Demographic and biosocial determinants of beneficial trends in older adult cognition in the USA and England: the role of cohort succession.

Improvements in cognitive functioning in older US and English adults between 2004 and 2018 were largely driven by cohort succession increasing average educational attainment.

• Data came from the USA-based Health and Retirement Study (n = 17,305 person-years) and the English Longitudinal Study of Aging (n = 7,557 person-years)
• The study period spanned 2004 to 2018
• This pattern held for both men and women in both countries
• The Kitagawa-Oaxaca-Blinder two-fold decomposition was used to estimate contributions of population composition changes to cognitive functioning trends

Increases in the proportion of the youngest old adults counteracted the negative contributions of increased proportions of the oldest adults to cognitive functioning trends.

• Age distribution was one of three compositional areas examined alongside socioeconomic factors and chronic disease prevalence
• The finding applied to both the US and English populations
• This result reflects the within-older-adult age structure shifts occurring due to cohort succession

Increases in the prevalence of psychological conditions were detrimental to continued gains in cognitive functioning in both countries.

• Psychological conditions had negative contributions for US men, US women, and English women
• This represents a specific risk factor emerging from changing population composition
• The finding was identified through the decomposition of the composition effect component

Increases in the prevalence of diabetes and divorce were identified as specific risk factors detrimental to cognitive functioning gains for US women.

• Both diabetes prevalence and divorce prevalence increased in the US female population over the study period
• These factors negatively contributed to cognitive functioning trends specifically among US women
• Divorce was included as a biosocial determinant alongside chronic disease factors in the decomposition

Population aging does not necessarily portend an increasing burden of cognitive diseases when successive cohorts bring different socioeconomic and health protective and risk factors into older adulthood.

• The study quantified the role of cohort succession as a key demographic process influencing population cognitive health
• The analysis covered three compositional domains: age distribution, socioeconomic factors, and chronic disease prevalence
• The authors note that concerns about rapid population aging in the USA and England often neglect the demographic process of cohort succession