High cholesterol levels boost memory function

This post contains a synopsis of a study published in the American Journal of Geriatric Psychiatry 2008 September; 16(9): 781–785

Study title and authors:
Better memory functioning associated with higher total and LDL cholesterol levels in very elderly subjects without the APOE4 allele
Rebecca West, M.A.,1 Michal Schnaider Beeri, Ph.D.,1 James Schmeidler, Ph.D.,1 Christine M. Hannigan, B.S.,1 Gary Angelo, M.S.,1 Hillel T. Grossman, M.D.,1,2 Clive Rosendorff, M.D., Ph.D.,1,2 and Jeremy M. Silverman, Ph.D.1,2
1Mount Sinai School of Medicine
2James J. Peters Veterans Affairs Medical Center

This study can be accessed at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2614555/

Apolipoprotein E (APOE) is found in some types of lipoptoteins that carry cholesterol around the body. About 20-25% of the population have the genetic type APOE4 allele.

 
The study examined the association of cholesterol with cognitive functioning in 185 people aged over 85 with and without the APOE4 allele.
 
The study found:
(a)  high total cholesterol and high LDL cholesterol were associated with higher memory scores for non-carriers of the APOE4 allele.
(b) there was no significant associations between cognitive performance and cholesterol levels were found for carriers of the APOE4 allele.
 
In conclusion the study found high cholesterol levels boost memory function for about 80% of the population and has no effect on the other 20%.