Middle age 'starts at 70' claims media

“Middle age begins at 70, say researchers,” The Times reports. A new population modelling study estimates that due to increased lifespan, what was once regarded as elderly should be seen as middle-aged, and this trend will continue into the future.

Traditionally, medical professionals, particularly epidemiologists, regarded 65 as the age at which somebody becomes elderly. This was based on the expectation that they probably only had a few years left to live.

As this study argues, however, this expectation is no longer valid.

Improvements in life expectancy and health mean that categorising someone as old because they've turned 75 no longer makes sense.

Instead, they suggest looking at how long a person may have left to live, based on average life expectancy, which in the UK is currently around 89 years for men and 92 for women (this is expected to rise in the future).

This means that people in their late 70s with a life expectancy of 10 to 15 years would not count as old, and the proportion of the population considered old would be smaller.

While healthy living may contribute to longer lifespans, the study doesn't suggest that we hit middle age later. Using the new definitions, middle age lasts longer, with old age postponed to our last decade-and-a-half of life.

## Where did the story come from?

The study was carried out by researchers from Stony Brook University in the US and the International Institute for Applied Systems Analysis in Austria. It was funded by the European Research Council.

The study was published in the peer-reviewed medical journal PLOS One, which is an open-access journal, meaning that it can be read for free online.

The media focused on the comments made by the researchers to explain why they had done the study, rather than the content of the research paper itself, with much discussion of how people now stay healthier for longer. The Times' headline said that middle age now starts at 60, which is not claimed anywhere in the study. The Daily Telegraph seems to think that living longer stops you ageing – "baby boomers refuse to grow old" – sadly, this is not the case.

The Mail Online did a better job of explaining the arguments behind the research, although they said that "the proportion of old people actually falls over time" using the new analysis. However, this was not borne out by the figures.

## What kind of research was this?

This was an analysis of population data using the cohort component method. It involved making different calculations of possible future scenarios, from information about the age and sex of European populations. The researchers used assumptions about future birth rates, death and migration, and how they could change over time. The results and conclusions all relate to what happens to ageing at population level, so can't be used to predict what might happen to individuals.

## What did the research involve?

Researchers took international population data and calculated what would happen to the proportion of people in a country considered old, and to the median (average) age of the population. They first used conventional measures, then their own new measures. The new measures are designed to take into account the fact that older people now, and in the future, are likely to be healthier, with a longer life expectancy, and are less dependent on others than they used to be. The researchers wanted to see what effect these new measures would have on how we think about the age of a population.

Researchers based their calculations on information from the European Demographic Data Sheet 2014, which includes statistics about the populations of European countries. Conventional measures of old age and median age are based on chronological age in years, with 65 often taken as the point at which someone is classed as old. Because life expectancy is rising, by this measure, the proportion of the population classed as old will go up over time, and will rise faster as life expectancy improves.

However, people aged 65 and over may be fit, independent and working, so this measure may not be useful for governments wanting to plan future pension provision or health and care costs.

The researchers call their new measure "prospective age". They say that people should only be considered old when their remaining life expectancy falls below 15 years, because it is in the last remaining years of life that people are most likely to be dependent and to have health problems.

Life expectancy varies for different countries, because it is calculated based on the average age of death for men and women in that country. It usually rises over time, as medicine and healthcare improves.

They also looked at median age, which is the average age of the population. As people live longer, the median age increases. However, the researchers argue, this does not take into account changing life expectancy. Instead, they calculate prospective median age, which is a measure of how long people have left to live, not just how long they have already lived.

Prospective median age is the age where remaining life expectancy is the same as the median age in a specific year. Again, this changes over time.

The researchers compared the conventional measures and the prospective measures of the percentage of the German population considered old in 2013, 2030 and 2050, under three scenarios:

* one in which life expectancy did not increase
* one in which it increased by 0.7 years per decade
* one in which it increased by 1.4 years per decade

The European Demographic Data Sheet assumes a 1.4 years per decade increase. The researchers also calculated the median age and the prospective median age of the German population under those three scenarios.

## What were the basic results?

The proportion of people considered old in the future would be smaller, based on the researchers' prospective age measures, compared to current measures based on chronological age.

Using standard measures, the proportion of the German population considered old would rise from 20.7% in 2013 to 27.8 in 2050 with no increase in life expectancy, or to 33% with the predicted life expectancy increase. However, using the prospective old age (when people had a life expectancy of 15 years or less), the proportion considered old would be 14.8% in 2013, 20.5% in 2050 with no increase in life expectancy, or 19.7% with the predicted life expectancy increase.

Conventional median age of the German population would rise from 46.5 years in 2013 to 49.3 with no increased life expectancy, or 52.6 with predicted life expectancy improvements. Using prospective median age, taking into account time left to live, it would actually fall to 45.6 by 2050 with predicted improvements in life expectancy.

## How did the researchers interpret the results?

The researchers say their results demonstrate that conventional measures of population ageing are "incomplete" because they do not take into account rises in life expectancy and what this means for people's lifestyles. In their measures, the old age threshold changes over time as life expectancy changes.

They say their prospective measures show that "faster increases in life expectancy lead to lower population ageing". In other words, although people live longer, they don't hit the threshold of being considered old as soon – so the population as a whole is middle-aged for longer.

They admit that some of the thresholds chosen for their study are arbitrary. For example, they could have used 60 for the conventional old age threshold, or used a prospective old age threshold of 10 remaining years of life. They say that the "major trends" would have been the same if they had done that, although they do not show this data.

## Conclusion

This study is an interesting analysis of population data, which shows how looking at figures from a different perspective can change our view. We are used to hearing about "ageing Britain" and how the increasing numbers of older people could be a drain on the country's resources. This study considers whether our definitions of old age are too rigid and need to be revisited.

In the paper, the researchers focus on results for Germany, but they have done calculations for 40 European countries, including the UK. This shows that the proportion of people in the UK aged 75 or over, given expected improvements in life expectancy, would rise from 17.2% in 2013 to 24.9% in 2050. However, the proportion in the last 15 years of their life would rise from 10.9% in 2013 to 13.7%. That still represents a large and increased proportion of the population considered old.

While it’s true that, on average, people are living longer, healthier lives than in the past, the study can only make predictions based on assumptions that may or may not turn out to be correct. The paper did not go into those assumptions, so we don't know whether, for example, they factored in the possible impact of being unable to treat infections because of rising antibiotic resistance, or the increased numbers of people with diabetes due to obesity.

Studies like these make for interesting headlines and give governments a new way of thinking about how to plan for our ageing population. However, they are no predictor of what will happen to any of us on an individual basis as we get older.

While there is no guarantee of your future lifespan, you can try to live longer by reducing your risks of getting some of the most common causes of premature death: