Serum apoliprotein E levels in alzheimer's disease and extreme longevity.

Aims of this study were to evaluate the influence of apolipoprotein E (apoE) genotype on serum apoE levels, and, secondly, to study serum apoE concentrations in relation to age and Alzheimer's disease (AD). ApoE genotypes, serum total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), TC/HDL-C ratio, triglycerides, and serum apoE were measured in 52 healthy centenarians, 49 AD patients, 45 age-matched controls, and 72 young healthy adults. In all study population a significant trend in reduction of serum apoE levels from apoE ε2- to ε4-carriers was observed. When we adjusted for lipoprotein variables, the difference in serum apoE levels among age groups significantly decreased only including HDL-C; no significant differences between AD patients and age-matched controls were found. In these highly selected populations, serum apoE levels appear to be strongly influenced by the apoE genotype distribution, not suggesting, at present, a possible role of apoE serum concentration as a biochemical marker for AD, but only as a putative longevity factor.