A high-quality cohort study by Finnish scientists shows that today’s elderly are in better physical and cognitive shape than people of the same age were a generation ago [1,2].
Does longer also mean better?
One of the fears commonly evoked by the idea of life extension is that prolonging lifespan will not necessarily prolong healthspan. This is the concern that even if people are currently living longer, they have not become healthier, since the additional lifespan that modern medicine provides is burdened by illness and frailty. Some data, such as the rising prevalence of chronic diseases, seems to support this notion. On the other hand, there is a lot of anecdotal evidence that people today feel younger and healthier than their parents did at the same age, such as the idea that 70 is the new 60. Large-scale cohort studies could help to clear this up, but they are extremely hard to come by.
Two studies 30 years apart
A recent study by Finnish scientists is one of the most comprehensive and high-quality cohort studies ever performed. It is based on a study from 1989-1990 that was performed in the same city of Jyväskylä. Back then, 500 elderly Finns aged 75 or 80 (born in either 1910 or 1914) were tested for physical and cognitive abilities. Physical ability tests included maximal walking speed, maximal hand grip strength and knee extension strength, and respiratory function. The cognitive tests measured memory, cognition, verbal fluency, and reaction time. In this current study, the sample size has grown to 726, and the participants were born either in 1938-9 or 1942-3. In addition to both cohorts being genetically similar due to low levels of migration in this part of the country, the study’s great advantage is that the protocols were meticulously recreated three decades after the original study using the same or similar equipment.
At first glance, the results look promising, especially on the cognitive abilities front, where the later cohort convincingly outperformed the earlier one in almost every test. This is not surprising, though, as the cognitive advantage of later cohorts has been demonstrated by several studies and even has its own name: the Flynn effect [3].
There have been much fewer cohort studies of physical abilities, at times with opposing or inconclusive results. The Finnish study clearly demonstrates the advantage of the later-born cohort.
The later cohort showed markedly and meaningfully higher results in the maximal functional capacity tests, suggesting that currently 75- and 80-year old people in Finland are living to older ages with better physical functioning.
The difference between the earlier-born and the later-born cohorts was more pronounced among 75-year-old males and 80-year-old females. For instance, in the earlier cohort of 75-year-old men 48% percent showed grip strength lower than the threshold for increased risk of limited mobility, compared with only 27% in the later cohort. The results of the same test in women’s 80-year-old cohorts were 75% and 44%, accordingly.
However, these results come with many caveats, beginning with the rate of participation. In the first study, 77% of those contacted agreed to participate, while in the second, the response rate was just 44%. This caused the researchers to suspect that the second cohort was more prone to self-selection bias, and an effort was made to control for this effect.
Education, smoking and two world wars
The researchers note that numerous other factors could have affected the results. For instance, the increase in average strength can be partially explained by the increase in average height, which is a well-known worldwide phenomenon.
Apart from average height, the difference that stood out the most was in years of education, where the younger cohort had definitive advantage. Education correlates strongly with health, probably because more educated people tend to lead healthier lives, work less physically demanding jobs, and have access to better healthcare.
Another obvious factor was smoking. In the later cohort, fewer men indicated that they had ever smoked, which may have contributed to their superior health. Interestingly, the opposite was true for 75-year-old women. A possible cause is that people usually take up smoking when they are young, and in the 1930s, women who smoked were more frowned upon than 30 years later.
The researchers then delved even deeper into possible socioeconomic factors. They noted that people from the earlier cohort experienced two world wars and several periods of scarcity. The difference in average height can be explained by malnutrition and being engaged in child labor, which was widespread in Finland at that time. The 1940s marked the beginning of Finland as a welfare state, with measures like free school meals being introduced. On the other hand, environmental pollution, which also affects health and longevity, has increased over the last century around Jyväskylä due to urbanization.
Still, the results, even when controlled for variables like height and education level, were so statistically significant that the researchers view them as evidence that today’s elderly (at least in Finland) are healthier, stronger, more active and more cognitively sound than their parents were at the same age.
Conclusion
Quality cohort studies like this one, though still rare, will be increasingly available in the future. If sufficiently standardized and controlled for variables, they can help elucidate the true effects of modern lifestyles and advances in medicine on the public’s healthspan.
Literature
[1] Koivunen, K., Sillanpää, E., Munukka, M., Portegijs, E., & Rantanen, T. (2020). Cohort differences in maximal physical performance: a comparison of 75-and 80-year-old men and women born 28 years apart. The Journals of Gerontology: Series A.
[2] Munukka, M., Koivunen, K., von Bonsdorff, M. B., Sipilä, S., Portegijs, E., Ruoppila, I., & Rantanen, T. (2020). Birth cohort differences in cognitive performance in 75-and 80-year-olds: a comparison of two cohorts over 28 years. Aging Clinical and Experimental Research, 1-9.
[3] Flynn JR (1987) Massive IQ gains in 14 nations: what IQ tests really measure. Psychol Bull 101:171
