Improved Cognitive Function in the Tromsø Study in Norway From 2001 to 2016

Physical capacity and cardiovascular risk profiles seem to be improving in the population. Cognition has been improving due to a birth cohort effect, but evidence is conflicting on whether this improvement remains in the latest decades and what is causing the changes in our population older than 60 years. We aimed to investigate birth cohort differences in cognition.

The study comprised 9,514 participants from the Tromsø Study, an ongoing longitudinal cohort study. Participants were aged 60-87 years, born between 1914 and 1956. They did 4 cognitive tests in 3 waves during 2001-2016. Linear regression was applied and adjusted for age, education, blood pressure, smoking, hypercholesterolemia, stroke, heart attack, depression, diabetes, physical activity, alcohol use, BMI, and height.

Cognitive test scores were better in later-born birth cohorts for all age groups, and in both sexes, compared with earlier-born cohorts. Increased education, physical activity, alcohol intake, decreasing smoking prevalence, and increasing height were associated with one-third of this improvement across birth cohorts in women and one-half of the improvement in men.

Cognitive results were better in more recent-born birth cohorts compared with earlier born, assessed at the same age. The improvement was present in all cognitive domains, suggesting an overall improvement in cognitive performance. The 80-year-olds assessed in 2015-2016 performed like 60-year-olds assessed in 2001. The improved scores were associated with increased education level, increase in modest drinking frequency, increased physical activity, and, for men, smoking cessation and increased height.