Why do some people act 20 years younger than the age shown by their birth certificate, while others act 20 years older? Take Colleen Woodham for example. The mother of NewstalkZB host Kerre McIvor plays 18 holes of golf twice a week and is part of a racing syndicate, at age 82. As Paul Little explains, it turns out there is plenty of evidence that you really are only as old as you feel.
"Don't let the old man in."
This was Clint Eastwood's answer when asked why he keeps making movies and working hard in his 80s.
Maybe his string of younger girlfriends has also kept the 89-year-old young at heart? He was recently linked with Mick Jagger's ex Noor Alfallah, 23, and previously dated restaurant hostess Christina Sandera, 33 years his junior.
Closer to home, retired school teacher Colleen Woodham claims to be 82, although, listening to her weekly routine you could be forgiven for having doubts: "I've played golf for 60 years and still play 18 holes twice a week and compete," she says.
Retired school teacher Colleen Woodham claims to be 82, although, listening to her weekly routine you could be forgiven for having doubts: "I've played golf for 60 years and still play 18 holes twice a week and compete," she says.
"Then I have bridge, which I really enjoy. That's good for your thinking and means mixing with a different group of people. And I have my racing syndicate - that's another group. You have to be super optimistic to be in it. I'm not driving around in a Mercedes because of what I've won, but the joy of it is priceless. Then I have the family interests with children, grandchildren and great grandchildren."
Why do some people – like Woodham - act 20 years younger than the age shown by their birth certificate, while others act 20 years older? It turns out that there is plenty of evidence that you really are only as old as you feel.
Research shows the difference comes down to your subjective age: not how old you are in years, or how old you would like to be but how old you feel. And there's a lot of it about. After the age of 40, most people feel around 20 per cent younger than their age.
Researchers have been studying the phenomenon of subjective age and its effects for several decades, although it's gone relatively unnoticed outside medical academia.
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They have learnt it can be shaped by several factors: how old you feel, how old you look, how old you act and how old you think. It's also possible that it's a defence mechanism to protect against the social stigmas against ageing. It's certain that it's a key factor in our wellbeing as we age.
Woodham agrees: "I still don't feel old. I don't feel any different. I don't feel like an old person until people at the supermarket call me 'dear', or 'love', which is worse."
The effect of attitude on age works both ways. People who have a lower subjective age or a more positive outlook experience positive results; people with a higher subjective age or more negative view experience negative results. It's like a self-fulfilling prophecy meeting the placebo effect.
According to a survey of research published in Frontiers in Ageing Neuroscience, subjective age affects physical health, self-rated health, life satisfaction, depressive symptoms, cognitive decline, dementia, hospitalisation and frailty. A report in the Journal of Personality adds "lower chronic conditions such as hypertension and diabetes and fewer functional limitations" to the list of positives.
People who felt older than their years showed less energy, enthusiasm, sociability, intellectual curiosity and interest in variety and new experiences.
It's not just your perception of your own age that makes a difference, but also your attitude towards ageing in general.
Individuals who had positive self-perceptions of ageing lived on average 7.5 years longer than those who had negative self-perceptions, reports The Journals of Geronotology. People with a negative view of ageing also didn't cope as well with serious health problems.
"Health is a big thing to have," agrees Woodham, mother of Newstalk ZB host Kerre McIvor.
She says she's been lucky, even though "I've had a brain tumour and hip replacements. After the tumour I had to have an MRI every year, then every two years and now I don't have to go back for five years. I may not be here in five years. I've had no ill effects from it."
This attitude would be no surprise to Professor Ngaire Kerse, who is the Joyce Cook Chair in Ageing Well in the Faculty of Medical and Health Sciences at the University of Auckland.
Kerse has been conducting a study of New Zealanders aged 80 and up since 2010 with Dr Mere Kepa and Dr Lorna Dyall. She's just applied for funding to talk to them again at age 95, suggesting she's optimistic about their prospects.
Her study asked people how positive their view of ageing was. "That variable did predict health-related quality of life and longevity over time," says Kerse. "The older you were, if you were okay with being old and had positive perceptions, then you were much more likely to live longer."
She has observed another facet of subjective age and its effects when visiting nursing homes in her capacity as a GP.
"The little old ladies and men say, 'I don't want to be in here with all these old people - look at that person there'. But they are 80 and the person they're talking about is 79. You are only as old as you think you are, and everyone else is older. We externalise rather than internalise ageing, and that's a positive thing."
As to whether people can improve their lives by adjusting their attitudes and their subjective age, Kerse is hopeful but cautious.
"I think sometimes people's attitudes can be improved. but it's a whole-of-society thing. We have an ageist society. Look at images in the media – look at what is valued. It's youth, strength, beauty, especially skinniness. Those things don't tend to go with being 85. It's difficult for older people having grown up with negative thoughts and images to turn around and be positive about it."
In fact, the media may be part of the problem. A report in the New York Times in September accused advertisers of portraying anyone ever 50 as "basically dead". It cited a range of stereotypes dominating ads. For instance, people over 50 are a third of the US workforce, but only 13 per cent of images in ads showed people that age at work. There were similar numbers for images showing old people using technology, or with co-workers. And they were over-represented in images that included medical professionals. In other words, if you believe what you see in ads, old people don't work, can't handle technology and spend all their time at the doctor's.
"We need to shift the media view that elderly is an end point," says Age Concern chief executive Stephanie Clare. "An older person is still travelling through their life. Many people's attitudes will shift if they are given the opportunity. Medication now keeps us alive and well and doing what we want to do. Chronic diseases like diabetes don't stop us being independent and working. Neither should age itself be the determining factor of what you can do."
Older people also need to have a role that makes them feel valued in order to feel good about themselves. Kerse goes by the Christmas cake principle: "I like to think: who makes your Christmas cake? It was our grandmother for years, and we loved it. She used to send us jam and my husband's mother still sends us pickles."
"Age is just a number," says Clare. "At 65 you are entitled to a pension but you are also entitled to life and choice, and if you can have a good attitude you will have a good life."
Factors to consider, she says include "how we care for people long-term; how do we add value when we have a retirement age which says you're no longer wanted, hand in your keys. We know that a quarter of over-65s continue to work. Some need to, but some want to. Then there are all the other people who are over 65, volunteering, holding together organisations like sports clubs."
Modern medicine is keeping more people alive for more years but the rest of society hasn't caught up. To hear the experts tell it, we need to invest in an infrastructure for the aged. There is a generation we might call "the new old" who don't have a place aren't being catered for. Kerse says society needs to find more for old people to do, not less.
"In China they have programmes for retired people, with cognitive challenges and physical activity, music. Communities and society have to get together and work out how to do this."
Kerse has found that in care homes where the average happiness score is moderate to high people are likelier to stay happier. Some people, she says, can enjoy the benefits of being caught in a "virtuous cycle" – because they feel happy, they are happy and that keeps them and those around happy. There is also a vicious cycle available for grumpy old men and women, who will keep each other grumpy.
Another aspect of ageing that can have a positive effect is self-rated health. Kerse's research asked people a simple question about how good they thought their health was and discovered that, "regardless of what their health is really like, people who rate themselves highly tend to be better over time, less likely to go into a home, or be hospitalised and more likely to maintain independence. Thinking we are well makes us well. We should be doing more of this positive thinking."
Woodham says "the biggest wake-up call was the brain tumour and the thought you might not recover. Nowadays, walking along the river, I stop and watch the birds building their nests. You appreciate life if you have a few upheavals. It's how you go about coping with it that counts."
Clare agrees that ageing can be a mental game. "Your internal conversation tells you that you should feel old, but you don't, and you don't see it in the mirror."
She says stereotypes apply at any age: "Someone is too old to drive, or too young to run a country. We have to disrupt the thinking that it's too late to start something. It is never too late to stop smoking, never too late to learn something. But when you have a number, that sets a target. If the speed limit is 100, you drive at 100. If it's 50 you drive at 50. Similarly, if society says you are old at 65, you are likelier to feel old at 65."
But you don't have to feel old at 65. Or at 82.
"I went to the champion of champions two years ago and had to play 36 holes in the heat," says Colleen Woodham. "I came home and packed up my clubs and thought: 'That will do. I'm 80. I'll give it up.' But I couldn't give it up. A week later I'd revived."