The new findings by researchers at the University of Helsinki highlight the importance of education in preventing memory disorders and provide new information on why some people maintain good cognitive function despite their advanced age.
Earlier research has shown that cardiovascular risk factors such as high blood pressure, high cholesterol, lack of exercise, and elevated body mass index increase the risk of dementia. The newly published study investigated how risk and protective factors measured decades ago predict cognitive function in people over 90.
Schooling still matters after 90
"This is an important topic, as there has been very little research on cognitive aging in people in their nineties, even though this age group is set to grow in the future. In addition, the likelihood of memory disorders is highest in late old age, says FIMM Group Leader Eero Vuoksimaa, who led the study.
The research is based on a unique long-term twin study launched in 1975, in which participants’ health has been monitored for nearly 50 years.
The results showed a clear link between education and memory performance in 90-year-olds. Participants who had attended school for 12 years or more performed better on cognitive tests than those with fewer than seven years of education. Even those with 7–11 years of schooling outperformed the least-educated group.
"The protective effect of higher education, even at the age of 90, may be related to the brain's ability to compensate for the effects of aging, a capacity strengthened by education," says Anni Varjonen, a Doctoral Researcher at the University of Helsinki and lead author of the study.
No evidence of midlife heart risk factors affecting memory at 90
No connection was found between cardiovascular risk factors and memory function in this age group. This may reflect that people who reach the age of 90 often differ from the general population, for example in terms of lifestyle or overall health.
"It is possible that people who have lived to the age of 90 are less susceptible to the effects of dementia risk factors. However, longitudinal studies with larger datasets are needed to confirm this," Varjonen says.
Cognitive function in the study was assessed via telephone interviews with 96 participants in the NONAGINTA – Memory and Health in Nonagenarians.
According to Vuoksimaa, the study also offered valuable practical insights into conducting telephone-based memory tests with this age group.
“It was great to see how many participants from the original twin study were still willing to take part,” Vuoksimaa says.
Funding: The Research Council of Finland has funded the collection of data for the NONAGINTA study. Anni Varjonen has received funding for her doctoral thesis from the Finnish Brain Foundation and the University of Helsinki's Doctoral Program in Population Health, while Eero Vuoksimaa has received funding from the Sigrid Jusélius Foundation.
Original publication: Varjonen, A., Saari, T., Aaltonen, S., Palviainen, T., Urjansson, M., Iso-Markku, P., Kaprio, J., & Vuoksimaa, E.