Health has improved among over-90s

News that people in their 90s may have better health and quality of life than ever before has been covered by BBC News, who report that "Over-90s [are] 'defying mental decline'." The news is based on a large study that compared the mental (cognitive) and physical functioning of two groups of elderly people. The groups included Danish men and women in their 90s born 10 years apart (in 1905 and 1915).

Researchers found that men and women born in 1915 performed better than those born in 1905 in terms of cognitive ability and activities of daily living, such as walking speed. These improvements remained the same when people's level of education was adjusted for.

Overall, this is a good quality piece of research. A strength was the large number of people included in both groups. But a significant limitation is that the study only involved Danish people born between 1905 and 1915. The population is also unlikely to have been ethnically diverse, so the findings may not apply to other populations.

The researchers speculate that the changes between the two groups may be because of a combination of improvements in medical practice, diet, activity levels and an increase in cognitive stimulation. This speculation is not proven by this study, however.

Regardless, it is recommended that people stay both physically and mentally active in their retirement as well as continue to eat a healthy diet. Read more about health and fitness and healthy eating.

Where did the story come from?

The study was carried out by researchers from the University of Southern Denmark. It was funded by the Danish National Research Foundation, the US National Institutes of Health (National Institute on Aging), the Danish Agency for Science, Technology and Innovation, and the VELUX Foundation.

It was published in the peer-reviewed medical journal, The Lancet.

The story was covered appropriately by BBC News.

What kind of research was this?

This was a comparative study. A comparative study directly compares one group or population with at least one other group or population in preset outcomes. In this case, the study compared two surveys of people in their 90s that took place 12 years apart, comparing people born in 1905 when they reached age 93 years with those born in 1915 when they reached 95 years.

The researchers wanted to test the functioning of elderly people in their 90s to see if they become more frail or live with more disability. The care of very elderly people is an increasingly important healthcare issue, as there is a rapidly increasing number of people living into their 90s in high-income countries.

What did the research involve?

The researchers used two groups of people in their comparative study:

people in the first group (n=2,262) were all born in 1905 and had assessments performed at 92-93 (average age 93) – these assessments took place in 1998
people in the second group (n=1,584) were all born in 1915 and had the same assessments performed at 94-95 (average age 95) – these assessments took place in 2010 (12 years later than the first group)

The authors report that no exclusion criteria were used, meaning that all people born in Denmark and living in Denmark during the relevant study periods were approached to be included, regardless of their health, cognitive status or where they were living.

The assessments performed were the same for both groups and were carried out by an interviewer from the Danish National Research Foundation. Assessment. They consisted of:

a face-to-face interview – if the participant was unable to take part in the face-to-face interview because of mental or physical handicap, a different person was encouraged to respond on behalf of the participant (by proxy)
cognitive (mental) functioning tests – assessed using a mini-mental state examination (a widely used cognitive functioning screening tool for dementia and Alzheimer's disease) and five cognitive tests sensitive to age-related changes
physical functioning tests – assessed using an activities of daily living score and physical performance tests, including grip strength, standing from a chair and walking (gait) speed
collection of biological material – for example, blood spot or a cheek swab
assessment of any symptoms of depression

The authors report the rate of response from both groups was almost identical (63% response rate in both groups).

The researchers compared the assessment results of both groups using appropriate statistical methods and performed separate analysis for men and women.

What were the basic results?

The results of the study were:

the chance of reaching 93 years of age was 28% higher in the group born in 1915 compared with the group born in 1905
the chance of reaching 95 years of age was 32% higher in the group born in 1915 compared with the group born in 1905
scores on the mini-mental state examination (the test of cognitive functioning) was significantly higher in the group born in 1915 (score of 22.8, standard deviation [SD] 5.6) compared with the group born in 1905 (score of 21.4, SD 6.0)
a significantly higher proportion of people obtained maximum scores on the mini-mental state examination in the group born in 1915 compared with the group born in 1905 (in the 1915 group, 23% had a maximum score of 28-30 points compared with 13% in the 1905 group) – this result remained significant after adjustment for level of education
cognitive composite score (the combined results for the five cognitive tests) was significantly better in the group born in 1915 (score of 0.49, SD 2.6) compared with those born in 1905 (score of 0.01, SD 3.6)
in both groups, men had better scores than women on mini-mental state examination and cognitive testing
scores on the activities of daily living scale were significantly better in the group born in 1915 compared with the group born in 1905 – men scored significantly better than women
there were mixed results for physical functioning between the 1915 and 1905 groups – there was no difference in grip strength between groups or sexes, and the group born in 1915 had a faster walking speed compared with the 1905 group, and no between-group significance testing was reported for the assessment of standing from a chair
there was no difference in depression symptom scores between groups or between males and females

How did the researchers interpret the results?

The researchers conclude that despite being two years older at assessment, the 1915 group scored significantly better than the 1905 group on both the cognitive tests and the activities of daily living score. This suggests that more people are living to older ages with better overall functioning.

The researchers go on to add that if this development continues, the future functional problems and care needs of very elderly people might be less than are anticipated based on the current burden of disability.

The authors say the finding suggests that the reason for improved activities of daily living in the group born in 1915 is improved functioning and living conditions in elderly people, as well as better aids to support mobility and independence (for example, walking aids, grab bars, ramps and swivel seats). However, this suggestion is the researchers' interpretation of the findings rather than a statement of fact, as these were not recorded in the study.

Conclusion

This was a good quality study and, although it had some limitations that the authors mention, there were positive aspects to some of the methods used:

This was a large, national study with no exclusion criteria, meaning it included people born in Denmark and living in Denmark.
Regardless of health and living status, the same study design and survey was used for both surveys.
Similar response rates for the two groups (63% response for each group).
The authors report the physical and cognitive functioning outcomes used have been shown to be reliable and valid.

There were, however, some limitations, as noted by the study authors:

As the study only included people born and living in Denmark, it would not have included any migrant populations, so findings may not be transferable to these migrant groups or to people born and living in other countries.
The people born in 1915 were assessed when they were two years older (average age 95 years) than the group born in 1905 (average age 93 years). The researchers note that functioning was relatively unchanged between groups, except for differences in the most frail and most elderly.
No subgroup analysis by disease was performed. The authors say there was no valid way of performing these analyses, and results may differ in comparisons of people with and without disease, as well as for the type and number of conditions they have, if any.

Overall, this study provides some positive evidence that people born and living in Denmark had better survival, cognitive functioning and activities of daily living if they were born in 1915 compared with people born in 1905.