Low HDL Cholesterol Is a Risk Factor for Deficit and Decline in Memory in Midlife

   

Objective— The purpose of this study was to examine the relationship between fasting serum lipids and short-term verbal memory in middle-aged adults.

Discussion

This study of middle-aged adults suggests a robust association between low HDL-C and poor memory. Furthermore, decreasing HDL-C was associated with decline in memory over a 5-year follow-up. These associations remained after adjustment for the effects of education, occupational position, prevalent disease, or medication use, and they were independent of APOE e4 status. Serum concentrations of total cholesterol and triglycerides show no association with memory deficit or decline. Thus, our results identify HDL-C as being important for memory.

Many previous investigations into the association between lipids and memory in the elderly have focused on total or LDL-C,^5,33 perhaps because of their status as proven risk factors for cardiovascular disease. Our findings emphasize the need to expand the focus to HDL-C. In our study on middle aged adults, the associations of low levels of HDL-C with memory deficit and decline were independent of other lipids and robust to adjustments for a number of potential confounding factors. There are a number of plausible mechanisms connecting low levels of HDL-C and memory, as HDL-C is the prominent lipoprotein in the human brain²⁷ and is involved in the regulation of amyloid β protein metabolism and deposition in the brain.³⁴ Deficit in HDL-C could also affect memory through its influence on atherosclerotic disease and stroke,³⁵ or subclinical vascular injury not reflected in the covariates examined. Other possible mechanisms linking low levels of HDL-C to neurodegenerative processes might involve its antiinflammatory³⁶ or antioxidant³⁷ properties. 

 
http://atvb.ahajournals.org/content/28/8/1556.full

Graham