OBJECTIVES: To assess the effect of lipids and lipoproteins on longitudinal cognitive performance and cognitive health in late life and to consider moderating factors such as age and sex that may clarify conflicting prior evidence.

DESIGN: Prospective cohort study.

SETTING: A 16-year longitudinal study of health and cognitive aging.

PARTICIPANTS: Eight hundred nineteen adults from the Swedish Adoption Twin Study of Aging aged 50 and older at first cognitive testing, including 21 twin pairs discordant for dementia.

MEASUREMENTS: Up to five occasions of cognitive measurements encompassing verbal, spatial, memory, and perceptual speed domains across a 16-year span; baseline serum lipids and lipoproteins including high-density lipoprotein cholesterol (HDL-C), apolipoprotein (apo)A1, apoB, total serum cholesterol, and triglycerides.

RESULTS: The effect of lipids on cognitive change was most evident before age 65. In women, higher HDL-C and lower apoB and triglycerides predicted better maintenance of cognitive abilities, particularly verbal ability and perceptual speed, than age. Lipid values were less predictive of cognitive trajectories in men and, where observed, were in the contrary direction (i.e., higher total cholesterol and apoB values predicted better perceptual speed performance though faster rates of decline). In twin pairs discordant for dementia, higher total cholesterol and apoB levels were observed in the twin who subsequently developed dementia.

CONCLUSION: High lipid levels may constitute a more important risk factor for cognitive health before age 65 than after. Findings for women are consistent with clinical recommendations, whereas for men, the findings correspond with earlier age-associated shifts in lipid profiles and the importance of lipid homeostasis to cognitive health.