title: Propositional density and apolipoprotein E genotype among persons at risk for familial Alzheimer's disease.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: SDSU/UCSD Joint Doctoral Program in Clinical Psychology, San Diego, Calif., USA. MedinaL @ rohan.sdsu.edu
authors: Luis D
authors: LD
authors: Medina
authors: Yaneth
authors: Y
authors: Rodriguez-Agudelo
authors: Daniel H
authors: DH
authors: Geschwind
authors: Paul E
authors: PE
authors: Gilbert
authors: Li-Jung
authors: LJ
authors: Liang
authors: Jeffrey L
authors: JL
authors: Cummings
authors: John M
authors: JM
authors: Ringman
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology; D000544:Alzheimer Disease / Q000235:genetics*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics; D001057:Apolipoproteins E / Q000235:genetics*; D004522:Educational Status; D005260:Female; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D007802:Language; D008297:Male; D017058:Mexican Americans; D008800:Mexico; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D053764:Presenilin-1 / Q000235:genetics; D053766:Presenilin-2 / Q000235:genetics; D011569:Psychiatric Status Rating Scales; D012044:Regression Analysis; D012306:Risk; D014481:United States / Q000208:ethnology
chemical_list: D016564:Amyloid beta-Protein Precursor; D001057:Apolipoproteins E; C508853:PSEN1 protein, human; C508861:PSEN2 protein, human; D053764:Presenilin-1; D053766:Presenilin-2