Worried that living longer will mean living longer with mental and physical disabilities? Your worries may be over.
Danish researchers report some encouraging news for aging populations around the world in the journal Lancet. Comparing two groups of nonagenarians, they found that those born more recently scored higher on cognitive function tests than those born earlier, providing hope that more elderly are able to not just live longer, but do so with more of their mental faculties intact.
The researchers studied nearly 4,000 people in their 90s identified by the Danish Civil Register System — one group was born in 1905 was assessed at age 93 (in 1998) while the other cohort, born a decade later in 1915, were studied in 2010 when they reached age 95. The researchers did not exclude any participants, and included those living in the community as well as those in assisted living or in institutional care that were receiving medical treatments. Despite being two years older when they were tested, the later-born group was nearly twice as likely to attain the highest score on a basic cognitive function test than those born earlier.
The people born in 1915 were also longer lived; these participants were 32% more likely than those born just 10 years earlier to reach the age of 95. “Not only are more people living to a higher age, they are also doing so in better shape, at least in Denmark,” says lead author Kaare Christensen of the Danish Aging Research Center at the country’s Institute of Public Health.
According to the World Health Organization, the U.S. and Denmark both have an average life expectancy of 79, which for Scandinavian countries ranks slightly lower than the average of 81 or 82 for other nations in the region. Denmark lags behind, says Christensen, largely because of higher smoking rates. “We’re the misbehaving little brother,” he says.
Research suggests that longevity can follow two different paths: people might survive longer because they are healthier, and therefore they may not experience much disability as they age, or, more individuals may live longer with serious illnesses or disability but receive support from extensive medical interventions. Recent data suggests that the oldest old — centenarians in particular — may actually enjoy better health than people in their 70s or 80s, hinting that those who do survive into old age may be stronger to begin with, and less likely to experience disability. Some recent studies have also found that cognitive scores among the elderly have risen, which may reflect growing levels of physical and mental activity, both of which have been linked to better mental function — among today’s elderly populations.
The current cohort of nonagenerians may also be benefiting from an overall rise in IQ among younger groups over time. In the U.S., for example, scores have improved roughly 3 points per decade since 1930, meaning that an average person tested early in the 20th century would have what would be considered an intellectually disabled IQ today. The improvement— known as the “Flynn effect,” for the researcher who identified the trend — has been attributed to everything from better nutrition and overall health to more schooling, but is still not well understood. “There’s no magic bullet to explain all of the difference,” says Christensen, “It’s likely to be a combination of improvements in living conditions over course of life, including greater intellectual stimulation early on.”
The new study suggests those effects can last a lifetime. Having stronger mental function early in life could translate into greater cognitive reserve, or a mental cushion of abilities, later in life on which nonagenarians can rely when aging starts to affect these skills. On average, the nonagenarians born in 1915 performed better on cognitive tests than those born in 1905 and they also had higher scores for being able to perform daily activities such as walking to the store, getting out of bed, and navigating stairs that are critical for independent living.
Christensen says the results don’t mean that loss of cognitive function, or dementia doesn’t continue to be a significant issue for societies seeing a growing proportion of their citizens transition into older age. But the findings do provide hope that awareness of the benefits of exercise, social interaction and continued mental stimulation could steer more elderly away from disabling conditions in their golden years, and toward more fulfilling, independent lives.