related illnesses, which posed potentially profound economic, social and political implications for global prosperity in the decades ahead.
Due to New Zealand’s ageing population, the present approach to health and disability services provision was considered financially unsustainable.
Fundamental challenges included how to preserve the health and independence of older people, and how to prevent age-related disease and disability.
With the challenges identified, there was an opportunity to intervene.
So in 2010, researchers at the University of Otago (Christchurch), led by Prof Peter Joyce, embarked on a wide-ranging longitudinal study — the Canterbury Health and Ageing Life Course Study (Chalice) — in a bold effort to understand how health and lifestyle interacted in midlife.
More than 400 Cantabrians, then aged 50, were randomly recruited, and have been studied to bring more clarity to the complex questions surrounding ageing and health.
The participants contributed health records, social, cognitive and lifestyle data, and biological samples, and the breadth of information makes the study a valuable longitudinal resource for studying human ageing.
The long-term vision of Chalice is to create practical tools, such as blood tests, that reveal who is experiencing accelerated immune ageing or cardiovascular decline.
These would allow clinicians to step in earlier with treatments or lifestyle advice which could slow deterioration and reduce disease burden.
To date, Chalice has been examining a wide variety of complex questions — such as how genes, biology and nutrition affect ageing and age-related diseases; how social, cultural and personality factors affect wellbeing and ageing; the determinants of heart disease, stroke and dementia; and later-life depression.
Researchers have also collected data to understand the impact of diet on heart health; the role of vitamin C in metabolic and cognitive health; personality traits associated with wellbeing and mood disorders; and issues such as sleep’s effect on eating behaviours and the prevalence of certain conditions such as hoarding.
It has also been examining how older people use the health system, and this data contributes to the future planning of services for the elderly.
Chalice involves a broad team of clinicians and researchers in the fields of pathology, genetics, heart disease, psychological medicine, infectious disease and depression.
Now, 15 years later, Chalice is entering a new era, with advances in genomics and biomarker analysis.
It means the study has been revitalised to ask even deeper questions about why people age differently.
University of Otago (Christchurch) Medical School biostatistician and Chalice Study co-director Associate Prof John Pearson said armed with recently collected extensive data and genome-wide genotyping, Chalice Phase 2 was set for the next wave of ageing discoveries.
"We are at the dawn of something bigger.
"These studies are the first steps toward a much larger programme that is already gathering pace."
Cardioendocrinology senior research fellow Dr Tim Prickett has been particularly interested in monitoring changes in the heart health of Chalice participants.
Fellow researchers have been focusing on cardiovascular disease by integrating genome sequencing, DNA methylation and participant outcomes to identify early genetic and epigenetic markers of heart disease.
Meanwhile, Prof Martin Kennedy’s group has been completing genome-wide genotyping of every participant, which adds unprecedented depth to the Chalice dataset and opens powerful new avenues for discovery.
University of Otago (Christchurch) pathology and molecular medicine researchers Dr Annika Seddon and Prof Mark Hampton are now using that information to investigate immune system ageing.
Dr Seddon said as people grew older, their immune systems slowed, infections lingered, vaccines lost effectiveness and "inflammaging" happened.
"Inflammaging is the gradual buildup of chronic inflammation, which drives silent damage throughout the body.
"The result is a rising risk of age-related conditions, from heart disease to blood cancers such as myelodysplastic syndromes and acute myeloid leukaemia."
Dr Seddon said the team was analysing DNA methylation to measure biological age, tracking mitochondrial dysfunction and studying immune cell composition, with the aim of detecting the earliest signs of immune decline and identifying those at risk of blood cancers.
"Chalice is a shared resource.
"When different teams ask different questions of the same dataset, we start to see how ageing biology connects across diseases.
"Inflammaging is a key part of that story, driving risk in both heart disease and cancer, and Chalice lets us measure it directly."
Prof Hampton said by understanding the underlying biology and monitoring changes in relevant biomarkers in the same people over time, they could help people stay healthier for longer.
"We can generate good insights by knowing what you’re like when you’re 50, and look at who stays well when they’re 60, who stays well when they’re 70, and what intervention should we have done at 50 to keep them that way.
"All of our work is around trying to predict who would have benefited from which intervention at 50, so that we could keep you well in your 60s and your 70s."
He said phase 2 would be interesting because it would analyse those who were in the retirement zone.
"It is a really interesting age for New Zealand because a lot of us think about retiring at about 65, and because of the way our superannuation works.
"So that’s a critical age for us to work out how do we keep you going at that point."
Assoc Prof Pearson said researchers from the Chalice Study, the Dunedin Multidisciplinary Health and Development Study and the Christchurch Health and Development Study all shared information with each other, which gave them all a "very nuanced look" at what was going on in the human body.
"When you put them together, and particularly with the other longitudinal studies in New Zealand and some of the Maori population studies, you get some very rich information about the life course in New Zealand and what happens to the health of New Zealanders.
"It means we can make much more nuanced predictions. That’s valuable."
