A recent population-based study found that established risk factors for Alzheimer's disease are associated with cognitive performance in adults aged 24 to 44 years.
Researchers from Columbia University and the University of North Carolina at Chapel Hill conducted a cross-sectional analysis of data from Waves IV (2008) and V (2016–2018) of the National Longitudinal Study of Adolescent to Adult Health (Add Health). The findings were published in The Lancet Regional Health – Americas.
The analysis included up to 11,449 participants in Wave IV and between 529 and 1,121 participants in Wave V (depending on the analysis), with survey-weighted median ages of 28 years and 38 years, respectively. Cognitive assessments included immediate word recall, delayed word recall, and backward digit span. The Cardiovascular Risk Factors, Aging, and Incidence of Dementia (CAIDE) score—a composite measure based on age, education, sex, systolic blood pressure, body mass index, cholesterol, and physical activity—was significantly associated with all three cognitive outcomes in Wave IV. Among adults aged 24 to 34 years, each 1-point increase in the CAIDE score corresponded to a 0.03–standard deviation decrease in backward digit span score (95% CI: −0.04, −0.02).
In Wave V, higher total Tau concentrations were significantly associated with lower immediate word recall (β = −0.13, 95% CI: −0.23, −0.04). Neurofilament light (NfL) showed a non-significant trend toward lower backward digit span scores (β = −0.06, 95% CI: −0.16, 0.04).
Several inflammatory markers were also associated with cognitive performance. In Wave IV, interleukin-10 (IL-10) was associated with lower delayed recall scores (β = −0.05, 95% CI: −0.09, −0.01), IL-6 was associated with lower backward digit span (β = −0.04, 95% CI: −0.08, 0.00), and high-sensitivity C-reactive protein (hsCRP) was associated with lower backward digit span (β = −0.04; 95% CI, −0.08 to −0.001). In Wave V, IL-6, IL-8, and IL-1β were significantly associated with lower scores in multiple domains, with IL-8 showing associations with all three cognitive measures.
No associations were observed between apolipoprotein E ε4 (APOE ε4) carrier status and cognitive outcomes in either wave.
According to lead author Allison E. Aiello, PhD, of Columbia University's Robert N. Butler Columbia Aging Center, the study indicates that Alzheimer's disease risk profiles may be detectable before middle age, highlighting the need for early prevention in the U.S. population.
The study was funded by NIH grants, including P01HD31921, U01AG071448, U01AG071450, R01AG057800, P30AG066615, T32HD091058, and P2CHD050924.
No conflicts of interest were reported.