“Today's adults are so unhealthy they are 15 years 'older' than their parents and grandparents at the same age,” reports The Daily Telegraph. This gloomy message is based on a study that found that despite a continuing trend of increasing life expectancy, overall, the adult population is less healthy than it used to be in the past.
Researchers drew these conclusions after comparing the prevalence of risk factors for stroke, heart disease and diabetes within different generations.
It found that more recently born generations had at a similar age a higher prevalence of obesity and high blood pressure than those born 10 years earlier. Diabetes was also more prevalent among younger men, at the same age.
The good news is that the prevalence of high cholesterol did not change – possibly thanks to the development of successful treatments, such as statins.
Researchers remain unclear why the number of deaths from heart disease is falling despite poorer health. Important factors could include a reduction in smoking, as well as improved treatments.
The message from this study is undeniable: it is never too soon to take up a healthy lifestyle, including a balanced diet and plenty of exercise.
Where did the story come from?
The study was carried out by researchers from the National Institute for Public Health and the Environment, and University Medical Center Utrecht, both in the Netherlands. It was funded by the Ministry of Health, Welfare and Sport of the Netherlands and the National Institute for Public Health and the Environment.
The study was published in the peer-reviewed European Journal of Preventive Cardiology.
It was reported fairly in the media, although both the Telegraph’s and the Daily Mail’s claim that today’s adults are ‘older’ than previous generations is not a particularly sensible, useful or accurate comparison.
There is currently no direct linear association between age and health, and people in their seventies can be as healthy as those in their thirties.
What kind of research was this?
This was a cohort study that followed more than 6,000 adults, who were between the ages of 20 and 59 years at baseline, over a period of 16 years.
It aimed to find out if there were any ‘generational shifts’ in the prevalence of ‘metabolic risk factors’ that increase the chance of developing heart disease, stroke, diabetes and some other health problems.
- being overweight or obese
- high cholesterol and/or having low levels of ‘good’ HDL cholesterol
- high blood pressure
- high blood sugar, which can increase the risk of developing diabetes
The authors point out that the health of elderly people in the future is partly determined by their exposure to such risk factors over their lifetime. But little attention has been paid to whether or not there are differences in levels of risk factors between the younger and older adult generations.
What did the research involve?
The researchers used data from a cohort study that began in 1987-1991 and followed up participants after six, 11 and 16 years.
Participants were randomly selected from civil registries of Doetinchem, a small town in the Netherlands, and were aged 20 to 59 years. After the initial visit (wave one) they were invited back in three further ‘waves’ - six, 11 and 16 years later. This resulted in:
- a total of 6,308 people in wave one
- 6,070 in wave two
- 4,898 in wave three
- 4,517 in wave four
The researchers categorised people by ‘generations’ (10-year age groups) of 20-29 year olds, 30-39 year olds, 40-49 year olds and 50-59 year olds.
At each visit trained staff measured each participant for the metabolic risk factors mentioned above (with the exception of blood sugar levels). They also completed questionnaires on medical history, use of medication and lifestyle. Body weight and height were also measured and used to calculate body mass index (BMI).
Type 2 diabetes was self reported but usually supported by professional verification. Socioeconomic status was determined by highest level of completed education.
Researchers then analysed their results to find out if one generation had a different risk profile from one born 10 years earlier.
What were the basic results?
The results showed that the prevalence of overweight, obesity and high blood pressure increased with age in all generations, as to be expected. But in general, more recently born generations had, at a similar age, a higher prevalence of these risk factors than generations born 10 years earlier.
‘Unfavourable generation shifts’ were most pronounced for overweight or obesity, and were present in men between every generation. For example, 40% of men in their 30s at baseline were overweight. 11 years later (wave three), 52% of men in their 30s were overweight.
In women, these unfavourable changes in weight were only evident between the most recently born generations, in which the prevalence of obesity doubled in just 10 years.
Other findings from the study included:
- Unfavourable generation shifts in high blood pressure between every consecutive generation (except for the two most recently born generations of men).
- Unfavourable generation shifts in diabetes between three of the four generations of men, but not of women.
- No generation shifts for high cholesterol. Favourable shifts in ‘good’ HDL cholesterol were only observed between the oldest two generations.
In general, the pattern of generation shifts did not differ according to socioeconomic status, as they all worsened over time. The proportion of people in poorer socioeconomic groups with risk factors was, however, greater than the proportion with risk factors in the higher groups.
How did the researchers interpret the results?
The authors say that overall, based on increases in the prevalence of unhealthy weight and high blood pressure at younger age, "the more recently born adult generations are doing worse than their predecessors". Evidence to explain the changes is not clear, they add, but they note studies reporting an increase in physical inactivity.
In an accompanying press release, the lead author, Gerben Hulsegge, said that in terms of the findings on obesity: "The prevalence of obesity in our youngest generation of men and women at the mean age of 40 is similar to that of our oldest generation at the mean age of 55. This means that this younger generation is '15 years ahead' of the older generation and will be exposed to their obesity for a longer time."
He also argued that while reduction in smoking and improved healthcare have led to greater life expectancy, the current trends in obesity mean that "the rate of increase in life expectancy may well slow down".
This cohort study’s strength was its long follow-up period, with four measurements of risk factors taken over a period of 16 years. By following up people over time a cohort study such as this is able to track risk factors in the same people over extended periods. As long as people return for the follow-up checks, it is the best study design for tracking this sort of data and drawing the sorts of conclusions these authors make.
Another advantage is that the same group of trained workers objectively measured data on body weight, height, blood pressure and cholesterol, using standardised protocols, which reduced the chances of measurement errors.
However, it had some limitations:
- The study was based on data from people living in one town in the Netherlands and the results may not be generalisable to other populations.
- Although response rates during follow-up were good, those who dropped out before the end were more often lower educated and smokers, and were more likely to have certain risk factors, which could affect reliability of the results.
- The researchers recorded smoking at baseline (ranging from 25 to 40% among the men and women recruited) but did not report if this was measured at follow-up visits or how this has changed over the years. This appears to be an opportunity missed as it is well understood in existing research that these risk factors are often seen together.
Still, the study’s results support an important health message about establishing the need for a healthy body weight at a young age, although increased physical activity and a balanced diet should be encouraged at all ages.