Impact of plasma lipids and time on memory performance in healthy elderly without dementia

Objective: To examine the association of plasma lipid levels to changes in cognitive function in elderly subjects without dementia. Methods: The authors examined changes in performance in tests of memory, visuospatial/cognitive, and language abilities in 1,147 elderly individuals without dementia or cognitive impairment at baseline followed for 7 years using generalized estimating equations. Results: Performance in all cognitive domains declined significantly over time, while there was no association between levels of any plasma lipid or lipid lowering treatment and memory, cognitive/visuospatial, or language performance at any interval. Higher age at baseline was related to lower scores in all three domains at each interval, while higher education and white ethnicity were associated with higher scores in all domains. Analyses relating plasma lipids to performance in color trails tests using proportional hazards regression showed no association. In subsequent analyses excluding subjects with incident dementia, memory performance declined over time, while cognitive/visuospatial and language performance did not. Higher plasma high density lipoprotein and total cholesterol were associated with higher scores in language performance at baseline; this domain declined faster among individuals with higher total cholesterol, but this result was not significant after taking multiple comparisons into account. Plasma triglycerides, low density lipoprotein, or treatment with lipid lowering agents were not associated with changes in cognitive performance. Conclusions: Plasma lipid levels or treatment with lipid lowering agents in the elderly were not associated with changes in cognitive function.