SDSU/UCSD Joint Doctoral Program in Clinical Psychology, San Diego, Calif., USA. MedinaL @ rohan.sdsu.edu
Dement Geriatr Cogn Disord. 2011;32(3):188-92. doi: 10.1159/000333023. Epub 2011 Aug 30.
BACKGROUND/AIMS: A relationship between decreased propositional density (p-density) in young adulthood and future risk for Alzheimer's disease (AD) has been postulated, but multiple interpretations of the nature of this relationship are possible. This study explored the relationship between familial AD (FAD) mutation status, apolipoprotein E (APOE) genotype, and p-density.
Thirty-five non-demented persons at risk for FAD mutations were recruited. Subjects wrote brief biographical essays from which p-density, the ratio of the number of unique ideas to the number of words in the text, was calculated. mixed-effects regression models were used to examine the relationship of p-density and fad mutation status and apoe genotype.
FAD mutation status was not significantly associated with p-density. However, results from both models indicated that the presence of the APOE ε4 allele was significantly associated with p-density (p < 0.0001), with APOE ε4 carriers having lower p-density than non-carriers.
Our results are consistent with an influence of APOE status on p-density in young adulthood that is independent of the AD risk per se and suggest the previous finding of increased risk for the development of AD in persons with decreased p-density may be related to APOE genotype.
背景/目的：有人提出，在年轻成年时，命题密度（p-density）降低与未来阿尔茨海默病（AD）的风险之间存在关系，但对这种关系的本质有多种解释。本研究探讨了家族性 AD（FAD）突变状态、载脂蛋白 E（APOE）基因型与 p-density 之间的关系。
招募了 35 名无痴呆风险的 FAD 突变携带者。受试者撰写简短的传记文章，从中计算 p-density，即文本中独特想法数量与单词数量的比值。使用混合效应回归模型来检验 p-density 与 fad 突变状态和 apoe 基因型的关系。
FAD 突变状态与 p-density 无显著相关性。然而，两个模型的结果均表明，APOE ε4 等位基因的存在与 p-density 显著相关（p < 0.0001），APOE ε4 携带者的 p-density 低于非携带者。
我们的结果与 APOE 状态对年轻成年时 p-density 的影响一致，这种影响独立于 AD 风险本身，表明之前发现的 p-density 降低与 AD 发展风险增加可能与 APOE 基因型有关。
