Friday August 31 2012
Swimming is an ideal form of exercise for older people
Being active and living a healthy lifestyle into your 70s can make a huge difference to your life expectancy, the BBC reported today.
The story is based on a large Swedish study of people aged 75 and over, which found that those with a healthy lifestyle (such as not smoking and taking regular exercise) lived, on average, more than five years longer than those with unhealthy lifestyles.
Interestingly, the researchers found that factors not directly related to physical health, such as having an active social life and regular involvement in leisure activities, also contributed to increased longevity.
The findings also applied to the very old – those aged 85 and over – and people who were chronically ill.
This large study, which followed up participants for 18 years, suggests that even when we are old, sticking to a healthy lifestyle (especially not smoking) and keeping physically active, sociable and busy can help us live longer.
One important drawback is that researchers did not look at people’s lifestyles before the age of 75. It is possible that many people led similar lifestyles in the years before they reached 75 as they did after, so it is still unclear what difference improving your lifestyle only in your later years might make to your longevity.
The picture could be more complex than this study suggests. It may also be the case that being healthier in old age means people are more active – rather than vice versa.
Still, leading a healthy, busy life can’t be a bad thing, whatever your age.
Where did the story come from?
The study was carried out by researchers from the Karolinska Institutet, Stockholm University and Stockholm Gerontology Research Center, Sweden. It was funded by a number of Swedish institutions.
The study was published in the peer-reviewed British Medical Journal.
The study was covered fairly by the BBC, which included comments from independent experts and also pointed out that it is unclear how big a difference changes made in later years could make.
What kind of research was this?
This was a cohort study which followed 1,810 adults aged 75 or over, for 18 years, to assess lifestyle and other modifiable factors associated with living longer.
While cohort studies cannot prove direct cause and effect (causality), they can be very useful in looking at associations between lifestyle and health outcomes, especially where people are followed for a lengthy period.
The researchers point out that previous research has shown that some lifestyle factors are associated with longevity in elderly people, but that so far, results have been mixed.
What did the research involve?
The research was carried out as part of a Swedish study on ageing and dementia. The initial group of 2,368 participants included all registered inhabitants in a particular district of Stockholm who were aged 75 or over at the start of the study, in 1987. Initially there were 2,368 participants, but only 1,810 (74%) were included in the analysis. The rest had either refused to take part, moved out of the area, or died.
At the start of the study in 1987, all participants undertook a survey and took part in face-to-face interviews with trained nurses to ascertain age, sex, occupation and education. Participants were also asked about their lifestyles, including smoking habits, alcohol consumption, leisure activities and social networks. Leisure activities included mental activities such as reading, writing and studying, while physical activity encompassed swimming, walking or gymnastics. Social and other activities included travelling and theatre attendance, gardening, cooking and participating in social groups for older people.
Participants were also asked about their marital status, living arrangements, family relationships and friendships to determine the extent of their social networks. They were then grouped into three social network categories of rich, moderate, limited, or poor.
Researchers used an inpatient register system covering 1969 to 1989 to find out about any history of chronic disease among participants. They used national death statistics in 2005 to ascertain the status of participants at this point.
Researchers used validated statistical methods to analyse the association between lifestyle factors and longevity, adjusting their results for factors which might have affected the results (called confounders), such as sex, education and occupation. They also analysed the association between various combinations of lifestyle factors and longevity.
What were the results?
Most of the participants (91.8%) died during the 18 years of follow up. Half lived longer than 90 years.
Below are the main findings:
- Smoking at 75 was associated with shorter survival. Half of the participants who smoked died one year earlier than non-smokers (95% confidence interval 0.0 to 1.9). The pattern of survival in former smokers was the same as that in never smokers.
- Of all leisure activities, physical activity was most strongly associated with survival. The average age at death of participants who regularly swam, walked, or did gymnastics was 2.0 years (0.7 to 3.3 years) greater than those who did not.
- The average survival of people with a “low risk profile” (healthy lifestyle, participation in at least one leisure activity, and a rich, or moderate, social network), was 5.4 years longer than those with a high risk profile (unhealthy lifestyle, no participation in leisure activities, and a limited, or poor, social network).
- Men with a low risk profile lived on average six years longer than those with a high risk profile, while women with a low risk profile lived on average five years longer than those with a high risk profile.
- Among those aged 85 or older and people with chronic conditions, the average age at death was four years higher for those with a low risk profile, compared with those with a high risk profile.
How did the researchers interpret the results?
The researchers said that even after 75, lifestyle behaviours such as not smoking and physical activity are associated with living longer. They also found that factors that we may not necessarily associate with physical health, such as social life and taking part in leisure activities, may also be associated with longer-life.
Men who "scored highest" (low risk profile) in terms of healthy lifestyle, leisure activities and social networks were found to, on average, live six years longer than men who "scored lowest" (high-risk profile).
A similar finding of five years extra living was found in low-risk women compared to high-risk women.
This study has some strengths. It followed up on its participants over a lengthy period of time and was based on detailed data about their lifestyles. Researchers also adjusted their findings for factors which are associated with living longer, such as sex and occupation.
However, it also has limitations. The study had a high drop-out rate (23.6%), which could have affected the reliability of its results.
As the authors point out, the study did not take account of all factors that could have influenced results – in particular, the quality of people’s diet. Perhaps most importantly, it did not look at people’s lifestyles before the age of 75, so it did not take account of how far lifestyle factors before that age, especially habits that had been maintained for a lifetime, could have influenced the results.
Also, the study was limited to residents of Stockholm, a largely affluent city, with a majority population of people of Northern European descent. So the findings may not necessarily apply to other populations / ethnicities.
That said, leading a healthy, busy life is a good thing at any age.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.