Background: Plasma free fatty acids (FFAs) are a byproduct of lipolysis largely derived from adipose tissue. High plasma FFA levels have toxic effects on a variety of organs central to cardiometabolic disease. Whether FFAs associates with cognitive decline or dementia remains unknown.
Objective: To assess the association of plasma FFAs with risk of cognitive decline and dementia.
Methods: Plasma FFAs were measured in participant samples from the 1992-1993 study visit of the Cardiovascular Health Study (CHS) (mean age 74 yrs; 59% female; 14% African American [AA]; 24% APOE4 carriers). A total of 3,242 non-demented participants were followed with adjudication for dementia through 1998-1999 (n=456 cases). In addition, cognitive decline was assessed annually among all CHS participants using the 100-point modified Mini-Mental State examination (3MSE; n=4,417) and the Digital Symbol Substitution Test (DSST; n=4,254).
Results: Higher plasma FFAs levels were positively associated with risk of dementia (Figure: Log-rank p-value=0.04). In Cox regression analysis adjusted for demographics, FFAs remained associated with risk of dementia (HR per SD [0.20 mEq/L] =1.10; 95% CI, 1.00-1.22). In fully adjusted models that included lifestyle factors, medical history, C-reactive protein, LDL-C, HDL-C, and 3MSE at baseline, the hazard ratio per SD was 1.13 (1.01-1.26), with a particularly strong association observed among AA participants (HR=1.49 [1.10-2.01], p interaction=0.08). FFA levels did not differ by APOE genotype, and adjustment for genotype did not influence results. FFA levels from the baseline visit were also associated with a decline in both cognitive assessments over 6 years of follow-up, with significant time x FFA interactions (p=0.04 for 3MSE and p=0.002 for DSST). We observed no interactions with APOE genotype or race for cognitive outcomes.
Conclusions: In non-demented older men and women, higher plasma FFA levels are associated with faster cognitive decline and higher risk of dementia over the subsequent years.